`.IsTypeOf<>()` is not available for `DateTime`

[Dona278]

We have a value returned from method which works with generic, so we want to check the returned type and seems that DateTime doesn't work in the same way of other types.

(assign null is only for example)

// This works
string? a = null;
await Assert.That(a).IsTypeOf<DateTime>();

// This not compile
DateTime? b = null;
await Assert.That(b).IsTypeOf<DateTime>();

[Dona278]

@thomhurst another case with our Result which is a struct.
I think it has something to do with TActual being a struct?

Workaround using <object>:

Result result = Result.Success();
await Assert.That<object>(result).IsTypeOf<Result>();

[thomhurst]

Yeah it's because the type system isn't picking it up from object because it's not a reference type I think.

Thing is if I make it an extension off of a generic T, then you're forced to specify both the source type and the expected type which isn't readable.

E.g.

IsTypeOf<object, Result>()

This is unfortunately a limitation of the C# type system. I think your above workaround is actually the cleanest solution right now