@Test
public void shouldAssignImageToViewOnPostExecute(){

    AssignThumbnailAsyncTask task = new AssignThumbnailAsyncTask(imageView, photoCaptureHelper);
    ThumbnailDrawable thumbnailDrawable = mock(ThumbnailDrawable.class);
    given(imageView.getDrawable()).willReturn(thumbnailDrawable);
    given(thumbnailDrawable.getAssignThumbnailAsyncTask()).willReturn(task);
    Bitmap bitmap = mock(Bitmap.class);
    task.onPostExecute(bitmap);
    verify(imageView).setImageBitmap(bitmap);
}