@Test
  public void testRegister() throws IOException {
    Key key = watcher.register(createDirectory(), ImmutableList.of(ENTRY_CREATE));
    assertThat(key.isValid()).isTrue();

    assertThat(watcher.isPolling()).isTrue();
  }
Tests for {@link PollingWatchService}.

@author Colin Decker
jimfs/src/test/java/com/google/common/jimfs/PollingWatchServiceTest.java