Running tests with ITestAction attributes leaks memory

[MatteS75]

Running this example:

    [SomeTestAttr]
    [TestFixtureSource(nameof(FixtureArgs))]
    public class Tests1
    {
        private static object[] FixtureArgs = Enumerable.Range(0, 100)
            .Select(a => new object[] {$"a{a:000}"})
            .ToArray();

        public Tests1(string arg)
        {
        }

        [Test]
        public void Test1([Range(0, 10)] int x)
        {
            Thread.Sleep(100);
            Assert.Pass();
        }
    }

    public class SomeTestAttrAttribute : Attribute, ITestAction
    {
        private object _data = Enumerable.Range(0, 1000000).ToArray();
        
        public void BeforeTest(ITest test)
        {
        }

        public void AfterTest(ITest test)
        {
        }

        public ActionTargets Targets { get; }
    }
    

From what we can see new attributes are created for each fixture, but never released.

This example is using TestFixtureSource to create many fixtures, but from what we can see the behavior is the same with multiple fixture classes.

[stevenaw]

This may've been "fixed" in #4034 through the introduction of caching the attribute instances

[lahma]

The earlier cache only was effective against attributes on methods. Created #4300 to address caching of test level metadata.

[OsirisTerje]

Seems this has been done.