@Override
  public CiConfiguration loadConfiguration() {
    String revision = system.envVariable(PROPERTY_COMMIT);
    if (isEmpty(revision)) {
      LoggerFactory.getLogger(getClass()).warn("Missing environment variable " + PROPERTY_COMMIT);
    }
    return new CiConfigurationImpl(revision, getName());
  }
@Test
  public void log_warning_if_missing_commit_variable() {
    setEnvVariable("CIRRUS_PR", "1234");

    CiConfiguration configuration = underTest.loadConfiguration();

    assertThat(configuration.getScmRevision()).isEmpty();
    assertThat(logs.logs(Level.WARN)).contains("Missing environment variable CIRRUS_CHANGE_IN_REPO");
  }