使用 Jest 的 mocking 值问题

Question

I'm trying to setup Jest within an existing project that is already set up with enzyme & jasmine. I've installed the jest packages and have set up an initial configuration, but now I'm running into an issue where the mock data is not being provided correctly. The same test works fine in the project when run without jest.

Here's the console output from the failing test:

macbook-pro:$ ./node_modules/.bin/jest 
 FAIL  spec/cookieSpec.js
  Cookie Parser should
    ✓ return an empty string (17 ms)
    ✓ return null (2 ms)
    ✕ return the session value (2 ms)
    ✕ be able to handle multiple cookies (2 ms)
    ✕ be able to handle badly formatted cookies (1 ms)

  ● Cookie Parser should › return the session value

    expect(received).toMatch(expected)

    Expected substring: "4332432423"
    Received string:    ""

      24 |     const result = getSessionId();
      25 |     expect(result).not.toBe(null);
    > 26 |     expect(result).toMatch('4332432423');
         |                    ^
      27 |     done();
      28 |   });
      29 | 

      at Object.<anonymous> (spec/cookieSpec.js:26:20)

Jest configuration in package.json:

"jest": {
    "verbose": true,
    "moduleNameMapper": {
      "\\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "spec/mocks/*.js",
      "\\.(css|less)$": "spec/mocks/*.js"
    },
    "moduleDirectories": [
      "node_modules"
    ],
    "setupFilesAfterEnv": [
      "jest-enzyme"
    ],
    "transform": {
      "^.+\\.jsx?$": "babel-jest"
    },
    "testEnvironment": "enzyme",
    "testEnvironmentOptions": {
      "enzymeAdapter": "react16"
    },
    "testMatch": [
      "**/spec/*Spec.js?(x)"
    ]
  },

Code from the test file cookieSpec.js

import {getSessionId} from 'Js/cookieReader.js';

describe('Cookie Parser should', function() {
  let _document = {cookie: ''};
  beforeEach(function() {
    global.document = _document;
  });

  it('return an empty string', function(done) {
    const result = getSessionId();
    expect(result).toBe('');
    done();
  });

  it('return null', function(done) {
    _document.cookie='ga=32213123';
    const result = getSessionId();
    expect(result).toBe('');
    done();
  });

  it('return the session value', function(done) {
    _document.cookie = 'connect.sid=4332432423';
    const result = getSessionId();
    expect(result).not.toBe(null);
    expect(result).toMatch('4332432423');
    done();
  });

  it('be able to handle multiple cookies', function(done) {
    _document.cookie='ga=32213123;connect.sid=4332432423';
    const result = getSessionId();
    expect(result).toBe('4332432423');
    done();
  });

  it('be able to handle badly formatted cookies', function(done) {
    _document.cookie=' ga=32213123;connect.sid= 4332432423';
    const result = getSessionId();
    expect(result).toBe('4332432423');
    done();
  });
});

Answer 1

It turns out that there was setup code that established the cookie mocks that was running for jasmine but not for jest. Once the mocks were established for jest, the tests passed.