Question

我有以下文件要测试

functions.js

function funcOne() {
  return funcTwo()
}

function funcTwo() {
  return "func two"
}

module.exports = {
  funcOne,
  funcTwo
}

我想模拟funcTwo，以便在通过functions.funcOne调用时返回不同的字符串

functions.test.js

function mockFunctions() {
  const original = require.requireActual("./functions")
  return {
    ...original, //Pass down all the exported objects
    funcTwo: jest.fn(() => {
      return "my test func"
    })
  }
}
jest.mock("./functions", () => mockFunctions())
const functions = require.requireMock("./functions")

it("renders without crashing", () => {
  console.log(functions.funcOne())
})

它仍然显示“ func two”而不是“我的测试功能”。

有没有办法让模块保持完整并仅模拟一个特定方法？

Answer 1

这是一个解决方案：

functions.js：

function funcOne() {
  return exports.funcTwo();
}

function funcTwo() {
  return 'func two';
}

exports.funcOne = funcOne;
exports.funcTwo = funcTwo;

单元测试：

functions.spec.js

const functions = require('./functions');

describe('functions test suites', () => {
  it('funcOne', () => {
    const funcTwoSpyOn = jest.spyOn(functions, 'funcTwo').mockReturnValueOnce('my test func');
    const actualValue = functions.funcOne();
    expect(actualValue).toBe('my test func');
    expect(funcTwoSpyOn).toBeCalledTimes(1);
    funcTwoSpyOn.mockRestore();
  });
  it('funcTwo', () => {
    const actualValue = functions.funcTwo();
    expect(actualValue).toBe('func two');
  });
});

覆盖率100％的单元测试结果：

 PASS  src/stackoverflow/53889291/functions.spec.js
  functions test suites
    ✓ funcOne (5ms)
    ✓ funcTwo

--------------|----------|----------|----------|----------|-------------------|
File          |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
--------------|----------|----------|----------|----------|-------------------|
All files     |      100 |      100 |      100 |      100 |                   |
 functions.js |      100 |      100 |      100 |      100 |                   |
--------------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        3.199s

以下是完整的演示：https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/53889291

部分模拟模块

1 个答案: