@Test
public void testExplicitCredentials() throws IOException, GeneralSecurityException {

  Credentials credentials = Mockito.mock(Credentials.class);
  configuration = new Configuration(false);
  configuration.set(BigtableOptionsFactory.BIGTABLE_HOST_KEY, TEST_HOST);
  configuration.set(BigtableOptionsFactory.PROJECT_ID_KEY, TEST_PROJECT_ID);
  configuration.set(BigtableOptionsFactory.INSTANCE_ID_KEY, TEST_INSTANCE_ID);
  configuration = BigtableConfiguration.withCredentials(configuration, credentials);
  BigtableOptions options = BigtableOptionsFactory.fromConfiguration(configuration);
  Credentials actualCreds = CredentialFactory.getCredentials(options.getCredentialOptions());
  Assert.assertSame(credentials, actualCreds);
}