unit-testing - 如何在 Jest 中将模拟函数恢复为原始值？

Question

我在测试中模拟了一个类的静态函数，但我会影响其他测试。由于静态函数的性质，代码是:

  test('A', async () => {
    expect.assertions(2);
    let mockRemoveInstance = jest.fn(() => true);
    let mockGetInstance = jest.fn(() => true);
    User.removeInstance = mockRemoveInstance;
    User.getInstance = mockGetInstance;
    await User.getNewInstance();
    expect(mockRemoveInstance).toHaveBeenCalled();
    expect(mockGetInstance).toHaveBeenCalled();
  });

  test('B', () => {
    let mockRemoveInstance = jest.fn();
    const Singletonizer = require('../utilities/Singletonizer');
    Singletonizer.removeInstance = mockRemoveInstance;
    User.removeInstance();
    expect.hasAssertions();
    expect(mockRemoveInstance).toHaveBeenCalled();
  });

在 B 测试中 User.removeInstance() 仍然被 A 测试模拟，如何将 removeInstance() 重置为其类定义的原始函数？

Answer 1

您可以尝试使用 jest.spyOn
这样的事情应该为您恢复功能:-

    let mockRemoveInstance = jest.spyOn(User,"removeInstance");
    mockRemoveInstance.mockImplementation(() => true);

    User.removeInstance();
    expect(mockRemoveInstance).toHaveBeenCalledTimes(1);

    // After this restore removeInstance to it's original function

    mockRemoveInstance.mockRestore();