我正在尝试模拟作为默认导出导出的异步函数,但我得到的只是 TypeError:无法读取未定义的属性'then'
我要模拟的是 config.js :
const configureEnvironment = async (nativeConfig) => {
return { await whatever() }
}
我正在测试的文件是 Scene.js :
import configureEnvironment from './config';
class Scene extends React.Component {
constructor(props) {
nativeConfig = {};
configureEnfironment(nativeConfig).then((config) => {
// Do stuff
}
}
}
我的测试文件是 Scene.test.js :
let getScene = null;
const configureEnvironmentMock = jest.fn();
describe('Scene', () => {
jest.mock('./config', () => configureEnvironmentMock);
const Scene = require('./Scene').default;
getScene = (previousState) => {
return shallow(
<Scene prevState={previousState}>
<Fragment />
</Scene>,
);
};
it('calls configureEnvironment with the nativeConfig', async () => {
expect.assertions(1);
const nativeConfig = {};
getScene(nativeConfig);
expect(configureEnvironmentMock).toHaveBeenCalledWith(nativeConfig);
});
});
但是,运行测试的结果是:
TypeError: Cannot read property 'then' of undefined
我了解问题出在我模拟configureEnvironment的方式上,但是我无法使其正常工作。
我还尝试过模拟以下功能:
jest.mock('./config', () => {
return {
default: configureEnvironmentMock,
};
});
但结果是:
TypeError: (0 , _config2.default) is not a function
答案 0 :(得分:1)
模拟模块默认导出的一种干净简单的方法是结合使用jest.spyOn
和mockImplementation
之类的功能。
这是一个基于上面的代码片段的工作示例:
config.js
const whatever = async () => 'result';
const configureEnvironment = async (nativeConfig) => await whatever();
export default configureEnvironment;
Scene.js
import * as React from 'react';
import configureEnvironment from './config';
export class Scene extends React.Component {
constructor(props) {
super(props);
configureEnvironment(props.prevState).then((config) => {
// Do stuff
});
}
render() {
return null;
}
}
Scene.test.js
import React, { Fragment } from 'react';
import { shallow } from 'enzyme';
import { Scene } from './Scene';
import * as config from './config';
describe('Scene', () => {
const mock = jest.spyOn(config, 'default'); // spy on the default export of config
mock.mockImplementation(() => Promise.resolve('config')); // replace the implementation
const getScene = (previousState) => {
return shallow(
<Scene prevState={previousState}>
<Fragment />
</Scene>,
);
};
it('calls configureEnvironment with the nativeConfig', async () => {
expect.assertions(1);
const nativeConfig = {};
getScene(nativeConfig);
expect(mock).lastCalledWith(nativeConfig); // SUCCESS
});
});
答案 1 :(得分:0)
您可以开玩笑地嘲笑任何东西,像这样
jest.mock('@material-ui/core/withWidth', () => ({
__esModule: true,
isWidthUp: jest.fn((a, b) => true),
default: jest.fn(fn => fn => fn)
}))