public void ShouldCallLibraryStateUpdate() { var updateLibraryStateCalled = false; dynamic caller = new ExpandoObject(); caller.updateLibraryState = new Action <object>((book) => { updateLibraryStateCalled = true; }); _mockClients.Setup(m => m.Caller).Returns((ExpandoObject)caller); _hub.GetLibraryState("test"); Assert.True(updateLibraryStateCalled); }