javascript - Jest - 调用模拟函数不计算在内

Question

我对调用计数 next 函数感到困惑。我正在使用 formidable 来处理表单。

这是我的代码:

const ctrl = {};
ctrl.addAccount = async (req, res, next) => {
  const form = new formidable.IncomingForm();

  form.multiples = true;

  form.parse(req, async function (err, fields, files) {

    const accountType = _.get(fields, 'accountType');


    if (accountTypes.indexOf(accountType) === -1) {
      // next is mocked, call counted in different test
      next(boom.badRequest('Account type is not supported'));
      return;
    }

    try {
      // some logic
      await validator.validate(fields);

      // Some logic
      res.status(200).send("OK");

    } catch (err) {
      next(boom.badRequest(err)); // next is mocked but call didn't count
    }
  });
};

module.exports = ctrl;

这是测试:

it.only('return Error on validation error', async () => {
  const fields = {
    accountType: "moderator",
    title: "Title"
  };
  const files = {};

  const formidableFn = {
    IncomingForm: jest.fn(),
    parse: jest.fn((req, callback) => callback(undefined, fields, files)),
    multiples: true
  };
  const formidable = require('formidable');
  formidable.mockImplementation(() => formidableFn);

  const { addAccount } = require('./add');

  const mReq = {
    body: {},
    dbConnection: jest.fn()
  };

  const mRes = {
    send: jest.fn().mockReturnThis()
  };

  const mNext = jest.fn().mockName('next function');

  await addAccount(mReq, mRes, mNext);

  expect(formidableFn.parse).toHaveBeenCalledTimes(1);
  expect(formidableFn.parse).toHaveBeenCalledWith(mReq, expect.any(Function));

  expect(mNext).toHaveBeenCalledTimes(1); // I've got 0 instead of 1
});

我期望 mNext 被调用一次。但我得到了 0。我在 catch 语句中通过 console.log(next) 检查，我可以看到 next 函数是模拟函数。

在不同的测试中，我正在测试 next(boom.badRequest('Account type is not support'));
已计算在内。

Answer 1

这是单元测试解决方案:

例如

add.js:

const formidable = require('formidable');
const _ = require('lodash');
const validator = require('./validator');

const accountTypes = ['moderator'];
const boom = {
  badRequest: (err) => err,
};

const ctrl = {};
ctrl.addAccount = async (req, res, next) => {
  const form = new formidable.IncomingForm();

  form.multiples = true;

  form.parse(req, async function(err, fields, files) {
    const accountType = _.get(fields, 'accountType');

    if (accountTypes.indexOf(accountType) === -1) {
      next(boom.badRequest('Account type is not supported'));
      return;
    }
    try {
      await validator.validate(fields);
      res.status(200).send('OK');
    } catch (err) {
      next(boom.badRequest(err));
    }
  });
};

module.exports = ctrl;

validator.js:

const validator = {
  validate: async (fields) => {
    console.log('validate fields');
  },
};

module.exports = validator;

add.test.js:

const formidable = require('formidable');
const { addAccount } = require('./add');
const validator = require('./validator');

jest.mock('formidable', () => {
  const mForm = {
    multiples: false,
    parse: jest.fn(),
  };
  return {
    IncomingForm: jest.fn(() => mForm),
  };
});

describe('59459690', () => {
  afterEach(() => {
    jest.resetAllMocks();
    jest.restoreAllMocks();
  });
  it('return Error on validation error', async () => {
    const fields = {
      accountType: 'moderator',
      title: 'Title',
    };
    const files = {};
    const form = new formidable.IncomingForm();
    let originalCallback;
    form.parse.mockImplementation((req, callback) => {
      originalCallback = callback;
    });
    const mError = new Error('validation error');
    jest.spyOn(validator, 'validate').mockRejectedValueOnce(mError);

    const mReq = {
      body: {},
      dbConnection: jest.fn(),
    };
    const mRes = {
      send: jest.fn().mockReturnThis(),
    };
    const mNext = jest.fn().mockName('next function');

    await addAccount(mReq, mRes, mNext);
    await originalCallback(undefined, fields, files);

    expect(form.parse).toHaveBeenCalledTimes(1);
    expect(form.parse).toHaveBeenCalledWith(mReq, expect.any(Function));

    expect(mNext).toHaveBeenCalledTimes(1);
  });
});

带有覆盖率报告的单元测试结果:

 PASS  src/stackoverflow/59459690/add.test.js
  59459690
    ✓ return Error on validation error (8ms)

--------------|----------|----------|----------|----------|-------------------|
File          |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
--------------|----------|----------|----------|----------|-------------------|
All files     |    79.17 |       50 |    66.67 |    78.26 |                   |
 add.js       |       85 |       50 |      100 |    84.21 |          20,21,25 |
 validator.js |       50 |      100 |        0 |       50 |               2,3 |
--------------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        3.82s, estimated 8s

源代码:https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/59459690