How to check Toast window, on android test-kit Espresso

If we read the following public document, we can check other window.
Using inRoot to target non-default windows

onView(withText("South China Sea"))
  .inRoot(withDecorView(not(is(getActivity().getWindow().getDecorView()))))
  .perform(click());

But, I think this is not cool.

We can create a custom matcher.
Toast window has the WindowManager.LayoutParams.TYPE_TOAST.

The followinf code is sample.

    /**
     * Matcher that is Toast window.
     */
    public static Matcher<Root> isToast() {
        return new TypeSafeMatcher<Root>() {

            @Override
            public void describeTo(Description description) {
                description.appendText("is toast");
            }

            @Override
            public boolean matchesSafely(Root root) {
                int type = root.getWindowLayoutParams().get().type;
                if ((type == WindowManager.LayoutParams.TYPE_TOAST)) {
                    IBinder windowToken = root.getDecorView().getWindowToken();
                    IBinder appToken = root.getDecorView().getApplicationWindowToken();
                    if (windowToken == appToken) {
                        // windowToken == appToken means this window isn't contained by any other windows.
                        // if it was a window for an activity, it would have TYPE_BASE_APPLICATION.
                        return true;
                    }
                }
                return false;
            }
        };
    }