[Bug]: `.Should().NotBeNull()` assertion doesn't silence `CS8602 - Dereference of a possibly null reference.`

[radmorecameron]

Description

When asserting that a value isn't null with .Should().NotBeNull(), the [NotNull] attribute isn't applied to the input causing the CS8602 warning when it shouldn't (when not using a null-forgiving operator after)

Expected Behavior

There should be no warning when accessing a property that could be null after doing a notnull assertion

Actual Behavior

There is a null reference warning

Steps to Reproduce

This should be enough to reproduce:

        [Test]
        [Arguments("1234")]
        [Arguments("123")]
        public async Task ExampleTest(string? result)
        {
            const int length = 3;
            await result.Should().NotBeNull();
            if (length == result.Length)
            {
                await ValidateThreeLength();
            }
            else
            {
                await ValidateOtherLength();
            }
        }

        private Task ValidateThreeLength() => Task.CompletedTask;
        private Task ValidateOtherLength() => Task.CompletedTask;

TUnit Version

1.65.63/1.65.63-beta

.NET Version

.NET 10

Operating System

Windows

IDE / Test Runner

Visual Studio

Error Output / Stack Trace

CS8602 - Dereference of a possibly null reference.

Additional Context

Only happens with Should assertions, not with Assert.NotNull

IDE-Specific Issue?

• I've confirmed this issue occurs when running via dotnet test or dotnet run, not just in my IDE