testSend_error() {
    fetchMock(new Request('https://www.google.com', {
      headers: new Headers(),
      method: 'GET',
    })).$returns(Promise.resolve(createFailedResponse()));

    mockControl.$replayAll();

    return verifySend('GET', 500 /* expectedStatusCode */);
  }
Verifies the send method in case of error response.
@return {!Promise<void>}