More warnings CS8620 and CS8619 after update to >= 0.72

[maximerety]

Description

In a similar vein to #3422, I'm getting warnings in the following situations with asynchronous operations:

[Test]
[Arguments(null, null)]
[Arguments("test", "test")]
[Arguments(123, 123)]
public async Task Assert_That_With_Async_Object_Nullable_Parameters_Should_Not_Cause_Warnings(object? value, object? expected)
{
    // This should not produce CS8620 or CS8619 warnings, but triggers CS8620 warning
    await Assert.That(Task.FromResult(value)).IsEqualTo(expected);
}

[Test]
[Arguments("test", "test")]
[Arguments(123, 123)]
public async Task Assert_That_With_Async_Object_Parameter_And_Nullable_Expectation_Should_Not_Cause_Warnings(object value, object? expected)
{
    // This should not produce CS8620 or CS8619 warnings, but triggers CS8620 warning
    await Assert.That(Task.FromResult(value)).IsEqualTo(expected);
}

[Test]
[Arguments("test", "test")]
[Arguments(123, 123)]
public async Task Assert_That_With_Async_Object_Parameters_Should_Not_Cause_Warnings(object value, object expected)
{
    // This should not produce CS8620 or CS8619 warnings, but triggers CS8619 warning
    await Assert.That(Task.FromResult(value)).IsEqualTo(expected);
}

Reproduction

To reproduce the issue, you can edit the TUnit.Assertions.Tests/Bugs/Issue3422Tests.cs file (click for diff)

File: TUnit.Assertions.Tests/Bugs/Issue3422Tests.cs

  namespace TUnit.Assertions.Tests.Bugs;

  /// <summary>
  /// Tests for issue #3422: CS8620 and CS8619 warnings with object? parameters
  /// https://github.com/thomhurst/TUnit/issues/3422
  /// </summary>
  public class Issue3422Tests
  {
      [Test]
      [Arguments(null, null)]
      [Arguments("test", "test")]
      [Arguments(123, 123)]
      public async Task Assert_That_With_Object_Nullable_Parameters_Should_Not_Cause_Warnings(object? value, object? expected)
      {
          // This should not produce CS8620 or CS8619 warnings
          await Assert.That(value).IsEqualTo(expected);
      }

+     [Test]
+     [Arguments(null, null)]
+     [Arguments("test", "test")]
+     [Arguments(123, 123)]
+     public async Task Assert_That_With_Async_Object_Nullable_Parameters_Should_Not_Cause_Warnings(object? value, object? expected)
+     {
+         // This should not produce CS8620 or CS8619 warnings
+         await Assert.That(Task.FromResult(value)).IsEqualTo(expected);
+     }
+
+     [Test]
+     [Arguments("test", "test")]
+     [Arguments(123, 123)]
+     public async Task Assert_That_With_Async_Object_Parameters_And_Mix_Of_Nullability_Should_Not_Cause_Warnings(object value, object? expected)
+     {
+         // This should not produce CS8620 or CS8619 warnings
+         await Assert.That(Task.FromResult(value)).IsEqualTo(expected);
+     }
+
+     [Test]
+     [Arguments("test", "test")]
+     [Arguments(123, 123)]
+     public async Task Assert_That_With_Async_Object_Parameters_Should_Not_Cause_Warnings(object value, object expected)
+     {
+         // This should not produce CS8620 or CS8619 warnings
+         await Assert.That(Task.FromResult(value)).IsEqualTo(expected);
+     }

and run:

dotnet test --project TUnit.Assertions.Tests --framework net9.0 --treenode-filter '/*/*/Issue3422Tests/*' --output Detailed

which outputs:

./TUnit.Assertions.Tests/Bugs/Issue3422Tests.cs(35,27): warning CS8620: Argument of type 'Task<object>' cannot be used for parameter 'task' of type 'Task<object?>' in 'TaskAssertion<object> Assert.That<object>(Task<object?> task, string? expression = null)' due to differences in the nullability of reference types.
./TUnit.Assertions.Tests/Bugs/Issue3422Tests.cs(44,27): warning CS8620: Argument of type 'Task<object>' cannot be used for parameter 'task' of type 'Task<object?>' in 'TaskAssertion<object> Assert.That<object>(Task<object?> task, string? expression = null)' due to differences in the nullability of reference types.
./TUnit.Assertions.Tests/Bugs/Issue3422Tests.cs(52,33): warning CS8619: Nullability of reference types in value of type 'Task<object>' doesn't match target type 'Task<object?>'.