@Test
public void testMultipleCustomSignerInitialization() throws IOException {

  Configuration config = new Configuration();
  config.set(CUSTOM_SIGNERS,
      "testsigner1:" + SignerForTest1.class.getName() + "," + "testsigner2:"
          + SignerForTest2.class.getName());
  SignerManager signerManager = new SignerManager("dontcare", null, config,
      UserGroupInformation.getCurrentUser());
  signerManager.initCustomSigners();
  Signer s1 = SignerFactory.createSigner("testsigner1", null);
  s1.sign(null, null);
  Assertions.assertThat(SignerForTest1.initialized)
      .as(SignerForTest1.class.getName() + " not initialized")
      .isEqualTo(true);
  Signer s2 = SignerFactory.createSigner("testsigner2", null);
  s2.sign(null, null);
  Assertions.assertThat(SignerForTest2.initialized)
      .as(SignerForTest2.class.getName() + " not initialized")
      .isEqualTo(true);
}