I have a simple function that calls my s3 service which will return a Promise I would like to mock the return of the object and assert it in the test like this: When i run the test, I face this error: Error [ERR_METHOD_NOT_IMPLEMENTED]: The _read() method is not implemented at Readable.read (internal/streams/…
Tag: jestjs
Is it is possible to test only one function from component with Jest?
I have react component, for example something like this: And I’m trying to write test that should looks like this: Can I mock useState, useContext and useLocation from <MyComponent/> and pass my custom data instead of real data from real component? Answer After deeper researching I’ve unders…
JEST – check if objects array is a subset of another array
Using JEST I want to test if an array of objects is a subset of another array. I want to test the following: I’ve tried the following: But this is not correct since objectContaining doesn’t accept array as param … it works only if subset is a single object. Answer I’ve never tried this…
How to test custom JavaScript Github actions?
I want to create a JavaScript Github action and use Jest for testing purposes. Based on the docs I started parsing the input, given the following example code Running this code during development throws the following error Input required and not supplied: my-key as expected because the code is not running ins…
Jest: Failed prop type: Invalid prop `source` supplied to `Image`, expected one of type [number]
I am using jest with react-native to run unit test cases. And whenever it encounters Image it throws the following warning I tried to replace the code to as suggested in https://stackoverflow.com/a/36460928/3855179 but it started throwing the following warning and the application breaks Any idea how this can …
Module pattern variable returning undefined in test?
I have the following code below which returns certain data depending on NODE_ENV: config.js This works well in my component when I set NODE_ENV. However in my test, I keep getting undefined as a result. config.test.js Again, Config.data works fine in my React component when I start it up, but I guess I need t…
Testing window.location in jest
I am trying to test the window functionality via jest. I have a function which appends a query param to the url and redirects the page to the other page. A rough snippet of the code is below: I am new to jest and I am facing a bit of difficulty simulating the mock test for this, hence can you
Node.js and Jest: Testing promise loop, count how many times function has been called
I want to test my code using JEST, but I’m having some issues. I want to check, if restart() function has been called. My code works like this, it’s waiting for the data, and if there’s no data it’s calling the same function again. Basically something like a loop. myCode.js file: myCod…
Issue with setting up jest mock
I have the following function that is used within cypress tests for which I want to do unit testing (filterTests.js): A test double for Cypress.env needs to be created. I’m not sure if this would technically be considered a stub, mock, fake, dummy, etc…, but the philosophical discussion isn’…
react – how to test a component if it has value prop
App.js Input.js I want to use jest and react-testing-library to test for the <Input> component. But I cannot figure out how to handle the value prop. This is the test file I’ve made, but I cannot go further. The test returns failed after I run it. Codesandbox https://codesandbox.io/s/affectionate-…