From 3e3239cb690057676435e6e859fb95299e0934bd Mon Sep 17 00:00:00 2001
From: Robert Rosebury <R_E_Rosebury@hotmail.com>
Date: Fri, 11 Oct 2019 16:47:27 +0100
Subject: [PATCH] [Feature] Upgraded PHPUnit to 8.4 - Updated the unit tests to
 have return type of void - Replaced usages of assertInternalType() due to
 deprecation - Changed the minimum PHP version to 7.2

---
 .gitignore                                    |   2 +-
 .travis.yml                                   |   4 +-
 composer.json                                 |   8 +-
 tests/unit/ActionTest.php                     |  12 +-
 tests/unit/AddressTest.php                    |  34 +--
 tests/unit/ApiTest.php                        |  22 +-
 tests/unit/ConfigTest.php                     |  10 +-
 tests/unit/Dns/A/ARecordTest.php              |   4 +-
 tests/unit/Dns/A/Requests/AddRequestTest.php  |  22 +-
 .../unit/Dns/A/Requests/UpdateRequestTest.php |  16 +-
 tests/unit/Dns/Cname/CnameRecordTest.php      |   4 +-
 .../Dns/Cname/Requests/AddRequestTest.php     |  20 +-
 .../Dns/Cname/Requests/UpdateRequestTest.php  |  22 +-
 tests/unit/EmailAddressTest.php               |   4 +-
 tests/unit/ExceptionMapperTest.php            |  16 +-
 tests/unit/IPv4AddressTest.php                |   8 +-
 tests/unit/MessageTest.php                    |   2 +-
 .../BusinessEmails/BusinessEmailOrderTest.php |  10 +-
 .../Requests/AddEmailAccountRequestTest.php   |   6 +-
 .../BusinessEmailOrderRequestTest.php         |  16 +-
 .../DeleteEmailAccountRequestTest.php         |   6 +-
 .../Requests/RenewRequestTest.php             |  10 +-
 .../AddedEmailAccountResponseFactoryTest.php  |   8 +-
 .../AddedEmailAccountResponseTest.php         |  24 +--
 .../BusinessEmailOrderResponseTest.php        |   8 +-
 .../Responses/CreateResponseTest.php          |  26 +--
 .../DeletedEmailAccountResponseTest.php       |  10 +-
 .../Responses/GetResponseTest.php             | 106 +++++-----
 .../Responses/RenewalResponseTest.php         |  28 +--
 tests/unit/Orders/ContactTest.php             |  24 +--
 .../Orders/Domains/DelegationSignerTest.php   |  10 +-
 .../Domains/DomainOrderDetailTypeTest.php     |   2 +-
 tests/unit/Orders/Domains/DomainOrderTest.php |   6 +-
 .../unit/Orders/Domains/NamedServersTest.php  |  10 +-
 .../Orders/Domains/PrivacyProtectionTest.php  |  10 +-
 .../RegistrantContactVerificationTest.php     |   8 +-
 .../Orders/Domains/RegistryStatusTest.php     |  10 +-
 .../Domains/Requests/GetRequestTest.php       |   6 +-
 .../Requests/GetbyDomainRequestTest.php       |   6 +-
 .../Domains/Requests/RenewRequestTest.php     |  26 +--
 .../Domains/Responses/GetResponseTest.php     | 200 +++++++++---------
 .../PrivacyProtectionOrderResponseTest.php    |  22 +-
 .../Domains/Responses/RenewalResponseTest.php |  22 +-
 .../Orders/EmailAccounts/EmailAccountTest.php |   4 +-
 .../Requests/CreateRequestTest.php            |  18 +-
 .../Requests/DeleteRequestTest.php            |   6 +-
 .../Responses/CreateResponseTest.php          |  86 ++++----
 .../Responses/DeletedResponseTest.php         |   8 +-
 .../Settings/ImapSettingsTest.php             |   2 +-
 .../Settings/PopSettingsTest.php              |   2 +-
 .../Settings/SmtpSettingsTest.php             |   2 +-
 .../Settings/WebmailUrlSettingsTest.php       |   2 +-
 .../EmailForwarders/EmailForwarderTest.php    |   2 +-
 .../Requests/CreateRequestTest.php            |   8 +-
 .../Responses/CreateResponseTest.php          |   4 +-
 tests/unit/Orders/GdprProtectionTest.php      |   4 +-
 tests/unit/Orders/InvoiceOptionTest.php       |   2 +-
 tests/unit/Orders/LockedOrHoldStatusTest.php  |   8 +-
 tests/unit/Orders/OrderStatusTest.php         |  12 +-
 tests/unit/Orders/OrderTest.php               |   4 +-
 tests/unit/ResponseTest.php                   |   6 +-
 tests/unit/StatusTest.php                     |   2 +-
 tests/unit/TelephoneNumberTest.php            |  16 +-
 tests/unit/TimeToLiveTest.php                 |  18 +-
 64 files changed, 525 insertions(+), 521 deletions(-)

diff --git a/.gitignore b/.gitignore
index adacc5e..62ead3c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,4 @@
 /.idea
 /vendor
 composer.lock
-
+.phpunit.result.cache
\ No newline at end of file
diff --git a/.travis.yml b/.travis.yml
index b50f2d1..0dabb52 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,7 @@
 language: php
 php:
-  - 7.0
-  - 7.1
+  - 7.2
+  - 7.3
 
 install: composer install
 script: ./vendor/bin/phpunit --configuration phpunit.xml
diff --git a/composer.json b/composer.json
index d4eec6e..bf6deb5 100644
--- a/composer.json
+++ b/composer.json
@@ -18,14 +18,18 @@
         "issues": "https://github.com/Pitchero/ResellerClub/issues",
         "source": "https://github.com/Pitchero/ResellerClub"
     },
+    "config": {
+        "preferred-install": "dist",
+        "sort-packages": true
+    },
     "require": {
-        "php": ">=7.0.0",
+        "php": ">=7.2.0",
         "guzzlehttp/guzzle": "~6.0",
         "nesbot/carbon": "~1.20 || ~2.0",
         "moneyphp/money": "~3.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^6.4 || ^8.0",
+        "phpunit/phpunit": "^8.4",
         "symfony/var-dumper": "^3.3"
     },
     "autoload": {
diff --git a/tests/unit/ActionTest.php b/tests/unit/ActionTest.php
index c2c2dba..f62030c 100644
--- a/tests/unit/ActionTest.php
+++ b/tests/unit/ActionTest.php
@@ -12,7 +12,7 @@ class ActionTest extends TestCase
      */
     private $action;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -25,17 +25,17 @@ protected function setUp()
         );
     }
 
-    public function testItCanGetId()
+    public function testItCanGetId(): void
     {
         $this->assertEquals(461331388, $this->action->id());
     }
 
-    public function testItCanGetType()
+    public function testItCanGetType(): void
     {
         $this->assertEquals('Add', $this->action->type());
     }
 
-    public function testItCanGetTypeDescription()
+    public function testItCanGetTypeDescription(): void
     {
         $this->assertEquals(
             'Addition of Business Email 1 for testdomainmail.com for 1 month',
@@ -43,12 +43,12 @@ public function testItCanGetTypeDescription()
         );
     }
 
-    public function testItCanGetStatus()
+    public function testItCanGetStatus(): void
     {
         $this->assertEquals('PendingExecution', $this->action->status());
     }
 
-    public function testItCanGetStatusDescription()
+    public function testItCanGetStatusDescription(): void
     {
         $this->assertEquals('The action is pending execution', $this->action->statusDescription());
     }
diff --git a/tests/unit/AddressTest.php b/tests/unit/AddressTest.php
index b60d958..5804cb2 100644
--- a/tests/unit/AddressTest.php
+++ b/tests/unit/AddressTest.php
@@ -12,7 +12,7 @@ class AddressTest extends TestCase
      */
     private $address;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->address = new Address(
@@ -27,51 +27,51 @@ protected function setUp()
         );
     }
 
-    public function testCompany()
+    public function testCompany(): void
     {
-        $this->assertInternalType('string', $this->address->company());
+        $this->assertIsString($this->address->company());
         $this->assertEquals('Company Name', $this->address->company());
     }
 
-    public function testAddressLine1()
+    public function testAddressLine1(): void
     {
-        $this->assertInternalType('string', $this->address->addressLine1());
+        $this->assertIsString($this->address->addressLine1());
         $this->assertEquals('Address Line 1', $this->address->addressLine1());
     }
 
-    public function testAddressLine2()
+    public function testAddressLine2(): void
     {
-        $this->assertInternalType('string', $this->address->addressLine2());
+        $this->assertIsString($this->address->addressLine2());
         $this->assertEquals('Address Line 2', $this->address->addressLine2());
     }
 
-    public function testAddressLine3()
+    public function testAddressLine3(): void
     {
-        $this->assertInternalType('string', $this->address->addressLine3());
+        $this->assertIsString($this->address->addressLine3());
         $this->assertEquals('Address Line 3', $this->address->addressLine3());
     }
 
-    public function testCity()
+    public function testCity(): void
     {
-        $this->assertInternalType('string', $this->address->city());
+        $this->assertIsString($this->address->city());
         $this->assertEquals('Leeds', $this->address->city());
     }
 
-    public function testCounty()
+    public function testCounty(): void
     {
-        $this->assertInternalType('string', $this->address->county());
+        $this->assertIsString($this->address->county());
         $this->assertEquals('West Yorkshire', $this->address->county());
     }
 
-    public function testCountry()
+    public function testCountry(): void
     {
-        $this->assertInternalType('string', $this->address->country());
+        $this->assertIsString($this->address->country());
         $this->assertEquals('Gb', $this->address->country());
     }
 
-    public function testPostCode()
+    public function testPostCode(): void
     {
-        $this->assertInternalType('string', $this->address->postCode());
+        $this->assertIsString($this->address->postCode());
         $this->assertEquals('LS1 1AB', $this->address->postCode());
     }
 }
diff --git a/tests/unit/ApiTest.php b/tests/unit/ApiTest.php
index 82b90a4..aab3c8f 100644
--- a/tests/unit/ApiTest.php
+++ b/tests/unit/ApiTest.php
@@ -30,7 +30,7 @@ class ApiTest extends TestCase
      */
     private $api;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -44,17 +44,17 @@ protected function setUp()
         );
     }
 
-    public function testGet()
+    public function testGet(): void
     {
         $this->assertInstanceOf(Response::class, $this->api->get('get', ['request-param' => 123]));
     }
 
-    public function testPost()
+    public function testPost(): void
     {
         $this->assertInstanceOf(Response::class, $this->api->post('post', ['request-param' => 123]));
     }
 
-    public function testApiClientException()
+    public function testApiClientException(): void
     {
         $mock = new MockHandler([
             new ClientException('a', new Request('POST', 'test')),
@@ -69,7 +69,7 @@ public function testApiClientException()
         $api->post('post', ['request-param' => 123]);
     }
 
-    public function testConnectionException()
+    public function testConnectionException(): void
     {
         $mock = new MockHandler([
             new ConnectException('Error Communicating with Server', new Request('POST', 'test')),
@@ -84,7 +84,7 @@ public function testConnectionException()
         $api->post('post', ['request-param' => 123]);
     }
 
-    public function testAlreadyRenewedException()
+    public function testAlreadyRenewedException(): void
     {
         $mock = new MockHandler([
             new ServerException('Domain already renewed.', new Request('POST', 'test')),
@@ -99,7 +99,7 @@ public function testAlreadyRenewedException()
         $api->post('post', ['request-param' => 123]);
     }
 
-    public function testApiException()
+    public function testApiException(): void
     {
         $mock = new MockHandler([
             new RequestException('Error Communicating with Server', new Request('POST', 'test')),
@@ -114,22 +114,22 @@ public function testApiException()
         $api->post('post', ['request-param' => 123]);
     }
 
-    public function testBusinessEmailOrder()
+    public function testBusinessEmailOrder(): void
     {
         $this->assertInstanceOf(BusinessEmailOrder::class, $this->api->businessEmailOrder());
     }
 
-    public function testDomainOrder()
+    public function testDomainOrder(): void
     {
         $this->assertInstanceOf(DomainOrder::class, $this->api->domainOrder());
     }
 
-    public function testEmailAccount()
+    public function testEmailAccount(): void
     {
         $this->assertInstanceOf(EmailAccount::class, $this->api->emailAccount());
     }
 
-    public function testEmailForwarder()
+    public function testEmailForwarder(): void
     {
         $this->assertInstanceOf(EmailForwarder::class, $this->api->emailForwarder());
     }
diff --git a/tests/unit/ConfigTest.php b/tests/unit/ConfigTest.php
index e05ba0c..aa53215 100644
--- a/tests/unit/ConfigTest.php
+++ b/tests/unit/ConfigTest.php
@@ -12,28 +12,28 @@ class ConfigTest extends TestCase
      */
     private $config;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->config = new Config(123, 'api_key');
     }
 
-    public function testAuthUserId()
+    public function testAuthUserId(): void
     {
         $this->assertEquals(123, $this->config->authUserId());
     }
 
-    public function testApiKey()
+    public function testApiKey(): void
     {
         $this->assertEquals('api_key', $this->config->apiKey());
     }
 
-    public function testIsNotTestMode()
+    public function testIsNotTestMode(): void
     {
         $this->assertFalse($this->config->isTestMode());
     }
 
-    public function testIsTestMode()
+    public function testIsTestMode(): void
     {
         $config = new Config(123, 'api_key', true);
         $this->assertTrue($config->isTestMode());
diff --git a/tests/unit/Dns/A/ARecordTest.php b/tests/unit/Dns/A/ARecordTest.php
index 8855211..b105b8b 100644
--- a/tests/unit/Dns/A/ARecordTest.php
+++ b/tests/unit/Dns/A/ARecordTest.php
@@ -19,7 +19,7 @@
 
 class ARecordTest extends TestCase
 {
-    public function testAddInstance()
+    public function testAddInstance(): void
     {
         $ARecord = new ARecord($this->api($this->mockResponse()));
 
@@ -33,7 +33,7 @@ public function testAddInstance()
         $this->assertInstanceOf(AddResponse::class, $ARecord->add($addRequest));
     }
 
-    public function testUpdateInstance()
+    public function testUpdateInstance(): void
     {
         $ARecord = new ARecord($this->api($this->mockResponse()));
 
diff --git a/tests/unit/Dns/A/Requests/AddRequestTest.php b/tests/unit/Dns/A/Requests/AddRequestTest.php
index 5328392..47c5053 100644
--- a/tests/unit/Dns/A/Requests/AddRequestTest.php
+++ b/tests/unit/Dns/A/Requests/AddRequestTest.php
@@ -9,7 +9,7 @@
 
 class AddRequestTest extends TestCase
 {
-    public function testInstantiation()
+    public function testInstantiation(): void
     {
         $ttl = TimeToLive::defaultTtl();
         $request = new AddRequest(
@@ -22,7 +22,7 @@ public function testInstantiation()
         $this->assertInstanceOf(AddRequest::class, $request);
     }
 
-    public function testInstantiationWithoutTTL()
+    public function testInstantiationWithoutTTL(): void
     {
         $request = new AddRequest(
             'test.com',
@@ -33,7 +33,7 @@ public function testInstantiationWithoutTTL()
         $this->assertInstanceOf(AddRequest::class, $request);
     }
 
-    public function testGetters()
+    public function testGetters(): void
     {
         $ttl = TimeToLive::defaultTtl();
         $request = new AddRequest(
@@ -43,13 +43,13 @@ public function testGetters()
             $ttl
         );
 
-        $this->assertInternalType('string', $request->domain());
-        $this->assertInternalType('string', $request->record());
+        $this->assertIsString($request->domain());
+        $this->assertIsString($request->record());
         $this->assertInstanceOf(IPv4Address::class, $request->value());
         $this->assertInstanceOf(TimeToLive::class, $request->ttl());
     }
 
-    public function testGettersWithoutTTL()
+    public function testGettersWithoutTTL(): void
     {
         $request = new AddRequest(
             'test.com',
@@ -57,14 +57,14 @@ public function testGettersWithoutTTL()
             new IPv4Address('127.0.0.1')
         );
 
-        $this->assertInternalType('string', $request->domain());
-        $this->assertInternalType('string', $request->record());
+        $this->assertIsString($request->domain());
+        $this->assertIsString($request->record());
         $this->assertInstanceOf(IPv4Address::class, $request->value());
         $this->assertInstanceOf(TimeToLive::class, $request->ttl());
         $this->assertEquals((string) $request->ttl(), TimeToLive::DEFAULT_TTL);
     }
 
-    public function testGettersWithBlankRecord()
+    public function testGettersWithBlankRecord(): void
     {
         $ttl = TimeToLive::defaultTtl();
         $request = new AddRequest(
@@ -74,8 +74,8 @@ public function testGettersWithBlankRecord()
             $ttl
         );
 
-        $this->assertInternalType('string', $request->domain());
-        $this->assertInternalType('string', $request->record());
+        $this->assertIsString($request->domain());
+        $this->assertIsString($request->record());
         $this->assertInstanceOf(IPv4Address::class, $request->value());
         $this->assertInstanceOf(TimeToLive::class, $request->ttl());
     }
diff --git a/tests/unit/Dns/A/Requests/UpdateRequestTest.php b/tests/unit/Dns/A/Requests/UpdateRequestTest.php
index 6d8f0a4..f55bf67 100644
--- a/tests/unit/Dns/A/Requests/UpdateRequestTest.php
+++ b/tests/unit/Dns/A/Requests/UpdateRequestTest.php
@@ -9,7 +9,7 @@
 
 class UpdateRequestTest extends TestCase
 {
-    public function testInstantiation()
+    public function testInstantiation(): void
     {
         $ttl = TimeToLive::defaultTtl();
         $request = new UpdateRequest(
@@ -23,7 +23,7 @@ public function testInstantiation()
         $this->assertInstanceOf(UpdateRequest::class, $request);
     }
 
-    public function testInstantiationWithoutTTL()
+    public function testInstantiationWithoutTTL(): void
     {
         $request = new UpdateRequest(
             'test.com',
@@ -35,7 +35,7 @@ public function testInstantiationWithoutTTL()
         $this->assertInstanceOf(UpdateRequest::class, $request);
     }
 
-    public function testGetters()
+    public function testGetters(): void
     {
         $ttl = TimeToLive::defaultTtl();
         $request = new UpdateRequest(
@@ -46,14 +46,14 @@ public function testGetters()
             $ttl
         );
 
-        $this->assertInternalType('string', $request->domain());
-        $this->assertInternalType('string', $request->record());
+        $this->assertIsString($request->domain());
+        $this->assertIsString($request->record());
         $this->assertInstanceOf(IPv4Address::class, $request->currentValue());
         $this->assertInstanceOf(IPv4Address::class, $request->newValue());
         $this->assertInstanceOf(TimeToLive::class, $request->ttl());
     }
 
-    public function testGettersWithoutTTL()
+    public function testGettersWithoutTTL(): void
     {
         $request = new UpdateRequest(
             'test.com',
@@ -62,8 +62,8 @@ public function testGettersWithoutTTL()
             new IPv4Address('192.168.0.1')
         );
 
-        $this->assertInternalType('string', $request->domain());
-        $this->assertInternalType('string', $request->record());
+        $this->assertIsString($request->domain());
+        $this->assertIsString($request->record());
         $this->assertInstanceOf(IPv4Address::class, $request->currentValue());
         $this->assertInstanceOf(IPv4Address::class, $request->newValue());
         $this->assertInstanceOf(TimeToLive::class, $request->ttl());
diff --git a/tests/unit/Dns/Cname/CnameRecordTest.php b/tests/unit/Dns/Cname/CnameRecordTest.php
index 2031dbd..bc75b22 100644
--- a/tests/unit/Dns/Cname/CnameRecordTest.php
+++ b/tests/unit/Dns/Cname/CnameRecordTest.php
@@ -18,7 +18,7 @@
 
 class CnameRecordTest extends TestCase
 {
-    public function testAddInstance()
+    public function testAddInstance(): void
     {
         $cnameRecord = new CnameRecord($this->api($this->mockResponse()));
 
@@ -32,7 +32,7 @@ public function testAddInstance()
         $this->assertInstanceOf(AddResponse::class, $cnameRecord->add($addRequest));
     }
 
-    public function testUpdateInstance()
+    public function testUpdateInstance(): void
     {
         $cnameRecord = new CnameRecord($this->api($this->mockResponse()));
 
diff --git a/tests/unit/Dns/Cname/Requests/AddRequestTest.php b/tests/unit/Dns/Cname/Requests/AddRequestTest.php
index c3c469f..f0d0f72 100644
--- a/tests/unit/Dns/Cname/Requests/AddRequestTest.php
+++ b/tests/unit/Dns/Cname/Requests/AddRequestTest.php
@@ -8,7 +8,7 @@
 
 class AddRequestTest extends TestCase
 {
-    public function testInstantiation()
+    public function testInstantiation(): void
     {
         $ttl = TimeToLive::defaultTtl();
         $request = new AddRequest(
@@ -21,7 +21,7 @@ public function testInstantiation()
         $this->assertInstanceOf(AddRequest::class, $request);
     }
 
-    public function testInstantiationWithoutTTL()
+    public function testInstantiationWithoutTTL(): void
     {
         $request = new AddRequest(
             'test.com',
@@ -32,7 +32,7 @@ public function testInstantiationWithoutTTL()
         $this->assertInstanceOf(AddRequest::class, $request);
     }
 
-    public function testGetters()
+    public function testGetters(): void
     {
         $ttl = TimeToLive::defaultTtl();
         $request = new AddRequest(
@@ -42,13 +42,13 @@ public function testGetters()
             $ttl
         );
 
-        $this->assertInternalType('string', $request->domain());
-        $this->assertInternalType('string', $request->record());
-        $this->assertInternalType('string', $request->value());
+        $this->assertIsString($request->domain());
+        $this->assertIsString($request->record());
+        $this->assertIsString($request->value());
         $this->assertInstanceOf(TimeToLive::class, $request->ttl());
     }
 
-    public function testGettersWithoutTTL()
+    public function testGettersWithoutTTL(): void
     {
         $request = new AddRequest(
             'test.com',
@@ -56,9 +56,9 @@ public function testGettersWithoutTTL()
             'cname.new.com'
         );
 
-        $this->assertInternalType('string', $request->domain());
-        $this->assertInternalType('string', $request->record());
-        $this->assertInternalType('string', $request->value());
+        $this->assertIsString($request->domain());
+        $this->assertIsString($request->record());
+        $this->assertIsString($request->value());
         $this->assertInstanceOf(TimeToLive::class, $request->ttl());
         $this->assertEquals((string) $request->ttl(), TimeToLive::DEFAULT_TTL);
     }
diff --git a/tests/unit/Dns/Cname/Requests/UpdateRequestTest.php b/tests/unit/Dns/Cname/Requests/UpdateRequestTest.php
index 1214b97..0aaa15f 100644
--- a/tests/unit/Dns/Cname/Requests/UpdateRequestTest.php
+++ b/tests/unit/Dns/Cname/Requests/UpdateRequestTest.php
@@ -8,7 +8,7 @@
 
 class UpdateRequestTest extends TestCase
 {
-    public function testInstantiation()
+    public function testInstantiation(): void
     {
         $ttl = TimeToLive::defaultTtl();
         $request = new UpdateRequest(
@@ -22,7 +22,7 @@ public function testInstantiation()
         $this->assertInstanceOf(UpdateRequest::class, $request);
     }
 
-    public function testInstantiationWithoutTTL()
+    public function testInstantiationWithoutTTL(): void
     {
         $request = new UpdateRequest(
             'test.com',
@@ -45,14 +45,14 @@ public function testGetters()
             $ttl
         );
 
-        $this->assertInternalType('string', $request->domain());
-        $this->assertInternalType('string', $request->record());
-        $this->assertInternalType('string', $request->currentValue());
-        $this->assertInternalType('string', $request->newValue());
+        $this->assertIsString($request->domain());
+        $this->assertIsString($request->record());
+        $this->assertIsString($request->currentValue());
+        $this->assertIsString($request->newValue());
         $this->assertInstanceOf(TimeToLive::class, $request->ttl());
     }
 
-    public function testGettersWithoutTTL()
+    public function testGettersWithoutTTL(): void
     {
         $request = new UpdateRequest(
             'test.com',
@@ -61,10 +61,10 @@ public function testGettersWithoutTTL()
             'cname.new.com'
         );
 
-        $this->assertInternalType('string', $request->domain());
-        $this->assertInternalType('string', $request->record());
-        $this->assertInternalType('string', $request->currentValue());
-        $this->assertInternalType('string', $request->newValue());
+        $this->assertIsString($request->domain());
+        $this->assertIsString($request->record());
+        $this->assertIsString($request->currentValue());
+        $this->assertIsString($request->newValue());
         $this->assertInstanceOf(TimeToLive::class, $request->ttl());
         $this->assertEquals((string) $request->ttl(), TimeToLive::DEFAULT_TTL);
     }
diff --git a/tests/unit/EmailAddressTest.php b/tests/unit/EmailAddressTest.php
index 35a3d88..da1ed70 100644
--- a/tests/unit/EmailAddressTest.php
+++ b/tests/unit/EmailAddressTest.php
@@ -8,14 +8,14 @@
 
 class EmailAddressTest extends TestCase
 {
-    public function testCanCreateNewInstance()
+    public function testCanCreateNewInstance(): void
     {
         $email = new EmailAddress('steve@apple.com');
 
         $this->assertEquals('steve@apple.com', (string) $email);
     }
 
-    public function testInvalidEmailAddressThrowsException()
+    public function testInvalidEmailAddressThrowsException(): void
     {
         $this->expectException(InvalidArgumentException::class);
 
diff --git a/tests/unit/ExceptionMapperTest.php b/tests/unit/ExceptionMapperTest.php
index 509f818..25965ff 100644
--- a/tests/unit/ExceptionMapperTest.php
+++ b/tests/unit/ExceptionMapperTest.php
@@ -24,13 +24,13 @@ class ExceptionMapperTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->request = new Request('GET', 'https://test');
     }
 
-    public function testApiClientException()
+    public function testApiClientException(): void
     {
         $expectedMessage = 'Authentication failure';
         $expectedCode = 400;
@@ -49,7 +49,7 @@ public function testApiClientException()
         $this->assertEquals($expectedMessage, $exception->getMessage());
     }
 
-    public function testConnectionException()
+    public function testConnectionException(): void
     {
         $expectedMessage = 'Authentication failure';
 
@@ -66,7 +66,7 @@ public function testConnectionException()
         $this->assertEquals($expectedMessage, $exception->getMessage());
     }
 
-    public function testApiException()
+    public function testApiException(): void
     {
         $expectedMessage = 'Some base message.';
         $expectedCode = 500;
@@ -85,7 +85,7 @@ public function testApiException()
         $this->assertEquals($expectedMessage, $exception->getMessage());
     }
 
-    public function testAlreadyRenewedException()
+    public function testAlreadyRenewedException(): void
     {
         $expectedMessage = 'Domain already renewed.';
         $expectedCode = 500;
@@ -104,7 +104,7 @@ public function testAlreadyRenewedException()
         $this->assertEquals($expectedMessage, $exception->getMessage());
     }
 
-    public function testActionPendingException()
+    public function testActionPendingException(): void
     {
         $expectedMessage = 'There is already an action pending on this Order.';
         $expectedCode = 500;
@@ -123,7 +123,7 @@ public function testActionPendingException()
         $this->assertEquals($expectedMessage, $exception->getMessage());
     }
 
-    public function testMinimumRequirementException()
+    public function testMinimumRequirementException(): void
     {
         $expectedMessage = 'You must have atleast ONE email account.';
         $expectedCode = 500;
@@ -142,7 +142,7 @@ public function testMinimumRequirementException()
         $this->assertEquals($expectedMessage, $exception->getMessage());
     }
 
-    private function response($expectedCode, $expectedMessage)
+    private function response($expectedCode, $expectedMessage): Response
     {
         return new Response($expectedCode, [], json_encode(['status' => 'Error', 'message' => $expectedMessage]));
     }
diff --git a/tests/unit/IPv4AddressTest.php b/tests/unit/IPv4AddressTest.php
index 153af71..f873ac3 100644
--- a/tests/unit/IPv4AddressTest.php
+++ b/tests/unit/IPv4AddressTest.php
@@ -8,14 +8,14 @@
 
 class IPv4AddressTest extends TestCase
 {
-    public function testCanCreateNewInstance()
+    public function testCanCreateNewInstance(): void
     {
         $address = new IPv4Address('127.0.0.1');
 
         $this->assertEquals('127.0.0.1', (string) $address);
     }
 
-    public function testInvalidIPv4AddressThrowsException()
+    public function testInvalidIPv4AddressThrowsException(): void
     {
         $this->expectException(InvalidArgumentException::class);
 
@@ -25,7 +25,7 @@ public function testInvalidIPv4AddressThrowsException()
         new IPv4Address('127.0.0');
     }
 
-    public function testInvalidIPv4AddressThrowsException2()
+    public function testInvalidIPv4AddressThrowsException2(): void
     {
         $this->expectException(InvalidArgumentException::class);
 
@@ -35,7 +35,7 @@ public function testInvalidIPv4AddressThrowsException2()
         new IPv4Address('127.0.0.0.1');
     }
 
-    public function testInvalidIPv4AddressThrowsException3()
+    public function testInvalidIPv4AddressThrowsException3(): void
     {
         $this->expectException(InvalidArgumentException::class);
 
diff --git a/tests/unit/MessageTest.php b/tests/unit/MessageTest.php
index 9f63d8a..964096d 100644
--- a/tests/unit/MessageTest.php
+++ b/tests/unit/MessageTest.php
@@ -7,7 +7,7 @@
 
 class MessageTest extends TestCase
 {
-    public function testMessageReturnsCorrectString()
+    public function testMessageReturnsCorrectString(): void
     {
         $this->assertEquals('This is the message', (string) new Message('This is the message'));
     }
diff --git a/tests/unit/Orders/BusinessEmails/BusinessEmailOrderTest.php b/tests/unit/Orders/BusinessEmails/BusinessEmailOrderTest.php
index b5dd4fe..9d28c33 100644
--- a/tests/unit/Orders/BusinessEmails/BusinessEmailOrderTest.php
+++ b/tests/unit/Orders/BusinessEmails/BusinessEmailOrderTest.php
@@ -23,7 +23,7 @@
 
 class BusinessEmailOrderTest extends TestCase
 {
-    public function testResponseFromBusinessEmailOrderCreate()
+    public function testResponseFromBusinessEmailOrderCreate(): void
     {
         $mock = new MockHandler([
             new Response(
@@ -62,7 +62,7 @@ public function testResponseFromBusinessEmailOrderCreate()
         );
     }
 
-    public function testResponseFromBusinessEmailOrderDelete()
+    public function testResponseFromBusinessEmailOrderDelete(): void
     {
         $mock = new MockHandler([
             new Response(
@@ -90,7 +90,7 @@ public function testResponseFromBusinessEmailOrderDelete()
         );
     }
 
-    public function testResponseFromBusinessEmailOrderGet()
+    public function testResponseFromBusinessEmailOrderGet(): void
     {
         $mock = new MockHandler([
             new Response(
@@ -138,7 +138,7 @@ public function testResponseFromBusinessEmailOrderGet()
         );
     }
 
-    public function testResponseFromBusinessEmailOrderAddEmailAccount()
+    public function testResponseFromBusinessEmailOrderAddEmailAccount(): void
     {
         $mock = new MockHandler([
             new Response(
@@ -178,7 +178,7 @@ public function testResponseFromBusinessEmailOrderAddEmailAccount()
         );
     }
 
-    public function testResponseFromBusinessEmailOrderDeleteEmailAccount()
+    public function testResponseFromBusinessEmailOrderDeleteEmailAccount(): void
     {
         $mock = new MockHandler([
             new Response(
diff --git a/tests/unit/Orders/BusinessEmails/Requests/AddEmailAccountRequestTest.php b/tests/unit/Orders/BusinessEmails/Requests/AddEmailAccountRequestTest.php
index 873d091..e63de75 100644
--- a/tests/unit/Orders/BusinessEmails/Requests/AddEmailAccountRequestTest.php
+++ b/tests/unit/Orders/BusinessEmails/Requests/AddEmailAccountRequestTest.php
@@ -14,7 +14,7 @@ class AddEmailAccountRequestTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -29,12 +29,12 @@ protected function setUp()
         );
     }
 
-    public function testItCanGetOrderId()
+    public function testItCanGetOrderId(): void
     {
         $this->assertEquals(123, $this->request->orderId());
     }
 
-    public function testItCanGetNumberOfAccounts()
+    public function testItCanGetNumberOfAccounts(): void
     {
         $this->assertEquals(1, $this->request->numberOfAccounts());
     }
diff --git a/tests/unit/Orders/BusinessEmails/Requests/BusinessEmailOrderRequestTest.php b/tests/unit/Orders/BusinessEmails/Requests/BusinessEmailOrderRequestTest.php
index 679a724..cd00c11 100644
--- a/tests/unit/Orders/BusinessEmails/Requests/BusinessEmailOrderRequestTest.php
+++ b/tests/unit/Orders/BusinessEmails/Requests/BusinessEmailOrderRequestTest.php
@@ -13,7 +13,7 @@ class BusinessEmailOrderRequestTest extends TestCase
      */
     private $businessEmailOrder;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -26,30 +26,30 @@ protected function setUp()
         );
     }
 
-    public function testCustomerId()
+    public function testCustomerId(): void
     {
         $customerId = $this->businessEmailOrder->customerId();
 
-        $this->assertInternalType('int', $customerId);
+        $this->assertIsInt($customerId);
         $this->assertEquals(123, $customerId);
     }
 
-    public function testDomainName()
+    public function testDomainName(): void
     {
         $this->assertEquals('some-domain.co.uk', $this->businessEmailOrder->domain());
     }
 
-    public function testNumberOfAccounts()
+    public function testNumberOfAccounts(): void
     {
         $numberOfAccounts = $this->businessEmailOrder->numberOfAccounts();
-        $this->assertInternalType('int', $numberOfAccounts);
+        $this->assertIsInt($numberOfAccounts);
         $this->assertEquals(5, $numberOfAccounts);
     }
 
-    public function testForNumberOfMonths()
+    public function testForNumberOfMonths(): void
     {
         $forNumberOfMonths = $this->businessEmailOrder->forNumberOfMonths();
-        $this->assertInternalType('int', $forNumberOfMonths);
+        $this->assertIsInt($forNumberOfMonths);
         $this->assertEquals(1, $forNumberOfMonths);
     }
 
diff --git a/tests/unit/Orders/BusinessEmails/Requests/DeleteEmailAccountRequestTest.php b/tests/unit/Orders/BusinessEmails/Requests/DeleteEmailAccountRequestTest.php
index 760afed..9edf086 100644
--- a/tests/unit/Orders/BusinessEmails/Requests/DeleteEmailAccountRequestTest.php
+++ b/tests/unit/Orders/BusinessEmails/Requests/DeleteEmailAccountRequestTest.php
@@ -13,7 +13,7 @@ class DeleteEmailAccountRequestTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -25,12 +25,12 @@ protected function setUp()
         );
     }
 
-    public function testItCanGetOrderId()
+    public function testItCanGetOrderId(): void
     {
         $this->assertEquals(123, $this->request->orderId());
     }
 
-    public function testItCanGetNumberOfAccounts()
+    public function testItCanGetNumberOfAccounts(): void
     {
         $this->assertEquals(1, $this->request->numberOfAccounts());
     }
diff --git a/tests/unit/Orders/BusinessEmails/Requests/RenewRequestTest.php b/tests/unit/Orders/BusinessEmails/Requests/RenewRequestTest.php
index 56a7eff..c775e48 100644
--- a/tests/unit/Orders/BusinessEmails/Requests/RenewRequestTest.php
+++ b/tests/unit/Orders/BusinessEmails/Requests/RenewRequestTest.php
@@ -14,7 +14,7 @@ class RenewRequestTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -30,22 +30,22 @@ protected function setUp()
         );
     }
 
-    public function testItCanGetOrderId()
+    public function testItCanGetOrderId(): void
     {
         $this->assertEquals(123, $this->request->orderId());
     }
 
-    public function testItCanGetMonths()
+    public function testItCanGetMonths(): void
     {
         $this->assertEquals(3, $this->request->months());
     }
 
-    public function testItCanGetNumberOfAccounts()
+    public function testItCanGetNumberOfAccounts(): void
     {
         $this->assertEquals(0, $this->request->numberOfAccounts());
     }
 
-    public function testItCanGetInvoiceOption()
+    public function testItCanGetInvoiceOption(): void
     {
         $this->assertInstanceOf(InvoiceOption::class, $this->request->invoiceOption());
         $this->assertEquals('NoInvoice', (string) $this->request->invoiceOption());
diff --git a/tests/unit/Orders/BusinessEmails/Responses/AddedEmailAccountResponseFactoryTest.php b/tests/unit/Orders/BusinessEmails/Responses/AddedEmailAccountResponseFactoryTest.php
index c6cffb4..b233a08 100644
--- a/tests/unit/Orders/BusinessEmails/Responses/AddedEmailAccountResponseFactoryTest.php
+++ b/tests/unit/Orders/BusinessEmails/Responses/AddedEmailAccountResponseFactoryTest.php
@@ -9,7 +9,7 @@
 
 class AddedEmailAccountResponseFactoryTest extends TestCase
 {
-    public function testPayInvoiceResponse()
+    public function testPayInvoiceResponse(): void
     {
         $responseBody = [
             'actionstatusdesc'        => 'Request will be processed in some time.',
@@ -42,7 +42,7 @@ public function testPayInvoiceResponse()
         }
     }
 
-    public function testKeepInvoiceResponse()
+    public function testKeepInvoiceResponse(): void
     {
         $responseBody = [
             'actionstatusdesc'        => 'Request will be processed in some time.',
@@ -75,7 +75,7 @@ public function testKeepInvoiceResponse()
         }
     }
 
-    public function testOnlyAddResponse()
+    public function testOnlyAddResponse(): void
     {
         $responseBody = [
             'customercost' => '90.54',
@@ -99,7 +99,7 @@ public function testOnlyAddResponse()
         }
     }
 
-    public function testNoInvoiceResponse()
+    public function testNoInvoiceResponse(): void
     {
         $responseBody = [
             'entityid'         => '80064711',
diff --git a/tests/unit/Orders/BusinessEmails/Responses/AddedEmailAccountResponseTest.php b/tests/unit/Orders/BusinessEmails/Responses/AddedEmailAccountResponseTest.php
index a778b2e..149a558 100644
--- a/tests/unit/Orders/BusinessEmails/Responses/AddedEmailAccountResponseTest.php
+++ b/tests/unit/Orders/BusinessEmails/Responses/AddedEmailAccountResponseTest.php
@@ -16,7 +16,7 @@ class AddedEmailAccountResponseTest extends TestCase
      */
     private $response;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -38,7 +38,7 @@ protected function setUp()
         ]);
     }
 
-    public function testItCanGetAction()
+    public function testItCanGetAction(): void
     {
         $this->assertInstanceOf(Action::class, $this->response->action());
         $this->assertEquals(469754540, $this->response->action()->id());
@@ -51,55 +51,55 @@ public function testItCanGetAction()
         $this->assertEquals('Request will be processed in some time.', $this->response->action()->statusDescription());
     }
 
-    public function testItCanGetEntityId()
+    public function testItCanGetEntityId(): void
     {
         $this->assertEquals(80030154, $this->response->entityId());
     }
 
-    public function testItCanGetDomain()
+    public function testItCanGetDomain(): void
     {
         $this->assertEquals('test-domain.co.uk.onlyfordemo.com', $this->response->domain());
     }
 
-    public function testItCanGetStatus()
+    public function testItCanGetStatus(): void
     {
         $this->assertInstanceOf(Status::class, $this->response->status());
         $this->assertEquals('success', (string) $this->response->status());
     }
 
-    public function testItCanGetInvoiceId()
+    public function testItCanGetInvoiceId(): void
     {
         $this->assertEquals(78877737, $this->response->invoiceId());
     }
 
-    public function testItCanGetCustomerId()
+    public function testItCanGetCustomerId(): void
     {
         $this->assertEquals(17824872, $this->response->customerId());
     }
 
-    public function testItCanGetSellingCurrencySymbol()
+    public function testItCanGetSellingCurrencySymbol(): void
     {
         $this->assertEquals('GBP', $this->response->sellingCurrencySymbol());
     }
 
-    public function testItCanGetSellingCurrency()
+    public function testItCanGetSellingCurrency(): void
     {
         $this->assertInstanceOf(Currency::class, $this->response->sellingCurrency());
     }
 
-    public function testItCanGetSellingAmount()
+    public function testItCanGetSellingAmount(): void
     {
         $this->assertInstanceOf(Money::class, $this->response->sellingAmount());
         $this->assertEquals('-9054', $this->response->sellingAmount()->getAmount());
     }
 
-    public function testItCanGetUnutilisedSellingAmount()
+    public function testItCanGetUnutilisedSellingAmount(): void
     {
         $this->assertInstanceOf(Money::class, $this->response->unutilisedSellingAmount());
         $this->assertEquals('-9054', $this->response->unutilisedSellingAmount()->getAmount());
     }
 
-    public function testItCanGetCustomerCost()
+    public function testItCanGetCustomerCost(): void
     {
         $this->assertInstanceOf(Money::class, $this->response->customerCost());
         $this->assertEquals('9054', $this->response->customerCost()->getAmount());
diff --git a/tests/unit/Orders/BusinessEmails/Responses/BusinessEmailOrderResponseTest.php b/tests/unit/Orders/BusinessEmails/Responses/BusinessEmailOrderResponseTest.php
index cb161a8..30da8be 100644
--- a/tests/unit/Orders/BusinessEmails/Responses/BusinessEmailOrderResponseTest.php
+++ b/tests/unit/Orders/BusinessEmails/Responses/BusinessEmailOrderResponseTest.php
@@ -13,7 +13,7 @@ class BusinessEmailOrderResponseTest extends TestCase
      */
     private $response;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -28,17 +28,17 @@ protected function setUp()
         ]);
     }
 
-    public function testItCanGetDomain()
+    public function testItCanGetDomain(): void
     {
         $this->assertEquals('some-domain.co.in', $this->response->domain());
     }
 
-    public function testItCanGetOrderId()
+    public function testItCanGetOrderId(): void
     {
         $this->assertEquals(1234, $this->response->orderId());
     }
 
-    public function testItCanGetAction()
+    public function testItCanGetAction(): void
     {
         $this->assertInstanceOf(Action::class, $this->response->action());
     }
diff --git a/tests/unit/Orders/BusinessEmails/Responses/CreateResponseTest.php b/tests/unit/Orders/BusinessEmails/Responses/CreateResponseTest.php
index c76f10b..3409932 100644
--- a/tests/unit/Orders/BusinessEmails/Responses/CreateResponseTest.php
+++ b/tests/unit/Orders/BusinessEmails/Responses/CreateResponseTest.php
@@ -15,39 +15,39 @@ class CreateResponseTest extends TestCase
      */
     private $response;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
         $this->response = $this->createResponse();
     }
 
-    public function testOrderId()
+    public function testOrderId(): void
     {
         $this->assertEquals(79767882, $this->response->orderId());
     }
 
-    public function testDomain()
+    public function testDomain(): void
     {
         $this->assertEquals('test-domain.co.uk.onlyfordemo.com', $this->response->domain());
     }
 
-    public function testItCanGetAction()
+    public function testItCanGetAction(): void
     {
         $this->assertInstanceOf(Action::class, $this->response->action());
     }
 
-    public function testInvoiceId()
+    public function testInvoiceId(): void
     {
         $this->assertEquals(77433277, $this->response->invoiceId());
     }
 
-    public function testSellingCurrencySymbol()
+    public function testSellingCurrencySymbol(): void
     {
         $this->assertEquals('GBP', $this->response->sellingCurrencySymbol());
     }
 
-    public function testSellingCurrency()
+    public function testSellingCurrency(): void
     {
         $this->assertInstanceOf(Currency::class, $this->response->sellingCurrency());
         $this->assertEquals('GBP', $this->response->sellingCurrency());
@@ -56,7 +56,7 @@ public function testSellingCurrency()
     /**
      * @dataProvider sellingAmountProvider
      */
-    public function testSellingAmount($response, $expectedAmount)
+    public function testSellingAmount($response, $expectedAmount): void
     {
         $this->assertInstanceOf(Money::class, $response->sellingAmount());
         $this->assertEquals($expectedAmount, $response->sellingAmount()->getAmount());
@@ -65,18 +65,18 @@ public function testSellingAmount($response, $expectedAmount)
     /**
      * @dataProvider transactionAmountProvider
      */
-    public function testTransactionAmount($response, $expectedAmount)
+    public function testTransactionAmount($response, $expectedAmount): void
     {
         $this->assertInstanceOf(Money::class, $response->transactionAmount());
         $this->assertEquals($expectedAmount, $response->transactionAmount()->getAmount());
     }
 
-    public function testCustomerId()
+    public function testCustomerId(): void
     {
         $this->assertEquals(17824872, $this->response->customerId());
     }
 
-    public function sellingAmountProvider()
+    public function sellingAmountProvider(): array
     {
         return [
             [
@@ -94,7 +94,7 @@ public function sellingAmountProvider()
         ];
     }
 
-    public function transactionAmountProvider()
+    public function transactionAmountProvider(): array
     {
         return [
             [
@@ -112,7 +112,7 @@ public function transactionAmountProvider()
         ];
     }
 
-    private function createResponse(array $overrides = [])
+    private function createResponse(array $overrides = []): CreateResponse
     {
         $defaults = [
             'entityid'                => '79767882',
diff --git a/tests/unit/Orders/BusinessEmails/Responses/DeletedEmailAccountResponseTest.php b/tests/unit/Orders/BusinessEmails/Responses/DeletedEmailAccountResponseTest.php
index e362e85..8e8d8d9 100644
--- a/tests/unit/Orders/BusinessEmails/Responses/DeletedEmailAccountResponseTest.php
+++ b/tests/unit/Orders/BusinessEmails/Responses/DeletedEmailAccountResponseTest.php
@@ -14,7 +14,7 @@ class DeletedEmailAccountResponseTest extends TestCase
      */
     private $response;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -30,7 +30,7 @@ protected function setUp()
         ]);
     }
 
-    public function testItCanGetAction()
+    public function testItCanGetAction(): void
     {
         $this->assertInstanceOf(Action::class, $this->response->action());
         $this->assertEquals(471836050, $this->response->action()->id());
@@ -49,17 +49,17 @@ public function testItCanGetAction()
         );
     }
 
-    public function testItCanGetEntityId()
+    public function testItCanGetEntityId(): void
     {
         $this->assertEquals(80239999, $this->response->entityId());
     }
 
-    public function testItCanGetDomain()
+    public function testItCanGetDomain(): void
     {
         $this->assertEquals('test-domain-3.co.uk.onlyfordemo.com', $this->response->domain());
     }
 
-    public function testItCanGetStatus()
+    public function testItCanGetStatus(): void
     {
         $this->assertInstanceOf(Status::class, $this->response->status());
         $this->assertEquals('success', (string) $this->response->status());
diff --git a/tests/unit/Orders/BusinessEmails/Responses/GetResponseTest.php b/tests/unit/Orders/BusinessEmails/Responses/GetResponseTest.php
index 7a96cfc..a6a96e9 100644
--- a/tests/unit/Orders/BusinessEmails/Responses/GetResponseTest.php
+++ b/tests/unit/Orders/BusinessEmails/Responses/GetResponseTest.php
@@ -14,222 +14,222 @@ class GetResponseTest extends TestCase
      */
     private $response;
 
-    public function testOrderId()
+    public function testOrderId(): void
     {
         $this->response = new GetResponse(['orderid' => 123]);
 
-        $this->assertInternalType('int', $this->response->orderId());
+        $this->assertIsInt($this->response->orderId());
         $this->assertEquals(123, $this->response->orderId());
     }
 
-    public function testOrderDescription()
+    public function testOrderDescription(): void
     {
         $this->response = new GetResponse(['description' => 'name.onlyfordemo.com']);
 
-        $this->assertInternalType('string', $this->response->orderDescription());
+        $this->assertIsString($this->response->orderDescription());
         $this->assertEquals('name.onlyfordemo.com', $this->response->orderDescription());
     }
 
-    public function testOrderCreationDate()
+    public function testOrderCreationDate(): void
     {
         $this->response = new GetResponse(['creationtime' => '1510142454']);
 
         $this->assertInstanceOf(Carbon::class, $this->response->orderCreationDate());
     }
 
-    public function testOrderSuspendedAtExpiry()
+    public function testOrderSuspendedAtExpiry(): void
     {
         $this->response = new GetResponse(['isOrderSuspendedUponExpiry' => true]);
 
-        $this->assertInternalType('bool', $this->response->orderSuspendedAtExpiry());
+        $this->assertIsBool($this->response->orderSuspendedAtExpiry());
         $this->assertTrue($this->response->orderSuspendedAtExpiry());
     }
 
-    public function testOrderSuspendedByParent()
+    public function testOrderSuspendedByParent(): void
     {
         $this->response = new GetResponse(['orderSuspendedByParent' => true]);
 
-        $this->assertInternalType('bool', $this->response->orderSuspendedByParent());
+        $this->assertIsBool($this->response->orderSuspendedByParent());
         $this->assertTrue($this->response->orderSuspendedByParent());
     }
 
-    public function testOrderDeletionAllowed()
+    public function testOrderDeletionAllowed(): void
     {
         $this->response = new GetResponse(['allowdeletion' => true]);
 
-        $this->assertInternalType('bool', $this->response->orderDeletionAllowed());
+        $this->assertIsBool($this->response->orderDeletionAllowed());
         $this->assertTrue($this->response->orderDeletionAllowed());
     }
 
-    public function testCurrentOrderStatus()
+    public function testCurrentOrderStatus(): void
     {
         $this->response = new GetResponse(['currentstatus' => 'Active']);
 
         $this->assertInstanceOf(OrderStatus::class, $this->response->currentOrderStatus());
     }
 
-    public function testDomain()
+    public function testDomain(): void
     {
         $this->response = new GetResponse(['domainname' => 'name.onlyfordemo.com']);
 
-        $this->assertInternalType('string', $this->response->domain());
+        $this->assertIsString($this->response->domain());
         $this->assertEquals('name.onlyfordemo.com', $this->response->domain());
     }
 
-    public function testExpiry()
+    public function testExpiry(): void
     {
         $this->response = new GetResponse(['endtime' => '1512734454']);
 
         $this->assertInstanceOf(Carbon::class, $this->response->expiry());
     }
 
-    public function testIsImmediateReseller()
+    public function testIsImmediateReseller(): void
     {
         $this->response = new GetResponse(['isImmediateReseller' => true]);
 
-        $this->assertInternalType('bool', $this->response->isImmediateReseller());
+        $this->assertIsBool($this->response->isImmediateReseller());
         $this->assertTrue($this->response->isImmediateReseller());
     }
 
-    public function testResellerParentId()
+    public function testResellerParentId(): void
     {
         $this->response = new GetResponse(['parentkey' => '999999999_999999998_715226']);
 
-        $this->assertInternalType('string', $this->response->resellerParentId());
+        $this->assertIsString($this->response->resellerParentId());
         $this->assertEquals('999999999_999999998_715226', $this->response->resellerParentId());
     }
 
-    public function testCustomerId()
+    public function testCustomerId(): void
     {
         $this->response = new GetResponse(['customerid' => '17824872']);
 
-        $this->assertInternalType('int', $this->response->customerId());
+        $this->assertIsInt($this->response->customerId());
         $this->assertEquals(17824872, $this->response->customerId());
     }
 
-    public function testNumberOfEmailAccounts()
+    public function testNumberOfEmailAccounts(): void
     {
         $this->response = new GetResponse(['emailaccounts' => 5]);
 
-        $this->assertInternalType('int', $this->response->numberOfEmailAccounts());
+        $this->assertIsInt($this->response->numberOfEmailAccounts());
         $this->assertEquals(5, $this->response->numberOfEmailAccounts());
     }
 
-    public function testProductId()
+    public function testProductId(): void
     {
         $this->response = new GetResponse(['productkey' => 'eeliteus']);
 
-        $this->assertInternalType('string', $this->response->productId());
+        $this->assertIsString($this->response->productId());
         $this->assertEquals('eeliteus', $this->response->productId());
     }
 
-    public function testProductCategory()
+    public function testProductCategory(): void
     {
         $this->response = new GetResponse(['productcategory' => 'hosting']);
 
-        $this->assertInternalType('string', $this->response->productCategory());
+        $this->assertIsString($this->response->productCategory());
         $this->assertEquals('hosting', $this->response->productCategory());
     }
 
-    public function testEntityId()
+    public function testEntityId(): void
     {
         $this->response = new GetResponse(['entityid' => 123]);
 
-        $this->assertInternalType('int', $this->response->entityId());
+        $this->assertIsInt($this->response->entityId());
         $this->assertEquals(123, $this->response->entityId());
     }
 
-    public function testEaqId()
+    public function testEaqId(): void
     {
         $this->response = new GetResponse(['eaqid' => 0]);
 
-        $this->assertInternalType('int', $this->response->eaqId());
+        $this->assertIsInt($this->response->eaqId());
         $this->assertEquals(0, $this->response->eaqId());
     }
 
-    public function testPaused()
+    public function testPaused(): void
     {
         $this->response = new GetResponse(['paused' => false]);
 
-        $this->assertInternalType('bool', $this->response->paused());
+        $this->assertIsBool($this->response->paused());
         $this->assertFalse($this->response->paused());
     }
 
-    public function testCustomerCost()
+    public function testCustomerCost(): void
     {
         $this->response = new GetResponse(['customercost' => '0.0']);
 
-        $this->assertInternalType('float', $this->response->customerCost());
+        $this->assertIsFloat($this->response->customerCost());
         $this->assertEquals('0.00', $this->response->customerCost());
     }
 
-    public function testOrderStatus()
+    public function testOrderStatus(): void
     {
         $this->response = new GetResponse(['orderstatus' => []]);
 
-        $this->assertInternalType('array', $this->response->orderStatus());
+        $this->assertIsArray($this->response->orderStatus());
     }
 
-    public function testIsRecurring()
+    public function testIsRecurring(): void
     {
         $this->response = new GetResponse(['recurring' => false]);
 
-        $this->assertInternalType('bool', $this->response->isRecurring());
+        $this->assertIsBool($this->response->isRecurring());
         $this->assertFalse($this->response->isRecurring());
     }
 
-    public function testEntityTypeId()
+    public function testEntityTypeId(): void
     {
         $this->response = new GetResponse(['entitytypeid' => 283]);
 
-        $this->assertInternalType('int', $this->response->entityTypeId());
+        $this->assertIsInt($this->response->entityTypeId());
         $this->assertEquals(283, $this->response->entityTypeId());
     }
 
-    public function testDeletionRequest()
+    public function testDeletionRequest(): void
     {
         $this->response = new GetResponse(['isDeletionRequest' => false]);
 
-        $this->assertInternalType('bool', $this->response->deletionRequest());
+        $this->assertIsBool($this->response->deletionRequest());
         $this->assertFalse($this->response->deletionRequest());
     }
 
-    public function testResellerCost()
+    public function testResellerCost(): void
     {
         $this->response = new GetResponse(['resellercost' => 0]);
 
-        $this->assertInternalType('float', $this->response->resellerCost());
+        $this->assertIsFloat($this->response->resellerCost());
         $this->assertEquals('0.00', $this->response->resellerCost());
     }
 
-    public function testJumpConditions()
+    public function testJumpConditions(): void
     {
         $this->response = new GetResponse(['jumpConditions' => []]);
 
-        $this->assertInternalType('array', $this->response->jumpConditions());
+        $this->assertIsArray($this->response->jumpConditions());
     }
 
-    public function testCurrentOrderPrice()
+    public function testCurrentOrderPrice(): void
     {
         $this->response = new GetResponse(['currentOrderPrice' => '0.0']);
 
-        $this->assertInternalType('float', $this->response->currentOrderPrice());
+        $this->assertIsFloat($this->response->currentOrderPrice());
         $this->assertEquals('0.00', $this->response->currentOrderPrice());
     }
 
-    public function testActionCompleted()
+    public function testActionCompleted(): void
     {
         $this->response = new GetResponse(['actioncompleted' => '0']);
 
-        $this->assertInternalType('string', $this->response->actionCompleted());
+        $this->assertIsString($this->response->actionCompleted());
         $this->assertEquals('0', $this->response->actionCompleted());
     }
 
-    public function testMoneyBackPeriod()
+    public function testMoneyBackPeriod(): void
     {
         $this->response = new GetResponse(['moneybackperiod' => 30]);
 
-        $this->assertInternalType('int', $this->response->moneyBackPeriod());
+        $this->assertIsInt($this->response->moneyBackPeriod());
         $this->assertEquals(30, $this->response->moneyBackPeriod());
     }
 }
diff --git a/tests/unit/Orders/BusinessEmails/Responses/RenewalResponseTest.php b/tests/unit/Orders/BusinessEmails/Responses/RenewalResponseTest.php
index 7f3f5e7..20315c0 100644
--- a/tests/unit/Orders/BusinessEmails/Responses/RenewalResponseTest.php
+++ b/tests/unit/Orders/BusinessEmails/Responses/RenewalResponseTest.php
@@ -14,7 +14,7 @@ class RenewalResponseTest extends TestCase
      */
     private $response;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -34,22 +34,22 @@ protected function setUp()
         ]);
     }
 
-    public function testItCanGetDescription()
+    public function testItCanGetDescription(): void
     {
         $this->assertEquals('Test description', $this->response->description());
     }
 
-    public function testItCanGetEntityId()
+    public function testItCanGetEntityId(): void
     {
         $this->assertEquals(123, $this->response->entityId());
     }
 
-    public function testItCanGetActionType()
+    public function testItCanGetActionType(): void
     {
         $this->assertEquals('Renew', $this->response->actiontype);
     }
 
-    public function testItCanGetActionTypeDescription()
+    public function testItCanGetActionTypeDescription(): void
     {
         $this->assertEquals(
             'Renewal of Business Email 1 for example.com for 1 month',
@@ -57,17 +57,17 @@ public function testItCanGetActionTypeDescription()
         );
     }
 
-    public function testItCanGetActionId()
+    public function testItCanGetActionId(): void
     {
         $this->assertEquals(461863406, $this->response->actionId());
     }
 
-    public function testItCanGetActionStatus()
+    public function testItCanGetActionStatus(): void
     {
         $this->assertEquals('InvoicePaid', $this->response->actionStatus());
     }
 
-    public function testItCanGetActionStatusDescription()
+    public function testItCanGetActionStatusDescription(): void
     {
         $this->assertEquals(
             'Your Order will be processed by our automatic provisioning system in the next 5-10 minutes.',
@@ -75,34 +75,34 @@ public function testItCanGetActionStatusDescription()
         );
     }
 
-    public function testItCanGetInvoiceId()
+    public function testItCanGetInvoiceId(): void
     {
         $this->assertEquals(123, $this->response->invoiceId());
     }
 
-    public function testItCanGetSellingCurrencySymbol()
+    public function testItCanGetSellingCurrencySymbol(): void
     {
         $this->assertEquals('GBP', $this->response->sellingCurrencySymbol());
     }
 
-    public function testItCanGetSellingCurrency()
+    public function testItCanGetSellingCurrency(): void
     {
         $this->assertInstanceOf(Currency::class, $this->response->sellingCurrency());
     }
 
-    public function testItCanGetSellingAmount()
+    public function testItCanGetSellingAmount(): void
     {
         $this->assertInstanceOf(Money::class, $this->response->sellingAmount());
         $this->assertEquals(1899, $this->response->sellingAmount()->getAmount());
     }
 
-    public function testItCanGetUnutilisedSellingAmount()
+    public function testItCanGetUnutilisedSellingAmount(): void
     {
         $this->assertInstanceOf(Money::class, $this->response->unutilisedSellingAmount());
         $this->assertEquals(101, $this->response->unutilisedSellingAmount()->getAmount());
     }
 
-    public function testItCanGetCustomerId()
+    public function testItCanGetCustomerId(): void
     {
         $this->assertEquals(123, $this->response->customerId());
     }
diff --git a/tests/unit/Orders/ContactTest.php b/tests/unit/Orders/ContactTest.php
index 3a59544..c2d7cc0 100644
--- a/tests/unit/Orders/ContactTest.php
+++ b/tests/unit/Orders/ContactTest.php
@@ -15,7 +15,7 @@ class ContactTest extends TestCase
      */
     private $contact;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->contact = new Contact(
@@ -43,41 +43,41 @@ protected function setUp()
         );
     }
 
-    public function testId()
+    public function testId(): void
     {
-        $this->assertInternalType('integer', $this->contact->id());
+        $this->assertIsInt($this->contact->id());
         $this->assertEquals(123, $this->contact->id());
     }
 
-    public function testCustomerId()
+    public function testCustomerId(): void
     {
-        $this->assertInternalType('integer', $this->contact->customerId());
+        $this->assertIsInt($this->contact->customerId());
         $this->assertEquals(456, $this->contact->customerId());
     }
 
-    public function testParentId()
+    public function testParentId(): void
     {
-        $this->assertInternalType('string', $this->contact->parentId());
+        $this->assertIsString($this->contact->parentId());
         $this->assertEquals('999999999_999999998_715226', $this->contact->parentId());
     }
 
-    public function testName()
+    public function testName(): void
     {
-        $this->assertInternalType('string', $this->contact->name());
+        $this->assertIsString($this->contact->name());
         $this->assertEquals('Testy McTest', $this->contact->name());
     }
 
-    public function testEmailAddress()
+    public function testEmailAddress(): void
     {
         $this->assertInstanceOf(EmailAddress::class, $this->contact->email());
     }
 
-    public function testTelephoneNumber()
+    public function testTelephoneNumber(): void
     {
         $this->assertInstanceOf(TelephoneNumber::class, $this->contact->telephoneNumber());
     }
 
-    public function testAddress()
+    public function testAddress(): void
     {
         $this->assertInstanceOf(Address::class, $this->contact->address());
     }
diff --git a/tests/unit/Orders/Domains/DelegationSignerTest.php b/tests/unit/Orders/Domains/DelegationSignerTest.php
index d168d7e..3092c46 100644
--- a/tests/unit/Orders/Domains/DelegationSignerTest.php
+++ b/tests/unit/Orders/Domains/DelegationSignerTest.php
@@ -12,7 +12,7 @@ class DelegationSignerTest extends TestCase
      */
     private $delegationSigner;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->delegationSigner = new DelegationSigner(
@@ -23,22 +23,22 @@ protected function setUp()
         );
     }
 
-    public function testKeyTag()
+    public function testKeyTag(): void
     {
         $this->assertEquals('some-key-tag', $this->delegationSigner->keyTag());
     }
 
-    public function testAlgorithm()
+    public function testAlgorithm(): void
     {
         $this->assertEquals('RSA-SHA256', $this->delegationSigner->algorithm());
     }
 
-    public function testDigest()
+    public function testDigest(): void
     {
         $this->assertEquals('some-digest', $this->delegationSigner->digest());
     }
 
-    public function testDigestType()
+    public function testDigestType(): void
     {
         $this->assertEquals('SHA-256', $this->delegationSigner->digestType());
     }
diff --git a/tests/unit/Orders/Domains/DomainOrderDetailTypeTest.php b/tests/unit/Orders/Domains/DomainOrderDetailTypeTest.php
index 9062f08..e5c7d6f 100644
--- a/tests/unit/Orders/Domains/DomainOrderDetailTypeTest.php
+++ b/tests/unit/Orders/Domains/DomainOrderDetailTypeTest.php
@@ -7,7 +7,7 @@
 
 class DomainOrderDetailTypeTest extends TestCase
 {
-    public function testValidDetailTypes()
+    public function testValidDetailTypes(): void
     {
         $this->assertInstanceOf(
             DomainOrderDetailType::class,
diff --git a/tests/unit/Orders/Domains/DomainOrderTest.php b/tests/unit/Orders/Domains/DomainOrderTest.php
index 4cfc8ff..3cf6f0b 100644
--- a/tests/unit/Orders/Domains/DomainOrderTest.php
+++ b/tests/unit/Orders/Domains/DomainOrderTest.php
@@ -22,7 +22,7 @@
 
 class DomainOrderTest extends TestCase
 {
-    public function testResponseFromDomainOrderGet()
+    public function testResponseFromDomainOrderGet(): void
     {
         $mock = new MockHandler([
             new Response(
@@ -45,7 +45,7 @@ public function testResponseFromDomainOrderGet()
         );
     }
 
-    public function testResponseFromDomainOrderGetByDomain()
+    public function testResponseFromDomainOrderGetByDomain(): void
     {
         $mock = new MockHandler([
             new Response(
@@ -68,7 +68,7 @@ public function testResponseFromDomainOrderGetByDomain()
         );
     }
 
-    public function testResponseFromDomainOrderRenew()
+    public function testResponseFromDomainOrderRenew(): void
     {
         $mock = new MockHandler([
             new Response(
diff --git a/tests/unit/Orders/Domains/NamedServersTest.php b/tests/unit/Orders/Domains/NamedServersTest.php
index 7727699..cdba44d 100644
--- a/tests/unit/Orders/Domains/NamedServersTest.php
+++ b/tests/unit/Orders/Domains/NamedServersTest.php
@@ -12,7 +12,7 @@ class NamedServersTest extends TestCase
      */
     private $namedServers;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->namedServers = new NamedServers(
@@ -23,22 +23,22 @@ protected function setUp()
         );
     }
 
-    public function testNumberOfNamedServers()
+    public function testNumberOfNamedServers(): void
     {
         $this->assertEquals(2, $this->namedServers->numberOfServers());
     }
 
-    public function testNamedServer1()
+    public function testNamedServer1(): void
     {
         $this->assertEquals('ns1.test.example.com', $this->namedServers->namedServer1());
     }
 
-    public function testNamedServer2()
+    public function testNamedServer2(): void
     {
         $this->assertEquals('ns2.testing.example.com', $this->namedServers->namedServer2());
     }
 
-    public function testChildNamedServer()
+    public function testChildNamedServer(): void
     {
         $this->assertEquals('ns3.child-named-server.example.com', $this->namedServers->childNamedServer());
     }
diff --git a/tests/unit/Orders/Domains/PrivacyProtectionTest.php b/tests/unit/Orders/Domains/PrivacyProtectionTest.php
index b1d5382..b429714 100644
--- a/tests/unit/Orders/Domains/PrivacyProtectionTest.php
+++ b/tests/unit/Orders/Domains/PrivacyProtectionTest.php
@@ -13,7 +13,7 @@ class PrivacyProtectionTest extends TestCase
      */
     private $privacyProtection;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
         $this->privacyProtection = new PrivacyProtection(
@@ -24,7 +24,7 @@ protected function setUp()
         );
     }
 
-    public function testExpiry()
+    public function testExpiry(): void
     {
         $this->assertInstanceOf(Carbon::class, $this->privacyProtection->expiry());
         $this->assertEquals(
@@ -33,17 +33,17 @@ public function testExpiry()
         );
     }
 
-    public function testRegistrantContact()
+    public function testRegistrantContact(): void
     {
         $this->assertEquals('registrant', $this->privacyProtection->registrantContact());
     }
 
-    public function testAdminContact()
+    public function testAdminContact(): void
     {
         $this->assertEquals('admin', $this->privacyProtection->adminContact());
     }
 
-    public function testBillingContact()
+    public function testBillingContact(): void
     {
         $this->assertEquals('billing', $this->privacyProtection->billingContact());
     }
diff --git a/tests/unit/Orders/Domains/RegistrantContactVerificationTest.php b/tests/unit/Orders/Domains/RegistrantContactVerificationTest.php
index 6d40370..4f3ee41 100644
--- a/tests/unit/Orders/Domains/RegistrantContactVerificationTest.php
+++ b/tests/unit/Orders/Domains/RegistrantContactVerificationTest.php
@@ -18,7 +18,7 @@ class RegistrantContactVerificationTest extends TestCase
      */
     private $verified;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -33,13 +33,13 @@ protected function setUp()
         );
     }
 
-    public function testVerificationStatus()
+    public function testVerificationStatus(): void
     {
         $this->assertEquals('Pending', $this->pendingVerification->status());
         $this->assertEquals('Verified', $this->verified->status());
     }
 
-    public function testVerificationProcessStartTimeWhenSet()
+    public function testVerificationProcessStartTimeWhenSet(): void
     {
         $this->assertInstanceOf(
             Carbon::class,
@@ -52,7 +52,7 @@ public function testVerificationProcessStartTimeWhenSet()
         );
     }
 
-    public function testVerificationProcessStartTimeWhenNotSet()
+    public function testVerificationProcessStartTimeWhenNotSet(): void
     {
         $this->assertNull(
             $this->verified->verificationProcessStartTime()
diff --git a/tests/unit/Orders/Domains/RegistryStatusTest.php b/tests/unit/Orders/Domains/RegistryStatusTest.php
index fe85ec5..b7c9139 100644
--- a/tests/unit/Orders/Domains/RegistryStatusTest.php
+++ b/tests/unit/Orders/Domains/RegistryStatusTest.php
@@ -7,31 +7,31 @@
 
 class RegistryStatusTest extends TestCase
 {
-    public function testObjectToString()
+    public function testObjectToString(): void
     {
         $this->assertEquals('resellersuspend', (string) new RegistryStatus('resellersuspend'));
         $this->assertEquals('', (string) new RegistryStatus(''));
     }
 
-    public function testIsSuspended()
+    public function testIsSuspended(): void
     {
         $this->assertTrue((new RegistryStatus('resellersuspend'))->isSuspended());
         $this->assertFalse((new RegistryStatus('not_suspended_state'))->isSuspended());
     }
 
-    public function testIsLockedAtReseller()
+    public function testIsLockedAtReseller(): void
     {
         $this->assertTrue((new RegistryStatus('resellerlock'))->isLockedAtReseller());
         $this->assertFalse((new RegistryStatus('not_locked_state'))->isLockedAtReseller());
     }
 
-    public function testIsLockedAtTransfer()
+    public function testIsLockedAtTransfer(): void
     {
         $this->assertTrue((new RegistryStatus('transferlock'))->isLockedAtTransfer());
         $this->assertFalse((new RegistryStatus('not_locked_state'))->isLockedAtTransfer());
     }
 
-    public function testIsLocked()
+    public function testIsLocked(): void
     {
         $this->assertTrue((new RegistryStatus('resellerlock'))->isLocked());
         $this->assertTrue((new RegistryStatus('transferlock'))->isLocked());
diff --git a/tests/unit/Orders/Domains/Requests/GetRequestTest.php b/tests/unit/Orders/Domains/Requests/GetRequestTest.php
index ae02177..3ffe495 100644
--- a/tests/unit/Orders/Domains/Requests/GetRequestTest.php
+++ b/tests/unit/Orders/Domains/Requests/GetRequestTest.php
@@ -19,7 +19,7 @@ class GetRequestTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -31,12 +31,12 @@ protected function setUp()
         );
     }
 
-    public function testItCanGetOrderId()
+    public function testItCanGetOrderId(): void
     {
         $this->assertEquals(123, $this->request->orderId());
     }
 
-    public function testItCanGetOrderDetailType()
+    public function testItCanGetOrderDetailType(): void
     {
         $this->assertInstanceOf(DomainOrderDetailType::class, $this->request->orderDetailType());
         $this->assertEquals((string) $this->domainOrderDetailType, $this->request->orderDetailType());
diff --git a/tests/unit/Orders/Domains/Requests/GetbyDomainRequestTest.php b/tests/unit/Orders/Domains/Requests/GetbyDomainRequestTest.php
index 248c719..153daf6 100644
--- a/tests/unit/Orders/Domains/Requests/GetbyDomainRequestTest.php
+++ b/tests/unit/Orders/Domains/Requests/GetbyDomainRequestTest.php
@@ -18,7 +18,7 @@ class GetbyDomainRequestTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -30,12 +30,12 @@ protected function setUp()
         );
     }
 
-    public function testItCanGetOrderId()
+    public function testItCanGetOrderId(): void
     {
         $this->assertEquals('some-domain.co.uk', $this->request->domain());
     }
 
-    public function testItCanGetOrderDetailType()
+    public function testItCanGetOrderDetailType(): void
     {
         $this->assertInstanceOf(DomainOrderDetailType::class, $this->request->orderDetailType());
         $this->assertEquals((string) $this->domainOrderDetailType, $this->request->orderDetailType());
diff --git a/tests/unit/Orders/Domains/Requests/RenewRequestTest.php b/tests/unit/Orders/Domains/Requests/RenewRequestTest.php
index 22e2482..15349f4 100644
--- a/tests/unit/Orders/Domains/Requests/RenewRequestTest.php
+++ b/tests/unit/Orders/Domains/Requests/RenewRequestTest.php
@@ -27,7 +27,7 @@ class RenewRequestTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -45,27 +45,27 @@ protected function setUp()
         );
     }
 
-    public function testOrderId()
+    public function testOrderId(): void
     {
-        $this->assertInternalType('int', $this->request->orderId());
+        $this->assertIsInt($this->request->orderId());
         $this->assertEquals(123, $this->request->orderId());
     }
 
-    public function testCurrentExpiryTimestamp()
+    public function testCurrentExpiryTimestamp(): void
     {
-        $this->assertInternalType('int', $this->request->currentExpiryTimestamp());
+        $this->assertIsInt($this->request->currentExpiryTimestamp());
         $this->assertEquals($this->currentExpiry->getTimestamp(), $this->request->currentExpiryTimestamp());
     }
 
-    public function testInvoiceOption()
+    public function testInvoiceOption(): void
     {
         $this->assertInstanceOf(InvoiceOption::class, $this->request->invoiceOption());
         $this->assertEquals((string) $this->invoiceOption, (string) $this->request->invoiceOption());
     }
 
-    public function testYears()
+    public function testYears(): void
     {
-        $this->assertInternalType('int', $this->request->years());
+        $this->assertIsInt($this->request->years());
         $this->assertEquals(1, $this->request->years());
 
         $this->request = new RenewRequest(
@@ -77,13 +77,13 @@ public function testYears()
             $autoRenew = false
         );
 
-        $this->assertInternalType('int', $this->request->years());
+        $this->assertIsInt($this->request->years());
         $this->assertEquals(0, $this->request->years());
     }
 
-    public function testPurchasePrivacyProtection()
+    public function testPurchasePrivacyProtection(): void
     {
-        $this->assertInternalType('bool', $this->request->purchasePrivacyProtection());
+        $this->assertIsBool($this->request->purchasePrivacyProtection());
         $this->assertFalse($this->request->purchasePrivacyProtection());
 
         $this->request = new RenewRequest(
@@ -98,9 +98,9 @@ public function testPurchasePrivacyProtection()
         $this->assertTrue($this->request->purchasePrivacyProtection());
     }
 
-    public function testAutoRenew()
+    public function testAutoRenew(): void
     {
-        $this->assertInternalType('bool', $this->request->autoRenew());
+        $this->assertIsBool($this->request->autoRenew());
         $this->assertFalse($this->request->autoRenew());
 
         $this->request = new RenewRequest(
diff --git a/tests/unit/Orders/Domains/Responses/GetResponseTest.php b/tests/unit/Orders/Domains/Responses/GetResponseTest.php
index 69196bd..8518201 100644
--- a/tests/unit/Orders/Domains/Responses/GetResponseTest.php
+++ b/tests/unit/Orders/Domains/Responses/GetResponseTest.php
@@ -17,11 +17,11 @@
 
 class GetResponseTest extends TestCase
 {
-    public function testEntityId()
+    public function testEntityId(): void
     {
         $response = new GetResponse(['entityid' => 123]);
 
-        $this->assertInternalType('int', $response->entityId());
+        $this->assertIsInt($response->entityId());
         $this->assertEquals(123, $response->entityId());
     }
 
@@ -29,57 +29,57 @@ public function testOrderId()
     {
         $response = new GetResponse(['orderid' => 123]);
 
-        $this->assertInternalType('int', $response->orderId());
+        $this->assertIsInt($response->orderId());
         $this->assertEquals(123, $response->orderId());
 
         $response = new GetResponse(['orderid' => null]);
 
-        $this->assertInternalType('int', $response->orderId());
+        $this->assertIsInt($response->orderId());
         $this->assertEquals(0, $response->orderId());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('int', $response->orderId());
+        $this->assertIsInt($response->orderId());
         $this->assertEquals(0, $response->orderId());
     }
 
-    public function testDescription()
+    public function testDescription(): void
     {
         $response = new GetResponse(['description' => 'domain description']);
 
-        $this->assertInternalType('string', $response->description());
+        $this->assertIsString($response->description());
         $this->assertEquals('domain description', $response->description());
 
         $response = new GetResponse(['description' => null]);
 
-        $this->assertInternalType('string', $response->description());
+        $this->assertIsString($response->description());
         $this->assertEquals('', $response->description());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('string', $response->description());
+        $this->assertIsString($response->description());
         $this->assertEquals('', $response->description());
     }
 
-    public function testDomain()
+    public function testDomain(): void
     {
         $response = new GetResponse(['domainname' => 'some-domain.co.uk']);
 
-        $this->assertInternalType('string', $response->domain());
+        $this->assertIsString($response->domain());
         $this->assertEquals('some-domain.co.uk', $response->domain());
 
         $response = new GetResponse(['domainname' => null]);
 
-        $this->assertInternalType('string', $response->domain());
+        $this->assertIsString($response->domain());
         $this->assertEquals('', $response->domain());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('string', $response->domain());
+        $this->assertIsString($response->domain());
         $this->assertEquals('', $response->domain());
     }
 
-    public function testCurrentOrderStatus()
+    public function testCurrentOrderStatus(): void
     {
         $response = new GetResponse(['currentstatus' => 'Active']);
         $this->assertInstanceOf(OrderStatus::class, $response->currentOrderStatus());
@@ -91,13 +91,13 @@ public function testCurrentOrderStatus()
         $this->assertInstanceOf(OrderStatus::class, $response->currentOrderStatus());
     }
 
-    public function testRegistryStatus()
+    public function testRegistryStatus(): void
     {
         $response = new GetResponse(['orderstatus' => 'resellerlock']);
         $this->assertInstanceOf(RegistryStatus::class, $response->registryStatus());
     }
 
-    public function testLockedOrHoldStatus()
+    public function testLockedOrHoldStatus(): void
     {
         $response = new GetResponse(['domainstatus' => ['sixtydaylock']]);
         $this->assertInstanceOf(LockedOrHoldStatus::class, $response->lockedOrHoldStatus());
@@ -106,243 +106,243 @@ public function testLockedOrHoldStatus()
         $this->assertInstanceOf(LockedOrHoldStatus::class, $response->lockedOrHoldStatus());
     }
 
-    public function testProductCategory()
+    public function testProductCategory(): void
     {
         $response = new GetResponse(['productcategory' => 'domorder']);
-        $this->assertInternalType('string', $response->productCategory());
+        $this->assertIsString($response->productCategory());
         $this->assertEquals('domorder', $response->productCategory());
 
         $response = new GetResponse(['productcategory' => null]);
-        $this->assertInternalType('string', $response->productCategory());
+        $this->assertIsString($response->productCategory());
         $this->assertEquals('', $response->productCategory());
 
         $response = new GetResponse([]);
-        $this->assertInternalType('string', $response->productCategory());
+        $this->assertIsString($response->productCategory());
         $this->assertEquals('', $response->productCategory());
     }
 
-    public function testProductId()
+    public function testProductId(): void
     {
         $response = new GetResponse(['productkey' => 'dominfo']);
-        $this->assertInternalType('string', $response->productId());
+        $this->assertIsString($response->productId());
         $this->assertEquals('dominfo', $response->productId());
 
         $response = new GetResponse(['productcategory' => null]);
-        $this->assertInternalType('string', $response->productId());
+        $this->assertIsString($response->productId());
         $this->assertEquals('', $response->productId());
 
         $response = new GetResponse([]);
-        $this->assertInternalType('string', $response->productId());
+        $this->assertIsString($response->productId());
         $this->assertEquals('', $response->productId());
     }
 
-    public function testRegistryDate()
+    public function testRegistryDate(): void
     {
         $response = new GetResponse(['creationtime' => '1547570574']);
         $this->assertInstanceOf(Carbon::class, $response->registryDate());
         $this->assertEquals(Carbon::createFromTimestamp(1547570574), $response->registryDate());
     }
 
-    public function testRegistryExpiryDate()
+    public function testRegistryExpiryDate(): void
     {
         $response = new GetResponse(['endtime' => '1547570898']);
         $this->assertInstanceOf(Carbon::class, $response->registryExpiryDate());
         $this->assertEquals(Carbon::createFromTimestamp(1547570898), $response->registryExpiryDate());
     }
 
-    public function testCustomerId()
+    public function testCustomerId(): void
     {
         $response = new GetResponse(['customerid' => '17824872']);
 
-        $this->assertInternalType('int', $response->customerId());
+        $this->assertIsInt($response->customerId());
         $this->assertEquals(17824872, $response->customerId());
 
         $response = new GetResponse(['customerid' => null]);
 
-        $this->assertInternalType('int', $response->customerId());
+        $this->assertIsInt($response->customerId());
         $this->assertEquals(0, $response->customerId());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('int', $response->customerId());
+        $this->assertIsInt($response->customerId());
         $this->assertEquals(0, $response->customerId());
     }
 
-    public function testIsImmediateReseller()
+    public function testIsImmediateReseller(): void
     {
         $response = new GetResponse(['isImmediateReseller' => true]);
 
-        $this->assertInternalType('bool', $response->isImmediateReseller());
+        $this->assertIsBool($response->isImmediateReseller());
         $this->assertTrue($response->isImmediateReseller());
 
         $response = new GetResponse(['isImmediateReseller' => false]);
 
-        $this->assertInternalType('bool', $response->isImmediateReseller());
+        $this->assertIsBool($response->isImmediateReseller());
         $this->assertFalse($response->isImmediateReseller());
 
         $response = new GetResponse(['isImmediateReseller' => null]);
 
-        $this->assertInternalType('bool', $response->isImmediateReseller());
+        $this->assertIsBool($response->isImmediateReseller());
         $this->assertFalse($response->isImmediateReseller());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('bool', $response->isImmediateReseller());
+        $this->assertIsBool($response->isImmediateReseller());
         $this->assertFalse($response->isImmediateReseller());
     }
 
-    public function testResellerParentId()
+    public function testResellerParentId(): void
     {
         $response = new GetResponse(['parentkey' => '999999999_999999998_000000']);
 
-        $this->assertInternalType('string', $response->resellerParentId());
+        $this->assertIsString($response->resellerParentId());
         $this->assertEquals('999999999_999999998_000000', $response->resellerParentId());
 
         $response = new GetResponse(['parentkey' => null]);
 
-        $this->assertInternalType('string', $response->resellerParentId());
+        $this->assertIsString($response->resellerParentId());
         $this->assertEquals('', $response->resellerParentId());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('string', $response->resellerParentId());
+        $this->assertIsString($response->resellerParentId());
         $this->assertEquals('', $response->resellerParentId());
     }
 
-    public function testIsPrivacyProtectionAllowed()
+    public function testIsPrivacyProtectionAllowed(): void
     {
         $response = new GetResponse(['privacyprotectedallowed' => true]);
 
-        $this->assertInternalType('bool', $response->isPrivacyProtectionAllowed());
+        $this->assertIsBool($response->isPrivacyProtectionAllowed());
         $this->assertTrue($response->isPrivacyProtectionAllowed());
 
         $response = new GetResponse(['privacyprotectedallowed' => false]);
 
-        $this->assertInternalType('bool', $response->isPrivacyProtectionAllowed());
+        $this->assertIsBool($response->isPrivacyProtectionAllowed());
         $this->assertFalse($response->isPrivacyProtectionAllowed());
 
         $response = new GetResponse(['privacyprotectedallowed' => null]);
 
-        $this->assertInternalType('bool', $response->isPrivacyProtectionAllowed());
+        $this->assertIsBool($response->isPrivacyProtectionAllowed());
         $this->assertFalse($response->isPrivacyProtectionAllowed());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('bool', $response->isPrivacyProtectionAllowed());
+        $this->assertIsBool($response->isPrivacyProtectionAllowed());
         $this->assertFalse($response->isPrivacyProtectionAllowed());
     }
 
-    public function testIsPrivacyProtected()
+    public function testIsPrivacyProtected(): void
     {
         $response = new GetResponse(['isprivacyprotected' => true]);
 
-        $this->assertInternalType('bool', $response->isPrivacyProtected());
+        $this->assertIsBool($response->isPrivacyProtected());
         $this->assertTrue($response->isPrivacyProtected());
 
         $response = new GetResponse(['isprivacyprotected' => false]);
 
-        $this->assertInternalType('bool', $response->isPrivacyProtected());
+        $this->assertIsBool($response->isPrivacyProtected());
         $this->assertFalse($response->isPrivacyProtected());
 
         $response = new GetResponse(['isprivacyprotected' => null]);
 
-        $this->assertInternalType('bool', $response->isPrivacyProtected());
+        $this->assertIsBool($response->isPrivacyProtected());
         $this->assertFalse($response->isPrivacyProtected());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('bool', $response->isPrivacyProtected());
+        $this->assertIsBool($response->isPrivacyProtected());
         $this->assertFalse($response->isPrivacyProtected());
     }
 
-    public function testIsDeletionAllowed()
+    public function testIsDeletionAllowed(): void
     {
         $response = new GetResponse(['allowdeletion' => true]);
 
-        $this->assertInternalType('bool', $response->isDeletionAllowed());
+        $this->assertIsBool($response->isDeletionAllowed());
         $this->assertTrue($response->isDeletionAllowed());
 
         $response = new GetResponse(['allowdeletion' => false]);
 
-        $this->assertInternalType('bool', $response->isDeletionAllowed());
+        $this->assertIsBool($response->isDeletionAllowed());
         $this->assertFalse($response->isDeletionAllowed());
 
         $response = new GetResponse(['allowdeletion' => null]);
 
-        $this->assertInternalType('bool', $response->isDeletionAllowed());
+        $this->assertIsBool($response->isDeletionAllowed());
         $this->assertFalse($response->isDeletionAllowed());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('bool', $response->isDeletionAllowed());
+        $this->assertIsBool($response->isDeletionAllowed());
         $this->assertFalse($response->isDeletionAllowed());
     }
 
-    public function testIsSuspendedUponExpiry()
+    public function testIsSuspendedUponExpiry(): void
     {
         $response = new GetResponse(['isOrderSuspendedUponExpiry' => true]);
 
-        $this->assertInternalType('bool', $response->isSuspendedUponExpiry());
+        $this->assertIsBool($response->isSuspendedUponExpiry());
         $this->assertTrue($response->isSuspendedUponExpiry());
 
         $response = new GetResponse(['isOrderSuspendedUponExpiry' => false]);
 
-        $this->assertInternalType('bool', $response->isSuspendedUponExpiry());
+        $this->assertIsBool($response->isSuspendedUponExpiry());
         $this->assertFalse($response->isSuspendedUponExpiry());
 
         $response = new GetResponse(['isOrderSuspendedUponExpiry' => null]);
 
-        $this->assertInternalType('bool', $response->isSuspendedUponExpiry());
+        $this->assertIsBool($response->isSuspendedUponExpiry());
         $this->assertFalse($response->isSuspendedUponExpiry());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('bool', $response->isSuspendedUponExpiry());
+        $this->assertIsBool($response->isSuspendedUponExpiry());
         $this->assertFalse($response->isSuspendedUponExpiry());
     }
 
-    public function testIsSuspendedByParent()
+    public function testIsSuspendedByParent(): void
     {
         $response = new GetResponse(['orderSuspendedByParent' => true]);
 
-        $this->assertInternalType('bool', $response->isSuspendedByParent());
+        $this->assertIsBool($response->isSuspendedByParent());
         $this->assertTrue($response->isSuspendedByParent());
 
         $response = new GetResponse(['orderSuspendedByParent' => false]);
 
-        $this->assertInternalType('bool', $response->isSuspendedByParent());
+        $this->assertIsBool($response->isSuspendedByParent());
         $this->assertFalse($response->isSuspendedByParent());
 
         $response = new GetResponse(['orderSuspendedByParent' => null]);
 
-        $this->assertInternalType('bool', $response->isSuspendedByParent());
+        $this->assertIsBool($response->isSuspendedByParent());
         $this->assertFalse($response->isSuspendedByParent());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('bool', $response->isSuspendedByParent());
+        $this->assertIsBool($response->isSuspendedByParent());
         $this->assertFalse($response->isSuspendedByParent());
     }
 
-    public function testDomainSecret()
+    public function testDomainSecret(): void
     {
         $response = new GetResponse(['domsecret' => 'abc123']);
 
-        $this->assertInternalType('string', $response->domainSecret());
+        $this->assertIsString($response->domainSecret());
         $this->assertEquals('abc123', $response->domainSecret());
 
         $response = new GetResponse(['domsecret' => null]);
 
-        $this->assertInternalType('string', $response->domainSecret());
+        $this->assertIsString($response->domainSecret());
         $this->assertEquals('', $response->domain());
 
         $response = new GetResponse([]);
 
-        $this->assertInternalType('string', $response->domainSecret());
+        $this->assertIsString($response->domainSecret());
         $this->assertEquals('', $response->domainSecret());
     }
 
-    public function testNamedServers()
+    public function testNamedServers(): void
     {
         $response = new GetResponse([
             'noOfNameServers' => 2,
@@ -360,7 +360,7 @@ public function testNamedServers()
         $this->assertEquals('ns3.test.example.com', $response->namedServers()->childNamedServer());
     }
 
-    public function testRegistrantContact()
+    public function testRegistrantContact(): void
     {
         $response = new GetResponse([
             'registrantcontact'  => [
@@ -405,7 +405,7 @@ public function testRegistrantContact()
         $this->assertEquals('EX3 5MP', $response->registrantContact()->address()->postCode());
     }
 
-    public function testAdminContact()
+    public function testAdminContact(): void
     {
         $response = new GetResponse([
             'admincontact'  => [
@@ -450,7 +450,7 @@ public function testAdminContact()
         $this->assertEquals('EX3 5MP', $response->adminContact()->address()->postCode());
     }
 
-    public function testTechnicalContact()
+    public function testTechnicalContact(): void
     {
         $response = new GetResponse([
             'techcontact'  => [
@@ -495,7 +495,7 @@ public function testTechnicalContact()
         $this->assertEquals('EX3 5MP', $response->technicalContact()->address()->postCode());
     }
 
-    public function testBillingContact()
+    public function testBillingContact(): void
     {
         $response = new GetResponse([
             'billingcontact'  => [
@@ -540,7 +540,7 @@ public function testBillingContact()
         $this->assertEquals('EX3 5MP', $response->billingContact()->address()->postCode());
     }
 
-    public function testGdprProtection()
+    public function testGdprProtection(): void
     {
         $response = new GetResponse([
             'gdpr' => [
@@ -554,7 +554,7 @@ public function testGdprProtection()
         $this->assertFalse($response->gdprProtection()->eligible());
     }
 
-    public function testRegistrantContactVerification()
+    public function testRegistrantContactVerification(): void
     {
         $response = new GetResponse([
             'raaVerificationStatus'    => 'Pending',
@@ -569,7 +569,7 @@ public function testRegistrantContactVerification()
         );
     }
 
-    public function testPrivacyProtection()
+    public function testPrivacyProtection(): void
     {
         $response = new GetResponse([
             'privacyprotectendtime'     => '1547565748',
@@ -585,7 +585,7 @@ public function testPrivacyProtection()
         $this->assertEquals('billing', $response->privacyProtection()->billingContact());
     }
 
-    public function testDelegationSigner()
+    public function testDelegationSigner(): void
     {
         $response = new GetResponse([
             'dnssec' => [
@@ -603,13 +603,13 @@ public function testDelegationSigner()
         $this->assertEquals('SHA-256', $response->delegationSigner()->digestType());
     }
 
-    public function testRecurring()
+    public function testRecurring(): void
     {
         $response = new GetResponse([
             'recurring' => true,
         ]);
 
-        $this->assertInternalType('bool', $response->recurring());
+        $this->assertIsBool($response->recurring());
         $this->assertTrue($response->recurring());
 
         $response = new GetResponse([
@@ -621,84 +621,84 @@ public function testRecurring()
         $this->assertFalse($response->recurring());
     }
 
-    public function testCustomerCost()
+    public function testCustomerCost(): void
     {
         $response = new GetResponse(['customercost' => '0.0']);
 
-        $this->assertInternalType('float', $response->customerCost());
+        $this->assertIsFloat($response->customerCost());
         $this->assertEquals('0.00', $response->customerCost());
     }
 
-    public function testMoneyBackPeriod()
+    public function testMoneyBackPeriod(): void
     {
         $response = new GetResponse(['moneybackperiod' => 30]);
 
-        $this->assertInternalType('int', $response->moneyBackPeriod());
+        $this->assertIsInt($response->moneyBackPeriod());
         $this->assertEquals(30, $response->moneyBackPeriod());
     }
 
-    public function testResellerCost()
+    public function testResellerCost(): void
     {
         $response = new GetResponse(['resellercost' => '0.0']);
 
-        $this->assertInternalType('float', $response->resellerCost());
+        $this->assertIsFloat($response->resellerCost());
         $this->assertEquals('0.00', $response->resellerCost());
     }
 
-    public function testJumpConditions()
+    public function testJumpConditions(): void
     {
         $response = new GetResponse(['jumpConditions' => []]);
-        $this->assertInternalType('array', $response->jumpConditions());
+        $this->assertIsArray($response->jumpConditions());
     }
 
-    public function testPaused()
+    public function testPaused(): void
     {
         $response = new GetResponse(['paused' => true]);
-        $this->assertInternalType('bool', $response->paused());
+        $this->assertIsBool($response->paused());
         $this->assertTrue($response->paused());
 
         $response = new GetResponse(['paused' => false]);
-        $this->assertInternalType('bool', $response->paused());
+        $this->assertIsBool($response->paused());
         $this->assertFalse($response->paused());
     }
 
-    public function testEaqId()
+    public function testEaqId(): void
     {
         $response = new GetResponse(['eaqid' => 0]);
 
-        $this->assertInternalType('int', $response->eaqId());
+        $this->assertIsInt($response->eaqId());
         $this->assertEquals(0, $response->eaqId());
     }
 
-    public function testEntityTypeId()
+    public function testEntityTypeId(): void
     {
         $response = new GetResponse(['entitytypeid' => 283]);
 
-        $this->assertInternalType('int', $response->entityTypeId());
+        $this->assertIsInt($response->entityTypeId());
         $this->assertEquals(283, $response->entityTypeId());
     }
 
-    public function testActionCompleted()
+    public function testActionCompleted(): void
     {
         $response = new GetResponse(['actioncompleted' => '0']);
 
-        $this->assertInternalType('string', $response->actionCompleted());
+        $this->assertIsString($response->actionCompleted());
         $this->assertEquals('0', $response->actionCompleted());
     }
 
-    public function testAutoRenewAttemptDuration()
+    public function testAutoRenewAttemptDuration(): void
     {
         $response = new GetResponse(['actioncompleted' => '0']);
 
-        $this->assertInternalType('integer', $response->autoRenewAttemptDuration());
+        $this->assertIsInt($response->autoRenewAttemptDuration());
         $this->assertEquals('0', $response->autoRenewAttemptDuration());
     }
 
-    public function testAutoRenewTermType()
+    public function testAutoRenewTermType(): void
     {
         $response = new GetResponse(['autoRenewTermType' => 'LONG_TERM']);
 
-        $this->assertInternalType('string', $response->autoRenewTermType());
+        $this->assertIsString($response->autoRenewTermType());
         $this->assertEquals('LONG_TERM', $response->autoRenewTermType());
     }
 }
diff --git a/tests/unit/Orders/Domains/Responses/PrivacyProtectionOrderResponseTest.php b/tests/unit/Orders/Domains/Responses/PrivacyProtectionOrderResponseTest.php
index 8e89967..dcfa404 100644
--- a/tests/unit/Orders/Domains/Responses/PrivacyProtectionOrderResponseTest.php
+++ b/tests/unit/Orders/Domains/Responses/PrivacyProtectionOrderResponseTest.php
@@ -17,7 +17,7 @@ class PrivacyProtectionOrderResponseTest extends TestCase
      */
     private $response;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -38,7 +38,7 @@ protected function setUp()
         ]);
     }
 
-    public function testFeatureNotAvailableExceptionThrown()
+    public function testFeatureNotAvailableExceptionThrown(): void
     {
         $this->expectException(FeatureNotAvailableException::class);
 
@@ -49,17 +49,17 @@ public function testFeatureNotAvailableExceptionThrown()
         ]);
     }
 
-    public function testItCanOrderId()
+    public function testItCanOrderId(): void
     {
         $this->assertEquals(85575828, $this->response->orderId());
     }
 
-    public function testItCanGetDescription()
+    public function testItCanGetDescription(): void
     {
         $this->assertEquals('wibble-wibble.net', $this->response->description());
     }
 
-    public function testItCanGetAction()
+    public function testItCanGetAction(): void
     {
         $action = $this->response->action();
         $this->assertInstanceOf(Action::class, $action);
@@ -73,34 +73,34 @@ public function testItCanGetAction()
         $this->assertEquals('Operation completed successfully', $action->statusDescription());
     }
 
-    public function testItCanGetInvoiceId()
+    public function testItCanGetInvoiceId(): void
     {
         $this->assertEquals(88768089, $this->response->invoiceId());
     }
 
-    public function testItCanGetSellingCurrencySymbol()
+    public function testItCanGetSellingCurrencySymbol(): void
     {
         $this->assertEquals('GBP', $this->response->sellingCurrencySymbol());
     }
 
-    public function testItCanGetSellingCurrency()
+    public function testItCanGetSellingCurrency(): void
     {
         $this->assertInstanceOf(Currency::class, $this->response->sellingCurrency());
     }
 
-    public function testItCanGetSellingAmount()
+    public function testItCanGetSellingAmount(): void
     {
         $this->assertInstanceOf(Money::class, $this->response->sellingAmount());
         $this->assertEquals(0, $this->response->sellingAmount()->getAmount());
     }
 
-    public function testItCanGetUnutilisedSellingAmount()
+    public function testItCanGetUnutilisedSellingAmount(): void
     {
         $this->assertInstanceOf(Money::class, $this->response->unutilisedSellingAmount());
         $this->assertEquals(0, $this->response->unutilisedSellingAmount()->getAmount());
     }
 
-    public function testItCanGetCustomerId()
+    public function testItCanGetCustomerId(): void
     {
         $this->assertEquals(17824872, $this->response->customerId());
     }
diff --git a/tests/unit/Orders/Domains/Responses/RenewalResponseTest.php b/tests/unit/Orders/Domains/Responses/RenewalResponseTest.php
index 6eb64d8..3eb0d11 100644
--- a/tests/unit/Orders/Domains/Responses/RenewalResponseTest.php
+++ b/tests/unit/Orders/Domains/Responses/RenewalResponseTest.php
@@ -17,7 +17,7 @@ class RenewalResponseTest extends TestCase
      */
     private $response;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -43,17 +43,17 @@ protected function setUp()
         ]);
     }
 
-    public function testItCanOrderId()
+    public function testItCanOrderId(): void
     {
         $this->assertEquals(85547813, $this->response->orderId());
     }
 
-    public function testItCanGetDescription()
+    public function testItCanGetDescription(): void
     {
         $this->assertEquals('yesterday.co.in', $this->response->description());
     }
 
-    public function testItCanGetAction()
+    public function testItCanGetAction(): void
     {
         $action = $this->response->action();
         $this->assertInstanceOf(Action::class, $action);
@@ -64,39 +64,39 @@ public function testItCanGetAction()
         $this->assertEquals('Domain renewed successfully', $action->statusDescription());
     }
 
-    public function testItCanGetInvoiceId()
+    public function testItCanGetInvoiceId(): void
     {
         $this->assertEquals(88713188, $this->response->invoiceId());
     }
 
-    public function testItCanGetSellingCurrencySymbol()
+    public function testItCanGetSellingCurrencySymbol(): void
     {
         $this->assertEquals('GBP', $this->response->sellingCurrencySymbol());
     }
 
-    public function testItCanGetSellingCurrency()
+    public function testItCanGetSellingCurrency(): void
     {
         $this->assertInstanceOf(Currency::class, $this->response->sellingCurrency());
     }
 
-    public function testItCanGetSellingAmount()
+    public function testItCanGetSellingAmount(): void
     {
         $this->assertInstanceOf(Money::class, $this->response->sellingAmount());
         $this->assertEquals(-791, $this->response->sellingAmount()->getAmount());
     }
 
-    public function testItCanGetUnutilisedSellingAmount()
+    public function testItCanGetUnutilisedSellingAmount(): void
     {
         $this->assertInstanceOf(Money::class, $this->response->unutilisedSellingAmount());
         $this->assertEquals(-791, $this->response->unutilisedSellingAmount()->getAmount());
     }
 
-    public function testItCanGetCustomerId()
+    public function testItCanGetCustomerId(): void
     {
         $this->assertEquals(17824872, $this->response->customerId());
     }
 
-    public function testItCanGetPrivacyProtectionDetails()
+    public function testItCanGetPrivacyProtectionDetails(): void
     {
         $response = new RenewalResponse([
             'privacydetails'          => [
diff --git a/tests/unit/Orders/EmailAccounts/EmailAccountTest.php b/tests/unit/Orders/EmailAccounts/EmailAccountTest.php
index 4be74b9..d715545 100644
--- a/tests/unit/Orders/EmailAccounts/EmailAccountTest.php
+++ b/tests/unit/Orders/EmailAccounts/EmailAccountTest.php
@@ -19,7 +19,7 @@
 
 class EmailAccountTest extends TestCase
 {
-    public function testResponseFromEmailAccountDelete()
+    public function testResponseFromEmailAccountDelete(): void
     {
         $mock = new MockHandler([
             new Response(
@@ -46,7 +46,7 @@ public function testResponseFromEmailAccountDelete()
         );
     }
 
-    public function testResponseFromEmailAccountCreate()
+    public function testResponseFromEmailAccountCreate(): void
     {
         $mock = new MockHandler([
             new Response(
diff --git a/tests/unit/Orders/EmailAccounts/Requests/CreateRequestTest.php b/tests/unit/Orders/EmailAccounts/Requests/CreateRequestTest.php
index fdbe8b2..045f586 100644
--- a/tests/unit/Orders/EmailAccounts/Requests/CreateRequestTest.php
+++ b/tests/unit/Orders/EmailAccounts/Requests/CreateRequestTest.php
@@ -14,7 +14,7 @@ class CreateRequestTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -33,44 +33,44 @@ protected function setUp()
         );
     }
 
-    public function testOrderId()
+    public function testOrderId(): void
     {
         $this->assertEquals(123, $this->request->orderId());
     }
 
-    public function testEmail()
+    public function testEmail(): void
     {
         $this->assertInstanceOf(EmailAddress::class, $this->request->email());
         $this->assertEquals('john.doe@my-domain.co.uk', (string) $this->request->email());
     }
 
-    public function testPassword()
+    public function testPassword(): void
     {
         $this->assertEquals('myT35tP@55word', $this->request->password());
     }
 
-    public function testNotificationEmail()
+    public function testNotificationEmail(): void
     {
         $this->assertInstanceOf(EmailAddress::class, $this->request->notificationEmail());
         $this->assertEquals('alternative@test.com', (string) $this->request->notificationEmail());
     }
 
-    public function testFirstName()
+    public function testFirstName(): void
     {
         $this->assertEquals('John', $this->request->firstName());
     }
 
-    public function testLastName()
+    public function testLastName(): void
     {
         $this->assertEquals('Doe', $this->request->lastName());
     }
 
-    public function testCountryCode()
+    public function testCountryCode(): void
     {
         $this->assertEquals('US', $this->request->countryCode());
     }
 
-    public function testLanguageCode()
+    public function testLanguageCode(): void
     {
         $this->assertEquals('en', $this->request->languageCode());
     }
diff --git a/tests/unit/Orders/EmailAccounts/Requests/DeleteRequestTest.php b/tests/unit/Orders/EmailAccounts/Requests/DeleteRequestTest.php
index feca88f..fad90f2 100644
--- a/tests/unit/Orders/EmailAccounts/Requests/DeleteRequestTest.php
+++ b/tests/unit/Orders/EmailAccounts/Requests/DeleteRequestTest.php
@@ -14,7 +14,7 @@ class DeleteRequestTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -26,12 +26,12 @@ protected function setUp()
         );
     }
 
-    public function testOrderId()
+    public function testOrderId(): void
     {
         $this->assertEquals(123, $this->request->orderId());
     }
 
-    public function testEmail()
+    public function testEmail(): void
     {
         $this->assertEquals('john.doe@my-domain.co.uk', $this->request->email());
     }
diff --git a/tests/unit/Orders/EmailAccounts/Responses/CreateResponseTest.php b/tests/unit/Orders/EmailAccounts/Responses/CreateResponseTest.php
index fbaa20a..56f2e6d 100644
--- a/tests/unit/Orders/EmailAccounts/Responses/CreateResponseTest.php
+++ b/tests/unit/Orders/EmailAccounts/Responses/CreateResponseTest.php
@@ -16,7 +16,7 @@
 
 class CreateResponseTest extends TestCase
 {
-    public function testResponseExceptionThrownWhenValidationErrorIsReturn()
+    public function testResponseExceptionThrownWhenValidationErrorIsReturn(): void
     {
         try {
             new CreateResponse(['response' => [
@@ -33,7 +33,7 @@ public function testResponseExceptionThrownWhenValidationErrorIsReturn()
         $this->fail('The missing attribute exception was not thrown for the user.');
     }
 
-    public function testMissingAttributeExceptionThrownWhenUserNotSetInResponse()
+    public function testMissingAttributeExceptionThrownWhenUserNotSetInResponse(): void
     {
         try {
             new CreateResponse([
@@ -50,7 +50,7 @@ public function testMissingAttributeExceptionThrownWhenUserNotSetInResponse()
         $this->fail('The missing attribute exception was not thrown for the user.');
     }
 
-    public function testStatus()
+    public function testStatus(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -63,7 +63,7 @@ public function testStatus()
         $this->assertEquals('success', (string) $response->status());
     }
 
-    public function testStatusNotSetInResponse()
+    public function testStatusNotSetInResponse(): void
     {
         try {
             $response = new CreateResponse([
@@ -81,7 +81,7 @@ public function testStatusNotSetInResponse()
         $this->fail('The missing attribute exception was not thrown for the status.');
     }
 
-    public function testEmail()
+    public function testEmail(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -96,7 +96,7 @@ public function testEmail()
         $this->assertEquals('john.does@some-domain.co.uk', (string) $response->email());
     }
 
-    public function testDomain()
+    public function testDomain(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -107,11 +107,11 @@ public function testDomain()
             ],
         ]);
 
-        $this->assertInternalType('string', $response->domain());
+        $this->assertIsString($response->domain());
         $this->assertEquals('some-domain.co.uk', $response->domain());
     }
 
-    public function testFirstName()
+    public function testFirstName(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -122,11 +122,11 @@ public function testFirstName()
             ],
         ]);
 
-        $this->assertInternalType('string', $response->firstName());
+        $this->assertIsString($response->firstName());
         $this->assertEquals('John', $response->firstName());
     }
 
-    public function testLastName()
+    public function testLastName(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -137,11 +137,11 @@ public function testLastName()
             ],
         ]);
 
-        $this->assertInternalType('string', $response->lastName());
+        $this->assertIsString($response->lastName());
         $this->assertEquals('Doe', $response->lastName());
     }
 
-    public function testNotificationsEmail()
+    public function testNotificationsEmail(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -156,7 +156,7 @@ public function testNotificationsEmail()
         $this->assertEquals('another-email@some-domain.co.uk', (string) $response->notificationsEmail());
     }
 
-    public function testInternalForwards()
+    public function testInternalForwards(): void
     {
         $expected_result = 'new:somedomain.co.in.onlyfordemo.com@set25.mss.mailhostbox.aus-tx.colo';
 
@@ -169,11 +169,11 @@ public function testInternalForwards()
             ],
         ]);
 
-        $this->assertInternalType('string', $response->internalForwards());
+        $this->assertIsString($response->internalForwards());
         $this->assertEquals($expected_result, $response->internalForwards());
     }
 
-    public function testQuotaLimit()
+    public function testQuotaLimit(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -184,11 +184,11 @@ public function testQuotaLimit()
             ],
         ]);
 
-        $this->assertInternalType('int', $response->quotaLimit());
+        $this->assertIsInt($response->quotaLimit());
         $this->assertEquals(5242880, $response->quotaLimit());
     }
 
-    public function testAccountStatus()
+    public function testAccountStatus(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -199,11 +199,11 @@ public function testAccountStatus()
             ],
         ]);
 
-        $this->assertInternalType('string', $response->accountStatus());
+        $this->assertIsString($response->accountStatus());
         $this->assertEquals('active', $response->accountStatus());
     }
 
-    public function testAccountType()
+    public function testAccountType(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -214,11 +214,11 @@ public function testAccountType()
             ],
         ]);
 
-        $this->assertInternalType('string', $response->accountType());
+        $this->assertIsString($response->accountType());
         $this->assertEquals('POP_WITHOUT_AUTORESPONDER', $response->accountType());
     }
 
-    public function testQuotaUsed()
+    public function testQuotaUsed(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -229,11 +229,11 @@ public function testQuotaUsed()
             ],
         ]);
 
-        $this->assertInternalType('int', $response->quotaUsed());
+        $this->assertIsInt($response->quotaUsed());
         $this->assertEquals(0, $response->quotaUsed());
     }
 
-    public function testCountryCode()
+    public function testCountryCode(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -244,11 +244,11 @@ public function testCountryCode()
             ],
         ]);
 
-        $this->assertInternalType('string', $response->countryCode());
+        $this->assertIsString($response->countryCode());
         $this->assertEquals('US', $response->countryCode());
     }
 
-    public function testPercentageQuotaUsage()
+    public function testPercentageQuotaUsage(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -259,11 +259,11 @@ public function testPercentageQuotaUsage()
             ],
         ]);
 
-        $this->assertInternalType('float', $response->percentageQuotaUsage());
+        $this->assertIsFloat($response->percentageQuotaUsage());
         $this->assertEquals(0, $response->percentageQuotaUsage());
     }
 
-    public function testLanguageCode()
+    public function testLanguageCode(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -274,11 +274,11 @@ public function testLanguageCode()
             ],
         ]);
 
-        $this->assertInternalType('string', $response->languageCode());
+        $this->assertIsString($response->languageCode());
         $this->assertEquals('en', $response->languageCode());
     }
 
-    public function testAccountSettings()
+    public function testAccountSettings(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -296,7 +296,7 @@ public function testAccountSettings()
 
         $accountSettings = $response->accountSettings();
 
-        $this->assertInternalType('array', $accountSettings);
+        $this->assertIsArray($accountSettings);
         $this->assertCount(4, $accountSettings);
 
         $this->assertArrayHasKey('pop', $accountSettings);
@@ -310,7 +310,7 @@ public function testAccountSettings()
         $this->assertInstanceOf(WebmailUrlSettings::class, $accountSettings['webmail']);
     }
 
-    public function testCreatedOn()
+    public function testCreatedOn(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -325,7 +325,7 @@ public function testCreatedOn()
         $this->assertEquals('2017-11-10 17:45:17', $response->createdOn()->format('Y-m-d H:i:s'));
     }
 
-    public function testPopAccessEnabled()
+    public function testPopAccessEnabled(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -336,11 +336,11 @@ public function testPopAccessEnabled()
             ],
         ]);
 
-        $this->assertInternalType('bool', $response->popAccessEnabled());
+        $this->assertIsBool($response->popAccessEnabled());
         $this->assertTrue($response->popAccessEnabled());
     }
 
-    public function testImapAccessEnabled()
+    public function testImapAccessEnabled(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -351,11 +351,11 @@ public function testImapAccessEnabled()
             ],
         ]);
 
-        $this->assertInternalType('bool', $response->imapAccessEnabled());
+        $this->assertIsBool($response->imapAccessEnabled());
         $this->assertTrue($response->imapAccessEnabled());
     }
 
-    public function testWebmailAccessEnabled()
+    public function testWebmailAccessEnabled(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -366,11 +366,11 @@ public function testWebmailAccessEnabled()
             ],
         ]);
 
-        $this->assertInternalType('bool', $response->webmailAccessEnabled());
+        $this->assertIsBool($response->webmailAccessEnabled());
         $this->assertTrue($response->webmailAccessEnabled());
     }
 
-    public function testCanFooterOptout()
+    public function testCanFooterOptout(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -381,11 +381,11 @@ public function testCanFooterOptout()
             ],
         ]);
 
-        $this->assertInternalType('bool', $response->canFooterOptout());
+        $this->assertIsBool($response->canFooterOptout());
         $this->assertFalse($response->canFooterOptout());
     }
 
-    public function testRevertBlacklistRequestExists()
+    public function testRevertBlacklistRequestExists(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -396,11 +396,11 @@ public function testRevertBlacklistRequestExists()
             ],
         ]);
 
-        $this->assertInternalType('bool', $response->revertBlacklistRequestExists());
+        $this->assertIsBool($response->revertBlacklistRequestExists());
         $this->assertFalse($response->revertBlacklistRequestExists());
     }
 
-    public function testConfigurationProfile()
+    public function testConfigurationProfile(): void
     {
         $response = new CreateResponse([
             'response' => [
@@ -411,7 +411,7 @@ public function testConfigurationProfile()
             ],
         ]);
 
-        $this->assertInternalType('string', $response->configurationProfile());
+        $this->assertIsString($response->configurationProfile());
         $this->assertEquals('EELITE', $response->configurationProfile());
     }
 }
diff --git a/tests/unit/Orders/EmailAccounts/Responses/DeletedResponseTest.php b/tests/unit/Orders/EmailAccounts/Responses/DeletedResponseTest.php
index 81bc5d0..e207ac7 100644
--- a/tests/unit/Orders/EmailAccounts/Responses/DeletedResponseTest.php
+++ b/tests/unit/Orders/EmailAccounts/Responses/DeletedResponseTest.php
@@ -11,7 +11,7 @@
 
 class DeletedResponseTest extends TestCase
 {
-    public function testMissingAttributeExceptionThrownWhenStatusNotSetInResponse()
+    public function testMissingAttributeExceptionThrownWhenStatusNotSetInResponse(): void
     {
         try {
             new DeletedResponse(['response' => []]);
@@ -24,7 +24,7 @@ public function testMissingAttributeExceptionThrownWhenStatusNotSetInResponse()
         $this->fail('The missing attribute exception has not been thrown.');
     }
 
-    public function testStatusSet()
+    public function testStatusSet(): void
     {
         $response = new DeletedResponse([
             'response' => ['status' => 'SUCCESS'],
@@ -34,7 +34,7 @@ public function testStatusSet()
         $this->assertEquals('success', (string) $response->status());
     }
 
-    public function testDoesNotExistResponseThrownWhenEmailAddressErrorCodeFound()
+    public function testDoesNotExistResponseThrownWhenEmailAddressErrorCodeFound(): void
     {
         $this->expectException(DoesNotExistResponseException::class);
         new DeletedResponse([
@@ -46,7 +46,7 @@ public function testDoesNotExistResponseThrownWhenEmailAddressErrorCodeFound()
         ]);
     }
 
-    public function testResponseExceptionThrownWhenNotSuccessful()
+    public function testResponseExceptionThrownWhenNotSuccessful(): void
     {
         try {
             new DeletedResponse([
diff --git a/tests/unit/Orders/EmailAccounts/Settings/ImapSettingsTest.php b/tests/unit/Orders/EmailAccounts/Settings/ImapSettingsTest.php
index 21a470a..ab1865b 100644
--- a/tests/unit/Orders/EmailAccounts/Settings/ImapSettingsTest.php
+++ b/tests/unit/Orders/EmailAccounts/Settings/ImapSettingsTest.php
@@ -7,7 +7,7 @@
 
 class ImapSettingsTest extends TestCase
 {
-    public function testImapSettings()
+    public function testImapSettings(): void
     {
         $imapSettings = new ImapSettings('imap.somedomain.co.in.onlyfordemo.com');
 
diff --git a/tests/unit/Orders/EmailAccounts/Settings/PopSettingsTest.php b/tests/unit/Orders/EmailAccounts/Settings/PopSettingsTest.php
index 2c3c4f1..c628133 100644
--- a/tests/unit/Orders/EmailAccounts/Settings/PopSettingsTest.php
+++ b/tests/unit/Orders/EmailAccounts/Settings/PopSettingsTest.php
@@ -7,7 +7,7 @@
 
 class PopSettingsTest extends TestCase
 {
-    public function testPopSettings()
+    public function testPopSettings(): void
     {
         $popSettings = new PopSettings('pop.somedomain.co.in.onlyfordemo.com');
 
diff --git a/tests/unit/Orders/EmailAccounts/Settings/SmtpSettingsTest.php b/tests/unit/Orders/EmailAccounts/Settings/SmtpSettingsTest.php
index f78d31a..6e46be1 100644
--- a/tests/unit/Orders/EmailAccounts/Settings/SmtpSettingsTest.php
+++ b/tests/unit/Orders/EmailAccounts/Settings/SmtpSettingsTest.php
@@ -7,7 +7,7 @@
 
 class SmtpSettingsTest extends TestCase
 {
-    public function testImapSettings()
+    public function testImapSettings(): void
     {
         $smtpSettings = new SmtpSettings('smtp.somedomain.co.in.onlyfordemo.com');
 
diff --git a/tests/unit/Orders/EmailAccounts/Settings/WebmailUrlSettingsTest.php b/tests/unit/Orders/EmailAccounts/Settings/WebmailUrlSettingsTest.php
index 56caff8..826bc64 100644
--- a/tests/unit/Orders/EmailAccounts/Settings/WebmailUrlSettingsTest.php
+++ b/tests/unit/Orders/EmailAccounts/Settings/WebmailUrlSettingsTest.php
@@ -7,7 +7,7 @@
 
 class WebmailUrlSettingsTest extends TestCase
 {
-    public function testWebmailUrlSettings()
+    public function testWebmailUrlSettings(): void
     {
         $webmailUrlSettings = new WebmailUrlSettings('http://webmail.somedomain.co.in.onlyfordemo.com');
 
diff --git a/tests/unit/Orders/EmailForwarders/EmailForwarderTest.php b/tests/unit/Orders/EmailForwarders/EmailForwarderTest.php
index f8eb31b..ed8dea6 100644
--- a/tests/unit/Orders/EmailForwarders/EmailForwarderTest.php
+++ b/tests/unit/Orders/EmailForwarders/EmailForwarderTest.php
@@ -17,7 +17,7 @@
 
 class EmailForwarderTest extends TestCase
 {
-    public function testResponseFromEmailForwarderDelete()
+    public function testResponseFromEmailForwarderDelete(): void
     {
         $mock = new MockHandler([
             new Response(
diff --git a/tests/unit/Orders/EmailForwarders/Requests/CreateRequestTest.php b/tests/unit/Orders/EmailForwarders/Requests/CreateRequestTest.php
index f9667b6..3e1a243 100644
--- a/tests/unit/Orders/EmailForwarders/Requests/CreateRequestTest.php
+++ b/tests/unit/Orders/EmailForwarders/Requests/CreateRequestTest.php
@@ -14,7 +14,7 @@ class CreateRequestTest extends TestCase
      */
     private $request;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -28,9 +28,9 @@ protected function setUp()
         ]);
     }
 
-    public function testItCanGetOrderId()
+    public function testItCanGetOrderId(): void
     {
-        $this->assertInternalType('integer', $this->request->orderId());
+        $this->assertIsInt($this->request->orderId());
         $this->assertEquals(123, $this->request->orderId());
     }
 
@@ -41,7 +41,7 @@ public function testItCanGetEmail()
 
     public function testItCanGetForwarders()
     {
-        $this->assertInternalType('string', $this->request->forwarders());
+        $this->assertIsString($this->request->forwarders());
         $this->assertEquals(
             'john.doe@example.com,jane.doe@example.com',
             $this->request->forwarders()
diff --git a/tests/unit/Orders/EmailForwarders/Responses/CreateResponseTest.php b/tests/unit/Orders/EmailForwarders/Responses/CreateResponseTest.php
index bf0d654..0079d31 100644
--- a/tests/unit/Orders/EmailForwarders/Responses/CreateResponseTest.php
+++ b/tests/unit/Orders/EmailForwarders/Responses/CreateResponseTest.php
@@ -13,7 +13,7 @@ class CreateResponseTest extends TestCase
      */
     private $response;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         parent::setUp();
 
@@ -24,7 +24,7 @@ protected function setUp()
         ]);
     }
 
-    public function testItCanGetStatus()
+    public function testItCanGetStatus(): void
     {
         $this->assertInstanceOf(Status::class, $this->response->status());
         $this->assertEquals('success', (string) $this->response->status());
diff --git a/tests/unit/Orders/GdprProtectionTest.php b/tests/unit/Orders/GdprProtectionTest.php
index f201003..2feac21 100644
--- a/tests/unit/Orders/GdprProtectionTest.php
+++ b/tests/unit/Orders/GdprProtectionTest.php
@@ -7,7 +7,7 @@
 
 class GdprProtectionTest extends TestCase
 {
-    public function testEnabledAndDisabled()
+    public function testEnabledAndDisabled(): void
     {
         $this->assertTrue(
             (new GdprProtection(
@@ -38,7 +38,7 @@ public function testEnabledAndDisabled()
         );
     }
 
-    public function testEligibility()
+    public function testEligibility(): void
     {
         $this->assertTrue(
             (new GdprProtection(
diff --git a/tests/unit/Orders/InvoiceOptionTest.php b/tests/unit/Orders/InvoiceOptionTest.php
index 05e7d7c..08de63c 100644
--- a/tests/unit/Orders/InvoiceOptionTest.php
+++ b/tests/unit/Orders/InvoiceOptionTest.php
@@ -7,7 +7,7 @@
 
 class InvoiceOptionTest extends TestCase
 {
-    public function testValidStatuses()
+    public function testValidStatuses(): void
     {
         $this->assertEquals('NoInvoice', (string) InvoiceOption::noInvoice());
         $this->assertEquals('PayInvoice', (string) InvoiceOption::payInvoice());
diff --git a/tests/unit/Orders/LockedOrHoldStatusTest.php b/tests/unit/Orders/LockedOrHoldStatusTest.php
index c18e9e4..1a7e81d 100644
--- a/tests/unit/Orders/LockedOrHoldStatusTest.php
+++ b/tests/unit/Orders/LockedOrHoldStatusTest.php
@@ -7,25 +7,25 @@
 
 class LockedOrHoldStatusTest extends TestCase
 {
-    public function testObjectToString()
+    public function testObjectToString(): void
     {
         $this->assertEquals('sixtydaylock', (string) new LockedOrHoldStatus('sixtydaylock'));
         $this->assertEquals('', (string) new LockedOrHoldStatus(''));
     }
 
-    public function testIsLocked()
+    public function testIsLocked(): void
     {
         $this->assertTrue((new LockedOrHoldStatus('sixtydaylock'))->isLocked());
         $this->assertFalse((new LockedOrHoldStatus('not_locked_status'))->isLocked());
     }
 
-    public function testIsOnHold()
+    public function testIsOnHold(): void
     {
         $this->assertTrue((new LockedOrHoldStatus('renewhold'))->isOnHold());
         $this->assertFalse((new LockedOrHoldStatus('not_on_hold_status'))->isOnHold());
     }
 
-    public function testIsLockedOrOnHold()
+    public function testIsLockedOrOnHold(): void
     {
         $this->assertTrue((new LockedOrHoldStatus('sixtydaylock'))->isLockedOrOnHold());
         $this->assertTrue((new LockedOrHoldStatus('renewhold'))->isLockedOrOnHold());
diff --git a/tests/unit/Orders/OrderStatusTest.php b/tests/unit/Orders/OrderStatusTest.php
index e7e7641..137e166 100644
--- a/tests/unit/Orders/OrderStatusTest.php
+++ b/tests/unit/Orders/OrderStatusTest.php
@@ -7,38 +7,38 @@
 
 class OrderStatusTest extends TestCase
 {
-    public function testToStringConvertsToLowercase()
+    public function testToStringConvertsToLowercase(): void
     {
         $this->assertEquals('active', (string) new OrderStatus('Active'));
         $this->assertEquals('active', (string) new OrderStatus('active'));
         $this->assertEquals('active', (string) new OrderStatus('ACTIVE'));
     }
 
-    public function testIsActive()
+    public function testIsActive(): void
     {
         $this->assertTrue((new OrderStatus('Active'))->isActive());
         $this->assertFalse((new OrderStatus('Not active'))->isActive());
     }
 
-    public function testIsInactive()
+    public function testIsInactive(): void
     {
         $this->assertTrue((new OrderStatus('inactive'))->isInactive());
         $this->assertFalse((new OrderStatus('active'))->isInactive());
     }
 
-    public function testIsPendingDeletion()
+    public function testIsPendingDeletion(): void
     {
         $this->assertTrue((new OrderStatus('pending delete restorable'))->isPendingDeletion());
         $this->assertFalse((new OrderStatus('active'))->isPendingDeletion());
     }
 
-    public function testIsDeleted()
+    public function testIsDeleted(): void
     {
         $this->assertTrue((new OrderStatus('Deleted'))->isDeleted());
         $this->assertFalse((new OrderStatus('active'))->isDeleted());
     }
 
-    public function testIsArchived()
+    public function testIsArchived(): void
     {
         $this->assertTrue((new OrderStatus('archived'))->isArchived());
         $this->assertFalse((new OrderStatus('active'))->isArchived());
diff --git a/tests/unit/Orders/OrderTest.php b/tests/unit/Orders/OrderTest.php
index 259f3df..4b0d7e7 100644
--- a/tests/unit/Orders/OrderTest.php
+++ b/tests/unit/Orders/OrderTest.php
@@ -7,11 +7,11 @@
 
 class OrderTest extends TestCase
 {
-    public function testGettingIdWhenSet()
+    public function testGettingIdWhenSet(): void
     {
         $orderId = (new Order(123))->id();
 
-        $this->assertInternalType('int', $orderId);
+        $this->assertIsInt($orderId);
         $this->assertEquals(123, $orderId);
     }
 }
diff --git a/tests/unit/ResponseTest.php b/tests/unit/ResponseTest.php
index f6f5eb1..59674ec 100644
--- a/tests/unit/ResponseTest.php
+++ b/tests/unit/ResponseTest.php
@@ -13,7 +13,7 @@
 
 class ResponseTest extends TestCase
 {
-    public function testStatus()
+    public function testStatus(): void
     {
         $response = new Response(
             200,
@@ -28,7 +28,7 @@ public function testStatus()
         $this->assertEquals('success', CreateResponse::fromApiResponse($response)->status());
     }
 
-    public function testMessage()
+    public function testMessage(): void
     {
         $message = 'The request executed successfully';
         $response = new Response(
@@ -44,7 +44,7 @@ public function testMessage()
         $this->assertEquals($message, UpdateResponse::fromApiResponse($response)->message());
     }
 
-    public function wasSuccessful()
+    public function wasSuccessful(): void
     {
         $successfulResponse = new Response(
             200,
diff --git a/tests/unit/StatusTest.php b/tests/unit/StatusTest.php
index 4b7b6ea..83f8938 100644
--- a/tests/unit/StatusTest.php
+++ b/tests/unit/StatusTest.php
@@ -7,7 +7,7 @@
 
 class StatusTest extends TestCase
 {
-    public function testStatus()
+    public function testStatus(): void
     {
         $this->assertEquals('success', (string) new Status('Success'));
         $this->assertEquals('success', (string) new Status('SUCCESS'));
diff --git a/tests/unit/TelephoneNumberTest.php b/tests/unit/TelephoneNumberTest.php
index cf7e4cd..c4eb673 100644
--- a/tests/unit/TelephoneNumberTest.php
+++ b/tests/unit/TelephoneNumberTest.php
@@ -7,14 +7,14 @@
 
 class TelephoneNumberTest extends TestCase
 {
-    public function testDiallingCode()
+    public function testDiallingCode(): void
     {
         $telephoneNumber = new TelephoneNumber(
             $diallingCode = '+44',
             $number = '00000000'
         );
 
-        $this->assertInternalType('string', $telephoneNumber->diallingCode());
+        $this->assertIsString($telephoneNumber->diallingCode());
         $this->assertEquals('44', $telephoneNumber->diallingCode());
 
         $telephoneNumber = new TelephoneNumber(
@@ -22,18 +22,18 @@ public function testDiallingCode()
             $number = '00000000'
         );
 
-        $this->assertInternalType('string', $telephoneNumber->diallingCode());
+        $this->assertIsString($telephoneNumber->diallingCode());
         $this->assertEquals('44', $telephoneNumber->diallingCode());
     }
 
-    public function testNumber()
+    public function testNumber(): void
     {
         $telephoneNumber = new TelephoneNumber(
             $diallingCode = '00',
             $number = '0113 000 0000'
         );
 
-        $this->assertInternalType('string', $telephoneNumber->number());
+        $this->assertIsString($telephoneNumber->number());
         $this->assertEquals('01130000000', $telephoneNumber->number());
 
         $telephoneNumber = new TelephoneNumber(
@@ -41,7 +41,7 @@ public function testNumber()
             $number = '0113-000-0000'
         );
 
-        $this->assertInternalType('string', $telephoneNumber->number());
+        $this->assertIsString($telephoneNumber->number());
         $this->assertEquals('01130000000', $telephoneNumber->number());
 
         $telephoneNumber = new TelephoneNumber(
@@ -49,7 +49,7 @@ public function testNumber()
             $number = '01130000000'
         );
 
-        $this->assertInternalType('string', $telephoneNumber->number());
+        $this->assertIsString($telephoneNumber->number());
         $this->assertEquals('01130000000', $telephoneNumber->number());
 
         $telephoneNumber = new TelephoneNumber(
@@ -57,7 +57,7 @@ public function testNumber()
             $number = '+441130000000'
         );
 
-        $this->assertInternalType('string', $telephoneNumber->number());
+        $this->assertIsString($telephoneNumber->number());
         $this->assertEquals('441130000000', $telephoneNumber->number());
     }
 }
diff --git a/tests/unit/TimeToLiveTest.php b/tests/unit/TimeToLiveTest.php
index 8fbff5f..9fd4ffd 100644
--- a/tests/unit/TimeToLiveTest.php
+++ b/tests/unit/TimeToLiveTest.php
@@ -9,51 +9,51 @@
 
 class TimeToLiveTest extends TestCase
 {
-    public function testNonIntegerTTLThrowsException()
+    public function testNonIntegerTTLThrowsException(): void
     {
         $this->expectException(TypeError::class);
 
         new TimeToLive('three minutes');
     }
 
-    public function testBelowMinimumTTLThrowsException()
+    public function testBelowMinimumTTLThrowsException(): void
     {
         $this->expectException(InvalidArgumentException::class);
 
         new TimeToLive('7199');
     }
 
-    public function testEqualToMinimumTTLInstantiates()
+    public function testEqualToMinimumTTLInstantiates(): void
     {
         $ttl = new TimeToLive('7200');
         $this->assertInstanceOf(TimeToLive::class, $ttl);
     }
 
-    public function testDefaultTTLHelper()
+    public function testDefaultTTLHelper(): void
     {
         $ttl = TimeToLive::defaultTtl();
         $this->assertInstanceOf(TimeToLive::class, $ttl);
         $this->assertEquals(TimeToLive::DEFAULT_TTL, (string) $ttl);
     }
 
-    public function testMinimumTTLHelper()
+    public function testMinimumTTLHelper(): void
     {
         $ttl = TimeToLive::minimumTtl();
         $this->assertInstanceOf(TimeToLive::class, $ttl);
         $this->assertEquals(TimeToLive::MINIMUM_TTL, (string) $ttl);
     }
 
-    public function testCastToString()
+    public function testCastToString(): void
     {
         $ttl = TimeToLive::defaultTtl();
-        $this->assertInternalType('string', (string) $ttl);
+        $this->assertIsString((string) $ttl);
         $this->assertEquals(TimeToLive::DEFAULT_TTL, (string) $ttl);
     }
 
-    public function testIntegerFunction()
+    public function testIntegerFunction(): void
     {
         $ttl = TimeToLive::defaultTtl();
-        $this->assertInternalType('integer', $ttl->integer());
+        $this->assertIsInt($ttl->integer());
         $this->assertEquals(TimeToLive::DEFAULT_TTL, $ttl->integer());
     }
 }