I am running tests with jest and enzyme in my React application, and while my simple sanity check test (2+2 expect 4) works, this error is thrown when I go to shallow render a component. It also throws when I try to replace shallow() with render() Here is the app.test.js file: babel.config.js: EDIT : I added …
Tag: jestjs
What is the proper way to test Vue3 async setup component with suspense?
No doubt that Suspense feature leads to a cleaner code base, but as tidy as it is, it turns to be hard to test. Specifically it is not well documented yet. case: Regular app generated by VUE CLI Tech stack: Vuex, Router, PWA, jest for unit testing Challenge: I made use of Suspense component as recommended as …
jest ReferenceError: Cannot access ” before initialization
I’m getting the error: ReferenceError: Cannot access ‘myMock’ before initialization Even though i respected jest documentation about the hoisting: A limitation with the factory parameter is that, since calls to jest.mock() are hoisted to the top of the file, it’s not possible to first …
Testing Cross Browser Extension With Jest, How To Mock Chrome Storage API?
After putting off testing for a while now due to Cypress not allowing visiting chrome:// urls, I decided to finally understand how to unit/integration test my extension – TabMerger. This comes after the many times that I had to manually test the ever growing functionality and in some cases forgot to che…
JEST | Assert a function was called inside addEventListener callback
I have the following function: Code to test The question is: How can I assert using Jest that createAndAppendPTag was called upon a document click event ? Jest This is what I tried, but can’t seem to make the test pass: Terminal This results in the following: Thanks in advance. Answer I ran this simplif…
Jest: How to undo a global mock for certain tests in a file
I want to mock Math.random for certain tests and use its original implementation for other tests. How can I achieve this? I’ve read about using jest.doMock and jest.dontMock, but I’ve bumped into a number of issues using them, like: I seem to need require in order to use doMock and dontMock, but m…
Unit test with react hook fails
I don’t understand the result I get on this unit test. I expect the second check for textField.valid to be true and instead it returns false. Below is part of the component I’m testing against: … Below is the test I’m running: The output of console.log(wrapper.debug()) is the following…
Jest: TypeError: replaceAll is not a function
String.prototype.replaceAll() is a useful method and while building and executing everything works fine. However, all Jest-tests fail with the following error: These are my dependencies: How can I fix this behavior? Answer The problem This happens because replaceAll is a new function not implemented in all br…
Mocking dayjs extend
In my code that needs testing I use In my test I need to mock dayjs in order to always have the same date when comparing snapshots in jest so I did It fails with Unfortunately similar questions on here didn’t help me. How could I mock both default dayjs but also extend? Answer You could write a more tho…
Trouble finding Jest on Windows
I recently started off with some project over JavaScript, following some documentation. I am supposed to be using Jest for testing purposes. The installation of Jest seems pretty straightforward on Linux using npm: However, I am on Windows, and unable to find Jest over lets using NuGet. How can I retrieve Jes…