如何对依赖于另一个方法的方法进行单元测试？

Question

我有一个 React 和 Redux 项目，我正在尝试使用 Chai 测试框架进行单元测试。现在我正在为我拥有的reducer 编写一个测试，这个reducer 处理的几个动作调用了辅助方法。这是一个例子：

formsReducer.js：

import * as types from '../constants/actionTypes';
import objectAssign from 'object-assign';
import initialState from './initialState';
import formsHelper from '../utils/FormsHelper';
export default function formsReducer(state = initialState.forms, action) {
  switch (action.type) {
    case types.UPDATE_PRODUCT: {
        let formBlueprints = formsHelper.getFormsByProductId(action.product.id);
        formBlueprints = formsHelper.addOrRemoveMnDisclosure(formBlueprints, action.stateOfResidence.id);
        return objectAssign({}, state, {blueprints: formBlueprints, instances: []});
    }
  }
}

如您所见，如果我测试此方法，我也依赖 formsHelper.getFormsByProductId 和 formsHelper.addOrRemoveMnDisclosure 方法通过。我应该如何测试这个减速器/动作？当某个 product.id 传递给这些方法时，我是否应该制作一组可以从这些方法返回的单独测试数据？

Answer 1

您有几个选择：您可以使用nock 拦截请求（如果它进行http 调用）或使用proxyquire 模拟依赖项。假设您将mocha 与chai 结合使用，这里有一些示例可以帮助您入门。

nock 例子

const nock = require('nock');

describe('your test', () => {
  if('should do things', () => {
    nock('http://your-domain')
      .get('/forms/1') // <---- or any other resource
      .reply(200, { /* your response object for testing */ });

    /* Your regular test */
  });
});

proxyquire例子

const proxyquire = require('proxyquire');

describe('your test', () => {
  if('should do things', () => {
    const formsReducer = proxyquire.noCallThru().load('../reducers/forms', {
      formsHelper: {
        /* any keys you need mocked/replaced for your test */
        getFormsByProductId: id => return { /* mock response */ }
      }
    });

    /* Your regular test */
  });
});