public void CallsIntoClient() { var gitHubClient = Substitute.For<IGitHubClient>(); var client = new ObservableMiscellaneousClient(gitHubClient); client.RenderArbitraryMarkdown(new NewArbitraryMarkdown("# test")); gitHubClient.Miscellaneous.Received(1).RenderArbitraryMarkdown(Arg.Is<NewArbitraryMarkdown>(a => a.Text == "# test")); }