Assert.EnterMultipleScope not detecting nullability properly

[artificialWave]

I've been rewriting all our tests that use Assert.Multiple to Assert.EnterMultipleScope but came across this issue that makes it currently impossible.

Given the following old code:

var restResponse = new RestResponse();

Assert.Multiple(() =>
{
    Assert.That(restResponse.StatusCode, Is.EqualTo(HttpStatusCode.OK));
    Assert.That(restResponse.Content, Is.Not.Null);
}

// restResponse.Content is definitely not null here
Assert.That(restResponse.Content.ToString(), Is.EqualTo("Test"));

And the code with EnterMultipleScope:

var restResponse = new RestResponse();

using (Assert.EnterMultipleScope())
{
    Assert.That(restResponse.StatusCode, Is.EqualTo(HttpStatusCode.OK));
    Assert.That(restResponse.Content, Is.Not.Null);
}

// restResponse.Content may be null here
Assert.That(restResponse.Content.ToString(), Is.EqualTo("Test"));

In the old version, the last assert does not produce a warning, because the analyzer knows that restResponse.Content is not null, or it would have failed earlier. In the newer version, it does produce a warning because it apparently does not know that restResponse.Content is definitely not null.

Both should work the same in detecting whether something can be null further on in the test.

[manfred-brands]

@artificialWave Thanks for reporting.
Yes, both should work the same.
I'll investigate this and fix it.