@Test
public void toString_returnsNotNull() {

  GoogleAdsClient client =
      GoogleAdsClient.newBuilder()
          .setCredentials(fakeCredentials)
          .setDeveloperToken(DEVELOPER_TOKEN)
          .setEnableGeneratedCatalog(enabledGeneratedCatalog)
          .build();
  String toString = client.toString();
  assertNotNull("toString should return a non-null string", toString);
  assertFalse("toString should return a non-empty string", toString.isEmpty());
}