These commands are more closely tied to the CompletionView than
Completer. This removes the need for an extra signal tying the
CompletionView to the Completer.
The call to _open_completion_if_needed was moved to
on_selection_changed, as this will already be called when a new item is
selected.
Rather than having a CompletionView instantiate and register a
Completer, instantiate both in MainWindow. The CompletionView is the
parent of the Completer, and communicates by emitting
selection_changed, meaning it no longer needs to contain a reference to
the Completer.
- clean up docstring typos
- use _ to name an unused loop variable
- parent the filter model to avoid an issue with disposal
- use mocker.patch instead of monkeypatch to mock Completer creation
- use is instead of == to compare by identity
