Assert.Equivalent throws NotSupportedException for types with getters returning ByRefLike types

[rabuckley]

The issue can be reproduced with the following test cases

#if NET6_0_OR_GREATER
public sealed class ByRefLikeParameters
{
    [Fact]
    public void Equivalent()
    {
        var expected = new RefParameterClass(42.ToString());
        var actual = new RefParameterClass(42.ToString());

        Assert.Equivalent(expected, actual);
    }

    [Fact]
    public void NotEquivalent()
    {
        var expected = new RefParameterClass2(42.ToString());
        var actual = new RefParameterClass2(2112.ToString());

        var ex = Record.Exception(() => Assert.Equivalent(expected, actual));

        Assert.IsType<EquivalentException>(ex);
        Assert.Equal(
            "Assert.Equivalent() Failure: Mismatched value on member 'Value'" + Environment.NewLine +
            "Expected: \"42\"" + Environment.NewLine +
            "Actual:   \"2112\"",
            ex.Message
        );
    }

    public sealed class RefParameterClass(string value)
    {
        public ReadOnlySpan<char> Value => value.AsSpan();
    }

    public sealed class RefParameterClass2(string value)
    {
        public ReadOnlySpan<char> ValueSpan => value.AsSpan();

        // Added so `NotEquivalent` has a getter to check.
        public string Value => value;
    }
}
#endif

which fail with

EquivalenceAssertsTests+ByRefLikeParameters.NotEquivalent [FAIL]
      Assert.IsType() Failure: Value is not the exact type
      Expected: typeof(Xunit.Sdk.EquivalentException)
      Actual:   typeof(System.NotSupportedException)
      Stack Trace:
        src\xunit.v3.assert.tests\Asserts\EquivalenceAssertsTests.cs(1991,0): at EquivalenceAssertsTests.ByRefLikeParameters.NotEquivalent()

EquivalenceAssertsTests+ByRefLikeParameters.Equivalent [FAIL]
  System.NotSupportedException : Specified method is not supported.
  Stack Trace:
       at System.Reflection.RuntimeMethodInfo.ThrowNoInvokeException()
       at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
       at System.Reflection.RuntimePropertyInfo.GetValue(Object obj, BindingFlags invokeAttr, Binder binder, Object[] index, CultureInfo culture)
       at System.Reflection.PropertyInfo.GetValue(Object obj)
    src\xunit.v3.assert.tests\Asserts\EquivalenceAssertsTests.cs(1978,0): at EquivalenceAssertsTests.ByRefLikeParameters.Equivalent()

The exception is thrown on invocation of the returned getter func.

This can be fixed by excluding ByRefLike return types from the getters dictionary

diff --git a/Sdk/AssertHelper.cs b/Sdk/AssertHelper.cs
index ca03cc2..9413079 100644
--- a/Sdk/AssertHelper.cs
+++ b/Sdk/AssertHelper.cs
@@ -136,6 +136,9 @@ static Dictionary<string, Func<object, object>> GetGettersForType(Type type) =>
 							&& p.GetMethod != null
 							&& p.GetMethod.IsPublic
 							&& !p.GetMethod.IsStatic
+#if NET6_0_OR_GREATER
+							&& !p.GetMethod.ReturnType.IsByRefLike
+#endif
 							&& p.GetIndexParameters().Length == 0
 							&& !p.GetCustomAttributes(typeof(ObsoleteAttribute)).Any()
 							&& !p.GetMethod.GetCustomAttributes(typeof(ObsoleteAttribute)).Any()

[bradwilson]

Extremely thorough write-up! Thank you! :)

[bradwilson]

Fix available in v2 2.9.3-pre.9
Fix available in v3 1.0.1-pre.7

https://xunit.net/docs/using-ci-builds