模擬功能調用僅一次

Question

我正在嘗試檢查同一文件中兩個功能的實現。 其中一個函數將調用另一個函數，我想檢查它是否確實發生。

import * as strings from './strings';

const generateUuidSpy = jest.spyOn(strings, 'generateUuid');

describe('getContextId()', () => {
  it('it should return a string id if given context and number', () => {
    const actual = strings.getContextId('testQueue', 5);
    const expected = 's1-s5';
    expect(typeof actual).toBe('string');
    expect(actual).toEqual(expected);
  });
  it('it should execute generateUuid()', () => {
    strings.getContextId('notTestQueue');
    expect(generateUuidSpy).toHaveBeenCalled();
  });
});

describe('generateUuid()', () => {
  it('it should return a 36 char UUID string', () => {
    generateUuidSpy.mockRestore();
    const actual = strings.generateUuid();
    const expected = /[a-f0-9]{8}-[a-f0-9]{4}-4[a-f0-9]{3}-[89aAbB][a-f0-9]{3}-[a-f0-9]{12}/;
    expect(actual.length).toBe(36);
    expect(typeof actual).toBe('string');
    expect(expected.test(actual)).toBe(true);
  });
});

但是我得到這個錯誤：

expect(jest.fn()).toHaveBeenCalled()

    Expected mock function to have been called, but it was not called.

      12 |   it('it should execute generateUuid()', () => {
      13 |     strings.getContextId('notTestQueue');
    > 14 |     expect(generateUuidSpy).toHaveBeenCalled();
         |                             ^
      15 |   });
      16 | });
      17 |

      at Object.toHaveBeenCalled (src/helpers/strings.test.js:14:29)

Answer 1

通過更改strings.js中導出的​​函數以導出其中包含每個函數的類來解決該問題。 然后在測試中，我啟動了該類的新實例，並將其用於測試。