Using TUnit Assertions in Unsafe Context

[JasonBock]

I'm taking a test code base that's currently targeting NUnit and moving it to TUnit. I have a test that exists within an unsafe context, and I'm running into an issue with asynchronous assertions. When I call this in my test (note that the containing class is marked as unsafe and it has to be unsafe for my testing scenario):

await Assert.That(wasCalled).IsTrue();

I'm getting this error:

error CS4004: Cannot await in an unsafe context

More details can be found here: https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/compiler-messages/unsafe-code-errors?f1url=%3FappId%3Droslyn%26k%3Dk(CS4004)#unsafe-context-restrictions.

If I try to remove the await like this (not ideal):

Assert.That(wasCalled).IsTrue().GetAwaiter().GetResult();

I get this diagnostics:

TUnitAssertion0002: Assert statements must be awaited - all TUnit assertions return Task

I can disable the diagnostic:

#pragma warning disable TUnitAssertions0002 // Assert statement not awaited
		Assert.That(wasCalled).IsTrue().GetAwaiter().GetResult();
#pragma warning restore TUnitAssertions0002 // Assert statement not awaited

Is that the only way to get around this?

[lofcz]

I second this issue, considering moving FastCloner to TUnit, but we need to run some tests with unsafe context. As an interim solution I'm considering throwing instead of asserting, which is not ideal, but at least it's not sync over async (see above).

[thomhurst]

Instead of throwing, it's probably easier to just bring in another 3rd party assertion library. You're not constrained to having to use TUnit's

[lofcz]

Why would I mix two assertion libraries? That's a pretty bad justification. Will think about this more but possibly this is a deal breaker.

[thomhurst]

I just mean that it's a hard limitation on TUnit's assertions unless you wanna do sync over async which I don't recommend.

I wonder if this limitation might go away in future .net versions when runtime async is out

[thomhurst]

Sorry I thought I'd replied to this.

Ultimately this is a limitation in TUnits assertion library because it relies on awaiting.

The only workaround really is the sync-over-async that you've suggested.

You can use TUnit with other assertions libraries, so maybe switching to a sync friendly assertion library makes more sense here