@Test
void testDownload() {

    final InputStream downloadResult = mock(InputStream.class);
    when(s3Client.getObject(any(GetObjectRequest.class), any(ResponseTransformer.class)))
            .thenReturn(downloadResult);
    final InputStream result = underTest.download();
    verify(s3Client).getObject(getObjectRequestArgumentCaptor.capture(), any(ResponseTransformer.class));
    final GetObjectRequest getObjectRequest = getObjectRequestArgumentCaptor.getValue();
    assertThat(getObjectRequest.bucket(), is(BUCKET_NAME));
    assertThat(getObjectRequest.key(), is(FILE_NAME));
    assertThat(result, is(downloadResult));
}