如何在玩笑中模拟AWS库

Question

我正在使用“ aws-amplify”库中的signIn方法。我在开玩笑地运行测试用例时无法从该库调用signIn方法。

码：

import { Auth } from "aws-amplify"; // import statement

//code for function
handleSubmit = async event => {
  event.preventDefault();
  this.setState({ isLoading: true });
  try {
    await Auth.signIn(this.state.username, this.state.password);
    this.props.history.push("/dashboard");
  } catch (e) {
    this.setState({ isLoading: false });
  }
}

测试文件：

it('calls event handler; "handleSubmit"', async()  => {   
    const componentInstance = Wrapper2.dive().instance();

    componentInstance.setState({
        isLoading : false,
        username : "demo",
        password : "demo"
    })
    const event = {
        preventDefault : () => {}
    };
    await componentInstance.handleSubmit(event);
    expect(componentInstance.state.isLoading).toEqual(true); 
});

在测试用例之上运行时，它总是进入handleSubmit（）函数的catch部分。

如何实现从“ aws-amplify”库调用signIn方法并测试正/负方案？

指导我，谢谢。

Answer 1

一种实现方法是模拟signIn函数并使用它。对于测试文件中的导入Auth

import { Auth } from "aws-amplify";

然后在调用handleSubmit函数模拟signIn函数之前

it('calls event handler; "handleSubmit"', async()  => {   
    const componentInstance = Wrapper2.dive().instance();

    componentInstance.setState({
        isLoading : false,
        username : "demo",
        password : "demo"
    })
    const event = {
        preventDefault : () => {}
    };
    Auth.signIn = jest.fn().mockImplementation(
     () => {
     // return whatever you want to test
    });
    await componentInstance.handleSubmit(event);
    expect(componentInstance.state.isLoading).toEqual(true); 
});

Answer 2

我就是这样做的：

import awsAmplify from 'aws-amplify'

jest.mock('aws-amplify')

it('does something', ()  => {
  awsAmplify.Auth.signIn.mockRejectedValue('mock error')
  awsAmplify.Auth.currentAuthenticatedUser.mockResolvedValue('mock user')
  ...
})