测试 createAsyncThunk Redux Toolkit Jest

Question

我是 redux 工具包库的新手，尤其是在测试方面。我浏览了文档并阅读了一堆关于这个主题的帖子和文章，但仍然很挣扎。我构建了一个简单的待办事项应用程序，并包含了几个 API 请求来涵盖异步情况。不过，测试这些结果有点挑战性。我希望就我的代码以及可以改进的地方获得一些建议和反馈。我还想对测试 createAsyncThunk 切片是否有意义提出一些意见。注意:我对测试 API 调用本身不感兴趣，并使用模拟数据重新创建成功的请求。

build 性的批评非常有帮助，将不胜感激

请看一下我的切片文件并进行测试

postSlice.ts

import { createSlice, createAsyncThunk } from "@reduxjs/toolkit";
import { RootState } from "../../store";
import axios from "axios";

export type Post = {
  userId: number;
  id: number;
  title: string;
  body: string;
};

export type PostsState = {
  posts: Post[];
  loading: boolean;
  error: null | string;
};

export const initalPostState: PostsState = {
  posts: [],
  loading: false,
  error: null,
};

export const fetchAllPosts = createAsyncThunk(
  "posts/allPosts",
  async (data, { rejectWithValue }) => {
    try {
      const response = await axios.get(
        `https://jsonplaceholder.typicode.com/posts`
      );
      return (await response.data) as Post[];
    } catch (err) {
      if (!err.response) {
        throw err;
      }
      return rejectWithValue(err.response.data);
    }
  }
);

export const fetchSuccessful = fetchAllPosts.fulfilled;
export const fetchPending = fetchAllPosts.pending;
export const fetchFailed = fetchAllPosts.rejected;

const postsSlice = createSlice({
  name: "Posts",
  initialState: initalPostState,
  reducers: {},
  extraReducers: (builder) => {
    builder.addCase(fetchSuccessful, (state, { payload }) => {
      state.posts = payload;
      state.loading = false;
    });
    builder.addCase(fetchPending, (state, action) => {
      state.loading = true;
    });
    builder.addCase(fetchFailed, (state, action) => {
      state.error = action.error.message
        ? action.error.message
        : "Failed to load data";
      state.loading = false;
    });
  },
});

export const selectPosts = (state: RootState) => state.fetchedPosts;
export const fetchedPostsReducer = postsSlice.reducer;

测试

postSlice.test.ts

import {
  initalPostState,
  fetchPending,
  fetchFailed,
  selectPosts,
  fetchSuccessful,
  fetchedPostsReducer,
} from "./postsSlice";
import { Post, PostsState } from "./postsSlice";
import store, { RootState } from "../../store";

const appState = store.getState();

describe("postsSlice", () => {
  describe("Posts State, Posts Action and Selector", () => {
    it("should set loading state on true when API call is pending", async (done) => {
      // Arrange

      // Act
      const nextState: PostsState = await fetchedPostsReducer(
        initalPostState,
        fetchPending
      );
      // Assert
      const rootState: RootState = { ...appState, fetchedPosts: nextState };
      expect(selectPosts(rootState).loading).toBeTruthy();
      expect(selectPosts(rootState).error).toBeNull();
      done();
    });

    it("should set error state when API call is rejected", async (done) => {
      // Arrange
      const response = {
        message: "Network request failed",
        name: "error",
      };
      // Act
      const nextState: PostsState = await fetchedPostsReducer(
        initalPostState,
        fetchFailed(response, "")
      );
      // Assert
      const rootState: RootState = { ...appState, fetchedPosts: nextState };
      expect(selectPosts(rootState).loading).toBeFalsy();
      expect(selectPosts(rootState).error).not.toBeNull();
      expect(selectPosts(rootState).error).toEqual("Network request failed");
      done();
    });

    it("should update state when API call is successful", async (done) => {
      // Arrange
      const response: Post[] = [
        {
          userId: 1,
          id: 1,
          title:
            "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
          body:
            "quia et suscipit\nsuscipit recusandae consequuntur expedita et cum\nreprehenderit molestiae ut ut quas totam\nnostrum rerum est autem sunt rem eveniet architecto",
        },
        {
          userId: 1,
          id: 2,
          title: "qui est esse",
          body:
            "est rerum tempore vitae\nsequi sint nihil reprehenderit dolor beatae ea dolores neque\nfugiat blanditiis voluptate porro vel nihil molestiae ut reiciendis\nqui aperiam non debitis possimus qui neque nisi nulla",
        },
      ];
      // Act
      const nextState: PostsState = await fetchedPostsReducer(
        initalPostState,
        fetchSuccessful(response, "")
      );
      // Assert
      const rootState: RootState = { ...appState, fetchedPosts: nextState };
      expect(selectPosts(rootState).loading).toBeFalsy();
      expect(selectPosts(rootState).error).toBeNull();
      expect(selectPosts(rootState).posts).toEqual(
        expect.arrayContaining(response)
      );
      done();
    });
  });
});

Answer 1

我已经在 GitHub 上回答了 redux 工具包的问题，​​但我也会在这里发帖，因为这是我在尝试自己的解决方案之前访问的众多链接之一。
解释
由于createAsyncThunk返回一个函数供以后执行，您可以利用它来发挥自己的优势。无需麻烦地测试整个商店与您的 thunk 的交互，您可以在远离商店的情况下单独测试 thunk 本身。
运行您的jest.mock调用模拟您可能用来访问服务器或本地状态的任何 API/ Hook ，更改这些解析/返回的内容，然后执行您保存的方法。这样做可以让您访问 createAsyncThunk 中的 promise /方法。使用您通常会调用的参数进行调用。
具体问题
您不想测试商店，而是要测试 thunk 是否正在调度商店所依赖的操作来设置诸如加载、您要保存的错误消息等。这样您就可以为您的 reducer 创建测试，其中您可以在每次测试时重新创建一个全新的商店，并确保通过这些 reducer 进行的所有转换都是正确的。

通克

// features/account/thunks.ts

import api from './api';                    // http calls to the API
import { actions } from './reducer';        // "actions" from a createSlice result
import { useRefreshToken } from './hooks';  // a `useSelector(a => a.account).auth?.refreshToken` result

// declare and code as normal
export const register = createAsyncThunk(
  'accounts/register',
  async (arg: IRegisterProps, { dispatch }) => {
    try {
      const data = await api.register(arg);
      dispatch(actions.authSuccess(data));
    } catch (err) {
      console.error('Unable to register', err);
    }
  }
);

// Using a hook to access state
export const refreshSession = createAsyncThunk(
  'accounts/refreshSession',
  async (_, { dispatch }) => {
    // or add `, getState` beside dispatch and do token = getState().accounts.auth.refreshToken;
    // If you use getState, your test will be more verbose though
    const token: string = useRefreshToken();
    try {
      const data = await api.refreshToken(token);
      dispatch(actions.tokenRefreshed(data));
    } catch (err) {
      console.error('Unable to refresh token', err);
    }
  }
);

考试

// features/account/thunks.test.ts

import apiModule from './api';
import hookModule from './hooks';
import thunks from './thunks';

import { actions } from './reducer';
import { IRegisterProps } from './types';
import { AsyncThunkAction, Dispatch } from '@reduxjs/toolkit';
import { IAuthSuccess } from 'types/auth';

jest.mock('./api');
jest.mock('./hooks')

describe('Account Thunks', () => {
  let api: jest.Mocked<typeof apiModule>;
  let hooks: jest.Mocked<typeof hookModule>

  beforeAll(() => {
    api = apiModule as any;
    hooks = hookModule as any;
  });

  // Clean up after yourself.
  // Do you want bugs? Because that's how you get bugs.
  afterAll(() => {
    jest.unmock('./api');
    jest.unmock('./hooks');
  });

  describe('register', () => {

    // We're going to be using the same argument, so we're defining it here
    // The 3 types are <What's Returned, Argument, Thunk Config>
    let action: AsyncThunkAction<void, IRegisterProps, {}>;
    
    let dispatch: Dispatch;        // Create the "spy" properties
    let getState: () => unknown;

    let arg: IRegisterProps;
    let result: IAuthSuccess;

    beforeEach(() => {
      // initialize new spies
      dispatch = jest.fn();
      getState = jest.fn();

      api.register.mockClear();
      api.register.mockResolvedValue(result);

      arg = { email: 'me@myemail.com', password: 'yeetmageet123' };
      result = { accessToken: 'access token', refreshToken: 'refresh token' };

      action = thunks.registerNewAccount(arg);
    });

    // Test that our thunk is calling the API using the arguments we expect
    it('calls the api correctly', async () => {
      await action(dispatch, getState, undefined);
      expect(api.register).toHaveBeenCalledWith(arg);
    });

    // Confirm that a success dispatches an action that we anticipate
    it('triggers auth success', async () => {
      const call = actions.authSuccess(result);
      await action(dispatch, getState, undefined);
      expect(dispatch).toHaveBeenCalledWith(call);
    });
  });

  describe('refreshSession', () => {
    // We're going to be using the same argument, so we're defining it here
    // The 3 types are <What's Returned, Argument, Thunk Config>
    let action: AsyncThunkAction<void, unknown, {}>;
    
    let dispatch: Dispatch;        // Create the "spy" properties
    let getState: () => unknown;

    let result: IAuthSuccess;
    let existingToken: string;

    beforeEach(() => {
      // initialize new spies
      dispatch = jest.fn();
      getState = jest.fn();

      existingToken = 'access-token-1';

      hooks.useRefreshToken.mockReturnValue(existingToken);

      api.refreshToken.mockClear();
      api.refreshToken.mockResolvedValue(result);

      result = { accessToken: 'access token', refreshToken: 'refresh token 2' };

      action = thunks.refreshSession();
    });

    it('does not call the api if the access token is falsy', async () => {
      hooks.useRefreshToken.mockReturnValue(undefined);
      await action(dispatch, getState, undefined);
      expect(api.refreshToken).not.toHaveBeenCalled();
    });

    it('uses a hook to access the token', async () => {
      await action(dispatch, getState, undefined);
      expect(hooks.useRefreshToken).toHaveBeenCalled();
    });

    // Test that our thunk is calling the API using the arguments we expect
    it('calls the api correctly', async () => {
      await action(dispatch, getState, undefined);
      expect(api.refreshToken).toHaveBeenCalledWith(existingToken);
    });

    // Confirm a successful action that we anticipate has been dispatched too
    it('triggers auth success', async () => {
      const call = actions.tokenRefreshed(result);
      await action(dispatch, getState, undefined);
      expect(dispatch).toHaveBeenCalledWith(call);
    });
  });
});