NUnit TestCaseAttribute causing AmbiguousMatchException with NUnit VS Adapter

Question

I wrote a bunch of unit tests that utilized the TestCaseAttribute. These tests run great on my local machine when I use the ReSharper unit test runner. Unfortunately, when I run the tests through Visual Studio with the NUnit VS Adapter 2.0.0.0 I get the following output:

------ Run test started ------
NUnit VS Adapter 2.0.0.0 executing tests is started
Loading tests from D:\Projects\Ever\WebApp\Ever.UnitTests\bin\Debug\Ever.UnitTests.dll
Exception System.Reflection.AmbiguousMatchException, 
   Exception thrown executing tests in 
      D:\Projects\Ever\WebApp\Ever.UnitTests\bin\Debug\Ever.UnitTests.dll
NUnit VS Adapter 2.0.0.0 executing tests is finished
========== Run test finished: 0 run (0:00:00.8290488) ==========

We use the Visual Studio Online hosted build server for our build, and that relies on the test adapter to run our NUnit unit tests. This means I need to figure out a way to make this work with the attribute (much preferred) or I have to work around this limitation.

Do I have to abandon the use of the TestCaseAttribute because MSTest doesn't support parameterized tests^1,2?

Answer 1

After further debuging and testing I've concluded that the TestCaseAttribute isn't the cause of the issue. I'm answering my own question instead of deleting¹ in case anyone else falls into the same trap that I did.

The TestCaseAttribute works properly as you can see with the following tests. These tests run perfectly well via the VS Test Adapter and the ReSharper test runner.

[TestFixture]
public class SimpleReproAttempt
{
    [Test]
    [TestCase(true, false)]
    [TestCase(false, true)]
    public void DoesNotReproduceIssue(bool a, bool b)
    {
        Assert.IsTrue(a || b);
    }

    [Test]
    [TestCase("", false, true)]
    [TestCase(null, true, false)]
    public void DoesNotReproduceIssue(string a, bool b, bool c)
    {
        Assert.IsTrue(b || c);
        Assert.IsNullOrEmpty(a);
    }
}

The issue seems to be present only in tests that have an overloaded method with at least one of the overloads using async/await.

---

1: Editing my question based on this information would turn this into a chameleon question, and a chameleon via self answer is discouraged so I dismissed that option as well.