jest-test | Test repository to test jest mocking | Unit Testing library

In general, you can extend expect to add the matching behaviour you want, there are lots of examples in jest-extended. For this case, perhaps using the tools available in path to test against the appropriate path for whatever OS the tests are running on:

Actually to sum it up, what you're trying to test is not related to hooks if the hook is passed this into the child. Think of the child as your subject under test; in other words its the only thing you're trying to test. The "hook" by definition is irrelevant. You pass in a function and you can assert that a function that has been called with the proper value.

Which to sum it up, you have two cases

1. When the modal is open and you click on the button "Click to close modal" button, the modal will close or otherwise known is calling your mock function with false.
2. When the modal is closed and you click on the button "Click to close modal" button, the modal will open or otherwise known is calling your mock function with true.

I made minor edits to the test that you have above to demonstrate this. Feel free to copy and paste it in and check for yourself and let me know if you have questions.

Note: Copied and pasted from the sandbox link with minor modifications to not diverge too much from the original code.

You can use the getter and setter of the Object.defineProperty() method to intercept the assignment operation of the onload function, so you can get the onload function to test it as usual.

E.g.

index.js:

The first two tests fail because you're not using renderProp here. The second two tests fail because renderProp (docs) takes a prop name and returns a function that takes the render-prop arguments, so you'll need to pass the object in a separate function application:

As @jonrsharpe pointed out in the comments, I was assuming that with module.exports I export the app itself, but in fact I export an object containing the app. Therefore to fix the test error, I had to simply write in my test.js:

This is because you are exporting object instead of class. So the mocking is not working. You can use javascript feature of overwriting function, object and class manually (which is internally used by jest). The test code will look like this

If you are using Async/Await, then no need to use then()

I guess if the register failed, it would throw an error. So put the test code in error catching part.

This most likely happens because String.prototype.replaceAll is not implemented in node.js (At least as of version v14.15.0)

If the error occurs in your own code, one alternative you could use are regular expressions, like in this example:

Finally I could manage to make this work the following way: