How do I unit test a finalizer?

Question

I have the following class which is a decorator for an IDisposable object (I have omitted the stuff it adds) which itself implements IDisposable using

Answer 1

I use Appdomain (see sample below). Class TemporaryFile creates temporary file in constructor and delete's it in Dispose or in finalizer ~TemporaryFile().

Unfortunately, GC.WaitForPendingFinalizers(); doesn't help me to test finalizer.

    [Test]
    public void TestTemporaryFile_without_Dispose()
    {
        const string DOMAIN_NAME = "testDomain";
        const string FILENAME_KEY = "fileName";

        string testRoot = Directory.GetCurrentDirectory();

        AppDomainSetup info = new AppDomainSetup
                                  {
                                      ApplicationBase = testRoot
        };
        AppDomain testDomain = AppDomain.CreateDomain(DOMAIN_NAME, null, info);
        testDomain.DoCallBack(delegate
        {
            TemporaryFile temporaryFile = new TemporaryFile();
            Assert.IsTrue(File.Exists(temporaryFile.FileName));
            AppDomain.CurrentDomain.SetData(FILENAME_KEY, temporaryFile.FileName);
        });
        string createdTemporaryFileName = (string)testDomain.GetData(FILENAME_KEY);
        Assert.IsTrue(File.Exists(createdTemporaryFileName));
        AppDomain.Unload(testDomain);

        Assert.IsFalse(File.Exists(createdTemporaryFileName));
    }