Data tests (DynamicDataAttribute) with readonly structs do not work (default is passed)

[gurustron]

Describe the bug

If data test accepts readonly struct with fields (init prop will work) for some reason default struct is passed and not the actual value.

Steps To Reproduce

[DataTestMethod]
[DynamicData(nameof(TestDataDateOnly), DynamicDataSourceType.Method)]
public void TestDateOnly(DateOnly today, DateOnly inForceFrom)
{
	Assert.AreNotEqual(new DateOnly(),today);
	Assert.AreEqual(new DateOnly(2016, 4, 25),today);
}

public static IEnumerable<object[]> TestDataDateOnly()
{
	yield return new object[] { new DateOnly(2016, 4, 25), new DateOnly(2016, 4, 26)};
}
	
[DataTestMethod]
[DynamicData(nameof(TestDataCustomRecordStruct), DynamicDataSourceType.Method)]
public void TestCustomRecordStruct(MyStructField today)
{
	Assert.AreNotEqual(new MyStructField(),today);
	Assert.AreEqual(new MyStructField(2016),today);
}

public static IEnumerable<object[]> TestDataCustomRecordStruct()
{
	yield return new object[] { new MyStructField(2016)};
}
[DataTestMethod]
[DynamicData(nameof(TestDataCustomRecordStructProp), DynamicDataSourceType.Method)]
public void TestCustomRecordStructProp(MyStructProp today)
{
	Assert.AreNotEqual(new MyStructInitProp(),today);
	Assert.AreEqual(new MyStructProp(2016),today);
}

public static IEnumerable<object[]> TestDataCustomRecordStructProp()
{
	yield return new object[] { new MyStructProp(2016)};
}

// WORKS!	
[DataTestMethod]
[DynamicData(nameof(TestDataCustomRecordStructInitProp), DynamicDataSourceType.Method)]
public void TestCustomRecordStructInitProp(MyStructInitProp today)
{
	Assert.AreNotEqual(new MyStructInitProp(),today);
	Assert.AreEqual(new MyStructInitProp(2016),today);
}

public static IEnumerable<object[]> TestDataCustomRecordStructInitProp()
{
	yield return new object[] { new MyStructInitProp(2016)};
}

Expected behavior

All pass

Actual behavior

3 are failing (for DateOnly, MyStructField, MyStructProp)

Additional context

github repro
SO question

Workarounds

• use record structs or init-only props
• enclose data in custom wrapper class

[engyebrahim]

Hi @gurustron !
I confirm the behaviour you mentioned, thanks for taking the time to add the issue.

[Evangelink]

Hi @gurustron,

Your issue relates to the way MSTest serialize data to split test discovery and execution (for example in Visual Studio) and falls back under the bucket of this issue: #1462

[Evangelink]

Closing this one, please follow #1462 to get notifications about the fix.