String getUrl() {
    return "http://" + this.httpServer.getInetAddress().getHostAddress() + ":" + this.httpServer.getLocalPort();
  }
@Test
  public void return_http_response_with_code_500_and_exception_message_as_body_when_action_throws_exception() throws IOException {
    Response response = call(underTest.getUrl() + "/failing");

    assertThat(response.code()).isEqualTo(500);
    assertThat(response.body().string()).isEqualTo(FAILING_ACTION.getMessage());
  }