The `ScrollService` sets up some global `window` listeners.
Previously, these listeners were never unregistered. This was not a
problem in the real app, because the `ScrollService` instance exists for
the lifetime of a user session. In tests, however, where the `window`
instance is among all tests, the listeners would survive the
`ScrollService` tests. This, in addition to the fact that we used a mock
`ViewportScroller` which did not return the expected type from
`getScrollPosition()`, caused errors to be thrown in unrelated tests
(i.e. whenever a scroll event was emitted on `window`). See [here][1]
for an example failure.
This commit fixes it by adding an `ngOnDestroy()` method that
unregisters the listeners and ensuring it is called after each
`ScrollService` test.
[1]: https://circleci.com/gh/angular/angular/381649
PR Close#31390
Want to file a bug, contribute some code, or improve documentation? Excellent! Read up on our
guidelines for contributing and then check out one of our issues in the hotlist: community-help.
0c00c94f34
