How to mock `distinctUntilChanged` in an angular app

[tomavic]

Is your feature request related to a problem? Please describe.
I need to mock the following:

  getListOfItems() {
    // When Filter or Language changes
    return merge(
      this.translate.onLangChange,
      this.storeService.filtration$.pipe(
        distinctUntilChanged(
          (prev, curr) =>
            prev.searchKey === curr.searchKey &&
            prev.pageNumber === curr.pageNumber &&
            prev.pageSize === curr.pageSize &&
            prev.filterKey === curr.filterKey
        )
      )
    ).pipe(switchMap(() => this.getBundlesList()));
  }

Additional context
Angular app

[hlovdal]

This is rather unclear. If you are testing the getListOfItems function, the normal thing to do is to provide mock implementations of translate and storeService which you configure to return what you want.

Just use distinctUntilChanged directly as is, it makes no sense to trying to alter/replace it in any way.