TestCase with DataRow attribute with null parameter ignored

Description

When using MSTest.TestAdapter version 2.2.4 or higher, DataRow testcases with a null parameter are not discovered or executed. When using 2.2.3, all 3 testcases are discovered.

[TestMethod]
[DataRow(null)]
[DataRow("")]
[DataRow(" ")]
public void TestMethod(string parameter)
{

}

Steps to reproduce

Create a test project targetting .NET5 or .NET6, and make sure the version of the package MSTest.TestAdapter is 2.2.4 or higher. Add test method as seen above

Expected behavior

3 testcases should have been executed, but only the last two are executed

Actual behavior

Only the testcases with “” and " " as paramter are executed

Environment

MSTest.TestAdapter 2.2.4 or higher

[marnilss]

You need to set TestDataSourceDiscovery to DuringExecution in your test assembly as described here.

@Haplois, surely that is a temporary workaround, not a solution? So why close this issue?

Even though you have changed the implementation of how discovery of tests are done, shouldn’t the new one also be fixed to return the expected amount of testcases? Instead of saying - run the old behavior if you want something that works!!! Because I can’t see, nor has anyone else pointed it out, anything wrong with the sample provided by the TS - so it should work even with new discovery method.

[notcake]

Sounds like a duplicate of #1016, where test cases get ignored when they have the same display name.