Update command completion on setting an alias.

Wire up the config change event to update command completion on
changing aliases, so the new aliases will be included.

Fixes #1814.

Currently we do not have tests at a high enough level to test whether
signals are wired up correctly to update completions.

qutebrowser/completion/models/instances.py

@@ -29,7 +29,7 @@ import functools
 
 from qutebrowser.completion.models import miscmodels, urlmodel, configmodel
 from qutebrowser.utils import objreg, usertypes, log, debug
-from qutebrowser.config import configdata
+from qutebrowser.config import configdata, config
 
 
 _instances = {}
@@ -155,6 +155,12 @@ def update(completions):
                 did_run.append(func)
 
 
+@config.change_filter('aliases', function=True)
+def _update_aliases():
+    """Update completions that include command aliases."""
+    update([usertypes.Completion.command])
+
+
 def init():
     """Initialize completions. Note this only connects signals."""
     quickmark_manager = objreg.get('quickmark-manager')
@@ -176,3 +182,5 @@ def init():
     keyconf = objreg.get('key-config')
     keyconf.changed.connect(
         functools.partial(update, [usertypes.Completion.command]))
+
+    objreg.get('config').changed.connect(_update_aliases)

tests/unit/config/test_config.py

@@ -214,7 +214,7 @@ class TestKeyConfigParser:
 
     """Test config.parsers.keyconf.KeyConfigParser."""
 
-    def test_cmd_binding(self, cmdline_test):
+    def test_cmd_binding(self, cmdline_test, config_stub):
         """Test various command bindings.
 
         See https://github.com/The-Compiler/qutebrowser/issues/615
@@ -222,6 +222,7 @@ class TestKeyConfigParser:
         Args:
             cmdline_test: A pytest fixture which provides testcases.
         """
+        config_stub.data = {'aliases': []}
         kcp = keyconf.KeyConfigParser(None, None)
         kcp._cur_section = 'normal'
         if cmdline_test.valid: