react-testing | sample project from a talk on testing React | Frontend Framework library

I am testing an app with react-testing-library and I am using a mock service worker. All my tests pass until the last one which gives this error in the title. When testing only the part which gives error isolated (test.only), then it doesn't throw error. The error points to localhost:5000 which is my data server (my app is running on 3000)

This is my last test which only works when running alone:

I'm new to Jest and react-testing-library, so hopefully the solution to this is straight forward.

What is the proper way to test the value returned through the 'onChange' prop?

when i try to build my project with yarn run build i get errors that are not exist in my code my code is clean it works fine in my local. I've been stuck for two weeks to resolve this problem please help me to solve this problem. this the errors that i get

node version: v10.15.3

webpack: 4.30.0 this is my package.json

I'm using Jest/Enzyme to test a React/TypeScript application and I'm having a hard time trying to write a test to assert if a button shows up after a certain period of time:

Here's a very simplified version of the component to be tested:

Is there a way to fire a custom event with react-testing-library? I couldn't find such example in their docs.

How to mock video duration from fire event loadedMetadata with react-testing library?

in my React code, I'm retrieving the video duration with loadedMetaData event listener:

I have a material-ui navbar with a couple of material-ui icons on it. One of them is a Bookmarks icon. When clicking the icon it becomes blue (rgb(25, 118, 210)) and when it is clicked again or somewhere in the page it should become white. This is achieved using a local variable.

I've stucked when learning how to tests react components with custom hooks. I think that the issue is connected with hook mocking but I have no idea what I'm doing wrong. I'm using jest and react-testing-library.

counter.js

I'm trying to figure out how to test components that update state using useEffect to make an API call to get data. There are several things I think are important to know before I can talk anymore, and that is the files/packages I'm using.

First, I have a main component called App.tsx, inside App.tsx, inside of useEffect, I make a fetch call to an external API to fetch an array of songs by Queen. I also render out a component using .map to iterate over each song and .filter to filter songs on UI based on text input. I'm using a custom hook. Here is the code I have for that component and its custom hook.