Meta:
https://meta.discourse.org/t/cant-erase-the-bookmark-search-input/357861/4
> When we fill in the bookmark search input and send the request, then
we can’t delete the input’s content.
After removing the last character, the `searchTerm` getter is called. At
this point, `_searchTerm` is empty.
However, `this._searchTerm || this.q` will treat the empty string as
_falsy_, and the `q` value is displayed instead.
It makes it impossible to clear the input.
To fix this, we check specifically on the initial state of
`_searchTerm,` which is _undefined_, to include an empty string as a
valid value.
Note: because of `@computed`, the issue is not triggered when the
content is selected and deleted.
We were not updating `searchTerm` when changing the input which was making us always send an empty q parameter.
This commit is also adding tests for:
- initial url with q param
- filtering the bookmarks through the input
