Jest unit test error from mockAllIsIntersecting since installing intersection-observer

[Muzyar-rad]

Hi,

Do you know why I am getting this following error since installing npm i intersection-observer?

This is the error I receive when using mockAllIsIntersecting in my test:

TypeError: Cannot read property 'isIntersecting' of undefined

[thebuilder]

Can you post the full stack trace? Installing intersection-observer shouldn't have an impact. It's unsupported in Jest (and JSDom), so it should be mocked. The test-utils.js should do it automatically.

[Muzyar-rad]

I am using:

"react-intersection-observer": "^9.2.0",
 "intersection-observer": "^0.12.2"

[thebuilder]

Are you importing intersection-observer anywhere? It might break, since it skips mocking intersection observer if window.IntersectionObserver is defined.

[Muzyar-rad]

yes I am importing that actually. Since I am importing a parent package that in fact that package is doing -import intersection-observer.
What is my alternative? Can I still use your package with the line of code mentioned above?

[thebuilder]

You could try running setupIntersectionMocking(jest.fn) in your test.
This is normally run in beforeEach, and it replaces window.IntersectionObserver with a mocked version.

Maybe try logging out window.IntersectionObserver first, to determine if it is in fact a mocked version?

[Muzyar-rad]

yes you are right. setupIntersectionMocking(jest.fn) in beforeEach worked and it seems to start mocking the intersectionObserver. Now I am getting this error though:
TypeError: item.callback is not a function