我正在尝试测试此简单的api模块:
import fetch from 'isomorphic-fetch';
export const getJson = (endpoint: string) => {
const options = { credentials: 'include', method: 'GET' };
return fetch(endpoint, options)
.then(response => response.json()
.then(json => {
if (response.ok) return json;
return Promise.reject(json.errors);
})
)
.catch(error => {
if (error.constructor === Array) return error;
return [error.message];
});
};
通过此测试,我在其中模拟访存:
import { getJson } from '../api';
const mockResponse = (status, statusText, response) => {
return new window.Response(response, {
status: status,
statusText: statusText,
headers: {
'Content-type': 'application/json'
}
});
};
describe('api middleware', () => {
describe('getJson', () => {
it('should return the response on success', () => {
const expected = { data: ['data'], meta: {} };
const body = JSON.stringify(expected);
window.fetch = jest.fn().mockImplementation(() =>
Promise.resolve(mockResponse(200, null, body)));
return getJson('http://endpoint').then(actual => expect(actual).toEqual(expected));
});
});
});
但是测试失败并显示:
Expected value to equal:
{"data": ["data"], "meta": {}}
Received:
["Unexpected end of JSON input"]
Difference:
Comparing two different types of values:
Expected: object
Received: array
我无法弄清楚为什么它不起作用。为什么会收到“ JSON输入意外结束”错误?我如何在测试中成功模拟本地提取?在this medium post中,它的完成方式基本上相同。
最佳答案
因此,显然测试仍在使用全局提取库,而不是我的补丁版本。解决方案是:
删除“ isomorphic-fetch”模拟(在项目根目录的__mocks__
中)。
使用import 'isomorphic-fetch;
在我的项目的根目录中一次导入“ isomorphic-fetch”
删除我的api模块顶部的“ isomorphic-fetch”导入(因为它已经在入口点导入了)
将测试更新为:
测试:
// to make the Response constructor available
import 'isomorphic-fetch';
import { getJson } from '../api';
describe('api middleware', () => {
describe('getJson', () => {
beforeEach(() => {
window.fetch = jest.genMockFunction();
});
it('should return the response on success', () => {
const expected = { data: ['data'], meta: {} };
const body = JSON.stringify(expected);
const init = { status: 200, statusText: 'OK' };
window.fetch.mockReturnValueOnce(Promise.resolve(new Response(body, init)));
return getJson('http://endpoint').then(actual => expect(actual).toEqual(expected));
});
});
});