News Articles mocking

How to mock in Jest the on function

I would need some help to mock this part of code related to client?.on(‘error’, (errorCode, errorMessage) by using Jest. This is the full implementation: const useGeocomplyPlcWeb = () => { const dispatch = useDispatch() const [connected, setConnected] = useState(false) const [geoPacket, setGeopacket] = useState(”) const locationVerified = useSelector(state => state?.geocomply.location?.verified) const client = window?.GeoComply?.Client useLayoutEffect(() […]

In React, is there a good way to demo "connected components" in Storybook stories?

Connected Components In React, I really like writing “connected components” — where each component manages its own local state, data fetching, etc. For example, a high-level Search component could be built from an auto-completing SearchBar, a Results list, and a Recommendations section. Ideally, each of these sub-components manage their own state and data fetching. export […]

How to mock/configure dynamodb in EXPRESS API

I have decided to go with mocking dynamodb in my express API using jest. Checkedout out various examples aws-sdk-mock but what i am failing to understand is that -> "dynamodb operations code is inside express route and test file is seperate, so how do i write a mock which ensures that does testing express […]

How to reset a specific method of a module with resetAllMocks in Jest?

I’ve been researching for quite a while for this, none of the answers are solving the problem. I have resetAllMocks afterEach tests set. I want to mock a specific method of a module. If I: import * as ReactRouter from ‘react-router’; const mockPush = jest.fn(); jest.mock(‘react-router’, () => ({ …jest.requireActual(‘react-router’), useHistory: () => { return […]

VueJS + Vue Test Utils + Jes ; Cannot read property ‘token’ of undefined"

i try to make my test for a simple setting page with an axios call to get the member info (name, firstname, number …), im new on units tests. On my component, i start a function in my created() [Vue warn]: Error in created hook: "TypeError: Cannot read property ‘token’ of undefined" My "this.$globalData.token" is […]

How To Mock Chained MongoDB Function With Jest

I am trying to mock MongoClient’s insertMany functions. With this mock I won’t use real mongo db instead of it I will use mock implementation with Jest. However I am having an error like DbConnection.db(…).collection is not a function await DbConnection.db().collection(this.collectionName).insertMany(logs); Mock const DbConnection = { db: () => jest.fn().mockImplementationOnce(() =>({ collection: () => jest.fn().mockImplementationOnce(() […]

Trying to mock const doesn’t work in nodejs

I’ve been trying to mock method fetchFromCache in movie.js but not possible so far. I tried a lot of things but I think the way is written makes everything more complicated. I can’t change the code as there are a lot of things written this way and I’m adding unit tests now. Last thing I […]

How to mock the return value of a custom React hook using Jest?

I am aware there are similar questions to this on Stack Overflow, but no existing answers have been able to help me. I have tried many combination of jest.mock()/jest.fn() with no improvement. I am attempting to test a React component, Messenger, which imports and uses a custom hook, useWindowSize. The custom hook returns an object […]

How to test a class methods with no return statement?

I have a class with methods: class ProtoClass extends MainClass { {…} methodFirst(x, y) { const anotherClass = new AnotherClass() // I want to test the following line anotherClass.methodSecond(x) } {…} } The function methodFirst has no return value. I want to test the following cases: methodFirst was called with correct arguments Inside methodFirst another […]

Best practice replace URL during build step of npm

I’ve a mock REST service during development and a real backend I want to use for the public release. Is there a way to replace the endpoint URL somehow during the npm build step? What is the best practice? Source: JavaSript – Stack Overflow

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Senior Software Developer

Creator of @LzoMedia I am a backend software developer based in London who likes beautiful code and has an adherence to standards & love's open-source.