public List<Release> findByReleaseKeys(Set<String> releaseKeys) {
    return releaseRepository.findByReleaseKeyIn(releaseKeys);
  }
@Test
  public void testFindByReleaseKeys() throws Exception {
    Release someRelease = mock(Release.class);
    Release anotherRelease = mock(Release.class);
    String someReleaseKey = "key1";
    String anotherReleaseKey = "key2";
    List<Release> someReleases = Lists.newArrayList(someRelease, anotherRelease);
    Set<String> someReleaseKeys = Sets.newHashSet(someReleaseKey, anotherReleaseKey);

    when(releaseRepository.findByReleaseKeyIn(someReleaseKeys)).thenReturn(someReleases);

    List<Release> result = releaseService.findByReleaseKeys(someReleaseKeys);

    assertEquals(someReleases, result);
  }