React Native-在单元测试中模拟FormData [英] React Native - mocking FormData in unit tests

问题描述

我在测试thunk时遇到问题，因为许多API调用都使用FormData，而且我似乎无法弄清楚如何在测试中对此进行模拟.我正在使用Jest.

I'm having issues testing my thunks, as many of my API calls are using FormData, and I can't seem to figure out how to mock this in tests. I'm using Jest.

我的安装文件如下:

import 'isomorphic-fetch';

// Mocking the global.fetch included in React Native
global.fetch = jest.fn();

// Helper to mock a success response (only once)
fetch.mockResponseSuccess = body => {
  fetch.mockImplementationOnce(() =>
    Promise.resolve({ json: () => Promise.resolve(JSON.parse(body)) })
  );
};

// Helper to mock a failure response (only once)
fetch.mockResponseFailure = error => {
  fetch.mockImplementationOnce(() => Promise.reject(error));
};

但是，在所有需要FormData的测试中，我得到以下错误:

However, I get the following error on all tests that require FormData:

ReferenceError: FormData is not defined

我尝试从src/Libraries/Network/FormData下的react-native-mock导入FormData文件，但是没有用.

I've tried importing the FormData file from react-native-mock, under src/Libraries/Network/FormData, but it didn't work.

所以我想知道是否有人做过运气?

So I was wondering if anyone has had any luck doing this?

通常，我很难确定在React Native中模拟fetch请求的最佳方法，因此这里的任何建议都是不错的.我尝试了jest-fetch-mock lib(并打开了一个有关FormData的问题)，尝试使用nock进行设置(没有运气)，以及这种简单的Jest实现，但感觉还不对.

In general, I'm having a hard time figuring out the best way to mock fetch requests in React Native, so any advice here would be nice. I've tried the jest-fetch-mock lib (and opened an issue about FormData), tried setting up with nock (no luck), and this plain Jest implementation, but nothing feels right yet.

推荐答案

这是一个古老的问题，但是由于我已经在google的第一页中找到了它，因此请按照以下步骤操作:

This is an old question, but since I've found it in first page at google, here goes what I've done:

在测试开始时我添加了:

at the beginning of my test I added:

function FormDataMock() {
    this.append = jest.fn();
}
global.FormData = FormDataMock

这将确保所有地点都可以

this will make sure all places that do

const formData = new FormData()

将使用我的模拟.

当然，我只嘲笑了'append'方法，因为就我而言，这是我唯一需要的东西.我正在测试的函数返回了创建的FormData对象，我这样做是为了测试所有功能是否均按预期工作:

Of course, I've only mocked the 'append' method, since in my case it was the only thing I needed. The function that I was testing returned the created FormData object and I did this to test if all worked as expected:

const resultFormData = theFunction()
expect(resultFormData.append.mock.calls.sort(sortFunc)).toEqual(expected)

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