Unity/C#, NUnit Parallelizable attribute

Question

I'm using Unity 2019.4.4f1 with NUnit 3.5.

I have set up a very simple parallel test between methods to see if it actually works, but they run in sync. I've been looking into NUnit parallel testing for some days, but I feel like I'm missing some very obvious thing.

using NUnit.Framework;
using System.Threading;

namespace NUnitTest
{
    [TestFixture]
    public class ParallelTest
    {
        [Test]
        [Parallelizable]
        public void Test01()
        {
            Debug.Log("Test 1 started");
            Thread.Sleep(2000);
            Debug.Log("Test 1 ended");
            Assert.IsTrue(true);
        }

        [Test]
        [Parallelizable]
        public void Test02()
        {
            Debug.Log("Test 2 started");
            Thread.Sleep(2000);
            Debug.Log("Test 2 ended");
            Assert.IsTrue(true);
        }
    }
}

In TestRunner, I run ParallelTest to run them both at the same time. I'd imagine the total runtime of ParallelTest should be near 2 seconds, but instead it's 4 seconds.

Any advice will be appreciated.

Answer 1

Unity has adapted the NUnit framework quite a bit. If there's one thing that Unity applications have never got along with, that would be async code.

The NUnit framework runs tests in parallel using multi-threaded test execution, which I imagine is the first thing Unity removed when creating their adaptation of the test runner.

If your code can be moved out of Unity and then imported via a DLL then I recommend you do that. That way your Unit Tests can use the raw NUnit framework! It's a pattern that I've adopted for all of my projects.

Long story short, I don't think you can.