[英]Unit Testing redux async function with Jest
我对单元测试还很陌生,所以请原谅。
我有一个文件api.js
,其中包含该应用程序的所有API调用函数。 每个函数返回其诺言。 外观如下:
api.js
const api = {
getData() {
return superagent
.get(apiUrl)
.query({
page: 1,
});
},
}
现在来我要测试的redux异步操作。 看起来像这样:
getDataAction.js
export function getData(){
return dispatch => {
api.getData()
.end((err, data) => {
if (err === null && data !== undefined) {
console.log(data);
} else if (typeof err.status !== 'undefined') {
throw new Error(`${err.status} Server response failed.`);
}
});
}
}
现在,在我的测试文件中,我已经尝试过:
getDataAction.test.js
jest.mock('api.js');
describe('getData Action', () => {
it('gets the data', () => {
expect(store.dispatch(getData())).toEqual(expectedAction);
});
});
这给我抛出一个错误:
TypeError: Cannot read property 'end' of undefined
我究竟做错了什么 ? 现在,我可以使用Jest的默认自动模拟程序来模拟api.js,但是如何处理以end
运行回调函数的情况? 非常感谢您的帮助!
您的api
模拟程序需要返回一个函数,该函数返回具有end
函数的对象:
import api from 'api' //to set the implantation of getData we need to import the api into the test
// this will turn your api into an object with the getData function
// initial this is just a dumb spy but you can overwrite its behaviour in the test later on
jest.mock('api.js', ()=> ({getData: jest.fn()}));
describe('getData Action', () => {
it('gets the data', () => {
const result = {test: 1234}
// for the success case you mock getData so that it returns the end function that calls the callback without an error and some data
api.getData.mockImplementation(() => ({end: cb => cb(null, result)}))
expect(store.dispatch(getData())).toEqual(expectedAction);
});
it('it thows on error', () => {
// for the error case you mock getData so that it returns the end function that calls the callback with an error and no data
api.getData.mockImplementation(() => ({end: cb => cb({status: 'someError'}, null)}))
expect(store.dispatch(getData())).toThrow();
});
});
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