@Test
public void shouldReturnErrorGivenNullPermission() throws Exception {

  Single<Boolean> reactiveStream = requestPermissionInteractor.buildReactiveStream(null);
  assertThat(reactiveStream).isNotNull();
  TestObserver<Boolean> testObserver = reactiveStream.test();
  testObserver.assertError(IllegalArgumentException.class);
  testObserver.assertErrorMessage("Invalid Permission");
  testObserver.assertNotComplete();
}