Eli Lopian’s Blog (TypeMock)

Evil Singleton Mocking with Natural™ Mocks

Ok, so we all know that Singletons are Evil, and Hard to test but sometimes you just have to be bad.

We have added some more support for Singletons in the coming TypeMock version.
With Natural™ Mocks, it is quite easy to mock a Singleton. Here is how:

public class MyServer {
   public string Host {
      get {  return Singleton.Instance.GetHost(); }
   }
}

[Test]
public void TestSingleton()
{
   string expectedHost = "wow";
   using (RecordExpectations record = new RecordExpectations())
   {
      Singleton.Instance.GetHost();
      record.Return(expectedHost);
   }
   MyServer server = new MyServer();
   Assert.AreEqual(expectedHost, server.Host);
   MockManager.Verify();
}