Question

我需要测试此功能：

import dependency from 'dependency';

export default values => (dispatch) => {
  dispatch(dependency(values));
  // More code
};

我进行了一项测试，该测试断言dispatch被称为dependency：

import functionToTest from 'function-to-test';

jest.mock('dependency', () => () => 'dependency res');

describe('functionToTest', () => {
    const dispatch = jest.fn();
    functionToTest({ foo: 'bar' })(dispatch);

    test('test', () => {
        expect(dispatch.mock.calls[0][0]).toBe('dependency res');
    });
});

我需要断言dependancy是用{ foo: 'bar' }调用的。我尝试命名依赖项模拟，但是当我console.log时它是未定义的：

import functionToTest from 'function-to-test';

const dependencyMock = jest.mock('dependency', () => () => 'dependency res');

describe('functionToTest', () => {
    const dispatch = jest.fn();
    functionToTest({ foo: 'bar' })(dispatch);

    test('test', () => {
        expect(dispatch.mock.calls[0][0]).toBe('dependency res');

        console.log(dependencyMock.mock.calls) // undefined
    });
});

我试图创建一个新的玩笑功能spy，希望我可以检查它的参数，但这返回了错误

import functionToTest from 'function-to-test';

const spy = jest.fn(() => 'save-form-data');

const dependencyMock = jest.mock('dependency', () => spy);

describe('functionToTest', () => {
    const dispatch = jest.fn();
    functionToTest({ foo: 'bar' })(dispatch);

    test('test', () => {
        expect(dispatch.mock.calls[0][0]).toBe('dependency res');

        console.log(dependencyMock.mock.calls) // undefined
    });
});

jest.mock()的模块工厂不允许引用任何范围外的变量。

Answer 1

您已经关闭！

您需要在传递给jest.mock的模块工厂函数中移动模拟函数。

然后，您只需要将dependency导入测试并检查它是否按预期被调用：

import functionToTest from 'function-to-test';
import dependency from 'dependency';  // <= dependency will be...

jest.mock('dependency', () =>
  jest.fn(() => 'dependency res')  // <= ...this mock function
);

describe('functionToTest', () => {
  it('should dispatch dependency', () => {
    const dispatch = jest.fn();
    functionToTest({ foo: 'bar' })(dispatch);

    expect(dispatch.mock.calls[0][0]).toBe('dependency res');  // Success!
    expect(dependency).toHaveBeenCalledWith({ foo: 'bar' });  // Success!
  });
});

请注意，默认情况下，babel-jest个提升jest.mock调用会在测试文件中的其他任何内容之前运行，因此传递给jest.mock的模块工厂函数必须完全独立。 / p>

在与Jest的依赖关系中模拟依赖关系？

1 个答案: