Investigate snapshot testing

[TethysSvensson]

This might be related to #30

[stefnotch]

If you want a library with minimal dependencies, I can recommend https://github.com/rust-analyzer/expect-test

Rust-Analyzer comes with built-in support for it. It will show a "Update Tests (Expect)" button right in the IDE.

 #[test]
    fn test_formatting() {
        use crate::prelude::*;
        #[derive(Default)]
        struct NonSendSyncError(core::cell::Cell<()>);
        let non_send_sync_error = NonSendSyncError::default();
        let report = report!(non_send_sync_error);

        let expected = expect![[r#"
            "\n \u{1b}[97m● \u{1b}[1mAn object of type rootcause::report::ref_::tests::test_formatting::NonSendSyncError\u{1b}[0m\n ╰ src\\report\\ref_.rs:1157\n"
        "#]];
        expected.assert_debug_eq(&alloc::format!("{report}"));
    }