使用 Jest 测试外部 Api 调用（使用获取函数）

Question

I am new to React/Redux and have implemented a basic example available on the official redux documentation page.

Need some help on how can I test the following functionality where in a plain javascript function calls an external API and my action creator is the one which calls that function.

How do I test the API call and my action creator function using Jest??

Here are the files that are present.

 import fetch from 'isomorphic-fetch' export const REQUESTS_POSTS ='REQUESTS_POSTS'; export const RECEIVE_POSTS ='RECEIVE_POSTS'; export const SELECT_SUBREDDIT ='SELECT_SUBREDDIT'; export const INVALIDATE_SUBREDDIT ='INVALIDATE_SUBREDDIT'; export function selectSubreddit(subreddit) { return{ type:SELECT_SUBREDDIT, subreddit } } export function invalidateSubreddit(subreddit) { return{ type:INVALIDATE_SUBREDDIT, subreddit } } function requestsPosts(subreddit) { return{ type:REQUESTS_POSTS, subreddit } } function receivePosts(subreddit, json) { return{ type:RECEIVE_POSTS, subreddit, posts:json.data.children.map(child=>child.data), receiveAt:Date.now() } } function fetchPosts(subreddit) { return dispatch=>{ dispatch(requestsPosts(subreddit)); return fetch(`https://www.reddit.com/r/${subreddit}.json`).then(response=>response.json()).then(json=>dispatch(receivePosts(subreddit,json))) } } function shouldFetchPosts(state, subreddit) { const posts = state.postsBySubreddit[subreddit]; if(;posts){ return true. }else if(posts;isFetching){ return false. }else{ return posts,didInvalidate } } export function fetchPostsIfNeeded(subreddit) { return (dispatch, getState) => { if(shouldFetchPosts(getState(),subreddit)){ return dispatch(fetchPosts(subreddit)) } } }

I have searched on the above thing but got various options like using 'nock' library, etc. I am very much confused on which is the actual right way to test it.

Answer 1

Check these links about testing async action creators using Jest:

http://redux.js.org/docs/recipes/WritingTests.html

https://medium.com/@ferrannp/unit-testing-with-jest-redux-async-actions-fetch-9054ca28cdcd

Answer 2

I understand that this question has been asked near 4 years ago. But it may be useful for guys and girls that will get in some kind of situation in the future.

It has no sense to test API that is external and uncontrolled by yourself. For example, you try to get the list of subreddits and assume that API call returns you some list. You add this list to your test file and test that result of the request is similar to this list. SUDDENLY, the list of subreddits changes, and now it isn't equal to your "expected" JSON. API still works correct, but test fails.

So the only thing that you should test - how do your methods treat results of the call. And for this purpose you shouldn't make real calls. Simply use nock or something like that.

Good luck for all who will read it!