@Override
  public void deletePrefix(String prefix) {
    internalDeleteFiles(
        Streams.stream(listPrefix(prefix))
            .map(fileInfo -> BlobId.fromGsUtilUri(fileInfo.location())));
  }
@Test
  public void testDeletePrefix() {
    String prefix = "del/path/";
    String path1 = prefix + "data1.dat";
    storage.create(BlobInfo.newBuilder(TEST_BUCKET, path1).build());
    String path2 = prefix + "data2.dat";
    storage.create(BlobInfo.newBuilder(TEST_BUCKET, path2).build());
    String path3 = "del/skip/data3.dat";
    storage.create(BlobInfo.newBuilder(TEST_BUCKET, path3).build());

    assertThat(StreamSupport.stream(io.listPrefix(gsUri("del/")).spliterator(), false).count())
        .isEqualTo(3);

    io.deletePrefix(gsUri(prefix));

    assertThat(StreamSupport.stream(io.listPrefix(gsUri("del/")).spliterator(), false).count())
        .isEqualTo(1);
  }