_controller.WithCallTo(c => c.Index()).ShouldReturnContent();
_controller.WithCallTo(c => c.Index()).ShouldReturnContent("expected content");
_controller.WithCallTo(c => c.Index()).ShouldReturnContent("expected content", "content/type");
_controller.WithCallTo(c => c.Index()).ShouldReturnContent("expected content", "content/type", Encoding.UTF8);