Jest Mocking promise not working with error Cannot read property 'then' of undefined in ExpressJS答案

【问题标题】：Jest Mocking promise not working with error Cannot read property 'then' of undefined in ExpressJSJest Mocking promise not working with error Cannot read property 'then' of undefined in ExpressJS
【发布时间】：2019-01-11 14:50:09
【问题描述】：

我正在尝试为我的 ExpressJS 应用程序实施测试。谷歌搜索后我找不到任何解决方案，请帮助并拯救我的一天......！

我遇到了错误。

TypeError: Cannot read property 'then' of undefined

       6 |   const arg1 = req.query.arg1;
       7 |   const arg2 = req.query.arg2;
    >  8 |   model.getExceptions(arg1, arg2, arg3)

测试文件如下

_test_/file.test.js:

import { getExceptions }  from '../file';
jest.mock('../model');

describe('file.js', () => {
  test('testing file...', () => {
    const req = {query: {arg1: 'SOME'}};
    const resp = {};
    expect(getExceptions(req, 'dd', resp)).toHaveLength(1);
    expect(getExceptions(req, 'ssd', resp)).toBe({test: 10});
  });
})

模拟文件：

_mocks_/model.js

const model = {
  getExceptions: (arg1, arg2, arg3) => {
  return new Promise((resolve, reject) => {
    process.nextTick(
      () =>
        arg1
          ? resolve({test: 110})
          : reject({
            error: 'not found.',
          })
    );
  })
}};

export default model;

要测试的代码文件：

文件.js

export const getExceptions = (req, res, next) => {
  const arg1 = req.query.arg1;
  const arg2 = req.query.arg2;
  model.getExceptions(arg1, arg2, req.arg3)
  .then(([rows]) => res.write(rows))
  .catch(next);
};

model.js

const model = {
  getExceptions: (arg1, arg2, arg3) => {
    try {
      return db.runQuery(qryName, [arg1, arg2, arg3]); // Custom function
    } catch (e) {
      throw new GatewayTimeoutError(e.message);
    }
  }
};

export default model;

如果需要更多详细信息，请告诉我。谢谢...

【问题讨论】：

标签： node.js express promise mocking jestjs

【解决方案1】：

我终于找到了答案。我会保留这个问题，以防有人遇到类似问题并寻找解决方案。

这是一个非常简单的错误 - 模拟文件夹应该带有双破折号。

正确的一个：

__mocks__

不正确的一个：

_mocks_

【讨论】：