Strange null reference after updating to v4.3.0

[rudfoss-rr]

I have a very strange problem that I can't seem to figure out. I have a very simple test that worked fine in NUnit v3.14 (original) and in v4.2.2, but when I updated to v4.3.0 it suddenly fails with an actual value that is null.

  public void SupportsSubscopes()
  {
    var scope = PermissionScope.New("app");
    Assert.That(scope, Is.Not.Null);
    var expected = PermissionScope.New("app");
    Assert.That(expected, Is.Not.Null);
    Assert.That(scope, Is.EqualTo(expected));
}

If I debug the test and evaluate equality explicitly it is true, but the Assert.That line throws.

What could be the problem here? The code looks fine to me, but it seems that NUnit looses track of the actual value at some point. Could this be a bug in NUnit? I've reverted to 4.2.2 and it works fine.

[OsirisTerje]

A bit unsure about the class you're having there, does it have implicit operators or something?
You might be hitting #4898 (and #4902) , which is resolved in #4899.

If you make your code above into a small repro class, we can add it to the tests we have ongoing now, and check it out.

[rudfoss-rr]

You're right that it has an implicit operator for string conversion. It works fine with v4.2.2 but broke for v4.3.0. I suspect it is due to the same problem you linked to as it also selects the string overload.

I rebuilt the test in LINQPad and it fails there as well. This is the complete code using v4.3.0:

public record PermissionScope
{
	/// <summary>
	/// The full scope name.
	/// </summary>
	public string Name { get; private init; }
	
	private PermissionScope(string name) { Name = name; }

	public static PermissionScope New(string value) {
		return new(value);
	}
	
	public static implicit operator string(PermissionScope scope) => scope.Name;
}

void Main()
{
	var scope = PermissionScope.New("app");
	Assert.That(scope, Is.Not.Null);
	var expected = PermissionScope.New("app");
	Assert.That(expected, Is.Not.Null);
	Assert.That(scope, Is.EqualTo(expected));
}

[stevenaw]

Thanks for the report and repro @rudfoss-rr
I can confirm that this is the same issue as #4898 and that your repro currently passes when run on the branch to fix it.

The PR which will fix this is #4899. We will be publishing a 4.3.1 release for this

[rudfoss-rr]

Thanks for the quick response guys!

[OsirisTerje]

@rudfoss-rr 4.3.1 released now. Would appreciate if you could confirm it works for you. https://docs.nunit.org/articles/nunit/release-notes/framework.html#nunit-431----dec-21-2024

[rudfoss-rr]

@rudfoss-rr 4.3.1 released now. Would appreciate if you could confirm it works for you. https://docs.nunit.org/articles/nunit/release-notes/framework.html#nunit-431----dec-21-2024

✅Verified working. Thanks!