Redux-Saga failing error handling tests using Generator.prototype.next()

Question

I am visiting an old project and ran the tests. However, testing my Redux-Saga is not passing its error handling tests.

All The other tests are passing without problem so I know the functions are being called correctly. Below is the test file

import { takeLatest, call, put } from 'redux-saga/effects'
    
import { firestore, convertCollectionsSnapshotToMap } from '../../firebase/firebase.utils'

import { fetchCollectionsSuccess, fetchCollectionsFailure } from './shop.actions'

import ShopActionTypes from './shop.types'

import { fetchCollectionsAsync, fetchCollectionsStart } from './shop.sagas'

describe('fetch collections start saga', () => {
    it('should trigger on FETCH_COLLECTIONS_START', () => {
        const generator = fetchCollectionsStart()
        expect(generator.next().value).toEqual(
            takeLatest(ShopActionTypes.FETCH_COLLECTIONS_START, fetchCollectionsAsync)
        )
    })
})

describe('fetch collections async saga', () => {
    const generator = fetchCollectionsAsync()

    it('should call firestore collection ', () => {
        const getCollection = jest.spyOn(firestore, 'collection')
        generator.next()
        expect(getCollection).toHaveBeenCalled()
    })

    it('should call convertCollectionsSnapshot saga ', () => {
        const mockSnapshot = {}
        expect(generator.next(mockSnapshot).value).toEqual(
            call(convertCollectionsSnapshotToMap, mockSnapshot)
        )
    })

    it('should fire fetchCollectionsSuccess if collectionsMap is succesful', () => {
        const mockCollectionsMap = {
            hats: { id: 1 }
        }

        expect(generator.next(mockCollectionsMap).value).toEqual(
            put(fetchCollectionsSuccess(mockCollectionsMap))
        )
    })

    // THIS IS THE FAILING CODE
    it('should fire fetchCollectionsFailure if get collection fails at any point', () => {
        const newGenerator = fetchCollectionsAsync()
        newGenerator.next()
        expect(newGenerator.throw({ message: 'error' }).value).toEqual(
            put(fetchCollectionsFailure('error'))
        )
    })
})

Below is my shop Saga.js file

import { takeLatest, call, put, all } from 'redux-saga/effects'

import { firestore, convertCollectionsSnapshotToMap } from '../../firebase/firebase.utils'

import { fetchCollectionsSuccess, fetchCollectionsFailure } from './shop.actions'

import ShopActionTypes from './shop.types'

export function* fetchCollectionsAsync() {
    try {
        const collectionRef = firestore.collection('collections')
        const snapshot = yield collectionRef.get()
        const collectionsMap = yield call(convertCollectionsSnapshotToMap, snapshot)
        yield put(fetchCollectionsSuccess(collectionsMap))
    } catch (error) {
        yield put(fetchCollectionsFailure(error.message))
    }
}

export function* fetchCollectionsStart() {
    yield takeLatest(ShopActionTypes.FETCH_COLLECTIONS_START, fetchCollectionsAsync)
}

export function* shopSagas() {
    yield all([call(fetchCollectionsStart)])
}

I have tried mocking the error and passing it into my tests also but I am getting the same output in my tests below, no matter how I refactor the code.

 PASS  src/pages/checkout/checkout.test.js
 FAIL  src/redux/shop/shop.sagas.test.js
  ● fetch collections async saga › should fire fetchCollectionsFailure if get collection fails at any point

    error



Test Suites: 1 failed, 1 passed, 2 total
Tests:       1 failed, 5 passed, 6 total
Snapshots:   1 passed, 1 total
Time:        3.076 s
Ran all test suites related to changed files

If anyone has any advice on where to look and how to fix this, it would be greatly appreciated. Thanks in advance

user_10097909 · Answer

I have written the following code as a workaround. Tests are now passing and the fetchCollectionsFailure is being called. It's not the prettiest code but it's a workaround and fulfills the criteria for now.

it('should fire fetchCollectionsFailure if get collection fails at any point', () => {
        const newGenerator = fetchCollectionsAsync()
        const error = {
            '@@redux-saga/IO': true,
            combinator: false,
            payload: {
                action: {
                    payload: "Cannot read property 'get' of undefined",
                    type: 'FETCH_COLLECTIONS_FAILURE'
                },
                channel: undefined
            },
            type: 'PUT'
        }
        expect(newGenerator.next().value).toMatchObject(error)
    })

Redux-Saga failing error handling tests using Generator.prototype.next()

1 Answers