@Test
public void shouldReturnDefaultErrorMessageGivenANullException() throws Exception {

  DefaultErrorBundle defaultErrorBundle = new DefaultErrorBundle(null);
  String errorMessage = defaultErrorBundle.getErrorMessage();
  assertThat(errorMessage).isNotNull();
  assertThat(errorMessage).isInstanceOf(String.class);
  assertThat(errorMessage).isEqualTo("Unknown error");
}