@Test
public void getFilesInFolder() throws Exception {

    when(driveDataStreams.getFilesInFolder(anyString())).thenReturn(Single.just(fileList));
    final TestObserver<FileList> testObserver = driveStreamsManager.getFilesInFolder(anyString()).test();
    testObserver.assertValue(fileList);
    testObserver.assertComplete();
    testObserver.assertNoErrors();
}