Unit Testing Event Assignments

A quick note on how to test for event assignments using NUnit and Rhino.Mocks for stub and mock scenarios.

Stub scenario:

1. [Test]
2. public static void AssignPageEventHandlers_SetsPageEventHandlers()
3. {
4.     var stubView = MockRepository.GenerateStub<INavigationPageBaseView>();
5.     var obj = new TestNavigationControllerRoot(stubView);
6.     obj.AssignPageEventHandlers();
7.     stubView.AssertWasCalled(v => v.PreInit += Rhino.Mocks.Arg<EventHandler>.Matches(eh => eh.Method.Name.Equals("PagePreInit")));
8.     stubView.AssertWasCalled(v => v.Init += Rhino.Mocks.Arg<EventHandler>.Matches(eh => eh.Method.Name.Equals("PageInit")));
9.     stubView.AssertWasCalled(v => v.Load += Rhino.Mocks.Arg<EventHandler>.Matches(eh => eh.Method.Name.Equals("PageLoad")));
10. }

Mock scenario:

1. [Test]
2. public void PageLoadMasterController_ExpectedBehavior()
3. {
4.     var stubExProcessor = MockRepository.GenerateStub<IExceptionProcessor>();
5.     stubExProcessor.Stub(e => e.GetCurrentUserErrorMessage()).Return("msg");
6.  
7.     var mockView = Mocks.StrictMock<IErrorView>();
8.     using (Mocks.Ordered())
9.     {
10.         Expect.Call(() => mockView.PreInit += Arg<EventHandler>.Matches(eh => eh.Method.Name.Equals("PagePreInit")));
11.         Expect.Call(() => mockView.Init += Arg<EventHandler>.Matches(eh => eh.Method.Name.Equals("PageInit")));
12.         Expect.Call(() => mockView.Load += Arg<EventHandler>.Matches(eh => eh.Method.Name.Equals("PageLoad")));
13.         Expect.Call(mockView.IssueMessageLiteralText = "msg");
14.     }
15.     Mocks.ReplayAll();
16.     var obj = new ErrorController(mockView) { NavigationBuilderFactory = MockNavBuilderFactory, NavigationMasterController = MockNavigationMasterController };
17.     obj.PageLoad(stubExProcessor);
18.     Mocks.VerifyAll();
19. }