Refactoring suggestion for managing diagnostic metadata.

[JohanLarsson]

I have found it to be nice to have classes like:

internal static class NUNIT17TestCaseSourceIsMissing
{
	public const string DiagnosticId = "NUNIT_17";

	internal static readonly DiagnosticDescriptor Descriptor = new DiagnosticDescriptor(
            DiagnosticId ,
            "TestCaseSource argument does not specify an existing member.",
            "TestCaseSource argument does not specify an existing member.",
            Categories.Usage,
            DiagnosticSeverity.Error,
            true);
}

Reasons I like it is:

• We group constants that belong together.
• Enables easy scanning of what rule id's we use.

I'm not married to this idea, just thought I'd write an issue about it and see what you think.

[mikkelbu]

I think it makes sense to group the constants together that belong together. Now it is - in some cases - too easy to select the wrong constant by mistake, as most of them "lives" in a general namespace and in a general class, like TransformToConstraintModelDescription in NUnit.Analyzers.Constants.CodeFixConstants.

I find the current structuring less than ideal. The reason for why I have not created an issue for this, is that I have not had time to think about it in detail. TLDR I agree with the issue and thanks for reporting this.

[JohanLarsson]

I'll write a PR with the refactoring then.