testfx: Improvement: ClassCleanup method to trigger after worker has executed all test methods not after all workers are complete

When running multiple [TestClass]es at the same time, why does the [ClassCleanup()] methods only get called at the very end?

File: UnitTest1.cs

    [TestClass]
    public class UnitTest1
    {
        [ClassInitialize()]
        public static void ClassInit(TestContext context) { }
    
        [ClassCleanup()]
        public static void ClassCleanup() { }
    
        [TestMethod]
        public void TestMethod() { }
    }

File: UnitTest2.cs

    [TestClass]
    public class UnitTest2
    {
        [ClassInitialize()]
        public static void ClassInit(TestContext context) { }
    
        [ClassCleanup()]
        public static void ClassCleanup() { }
    
        [TestMethod]
        public void TestMethod() { }
    }

The execution order is the following:

1. UnitTest2.ClassInit()
2. UnitTest2.TestMethod()
3. UnitTest1.ClassInit()
4. UnitTest1.TestMethod()
5. UnitTest2.ClassCleanup()
6. UnitTest1.ClassCleanup()

Notice that both [ClassCleanup] methods are executed at the end of the set; not after each TestClass is “done”.

But I expected a different behavior:

1. UnitTest2.ClassInit()
2. UnitTest2.TestMethod()
3. UnitTest2.ClassCleanup() - Expected
4. UnitTest1.ClassInit()
5. UnitTest1.TestMethod()
6. UnitTest1.ClassCleanup() - Expected

Microsoft’s Documentation - ClassCleanupAttribute Class says, “Identifies a method that contains code to be used after ALL the tests in the test class have run and to free resources obtained by the test class.”

But it appears to be run/executed late, after ALL tests have run. This seems wrong, and it is blocking my development.