Hi, how do I test an extension function of a Toast or Progressbar?

But I just want to test that a toast extension function is working

You can use assertThat. We actually can now test for toast messages using robolectric. The example below is how our team is doing this for now: @Test public void ccButtonDisplaysToast() throws NullPointerException { Button ccRedButton = (Button) findViewById(R.id.cc_red); cc_red.performClick(); --> this calls the actual onClickListener implementation which has the toast. ShadowLooper.idleMainLooper(YOUR_TIME_HERE); --> This may help you. assertThat(ShadowToast.getTextOfLatestToast().toString(), equalTo("TEST_YOUR_TEXT_HERE")); } Hope this helps