Re-add backend checks to new config

qutebrowser/config/config.py

@@ -29,6 +29,7 @@ from PyQt5.QtCore import pyqtSignal, pyqtSlot, QObject, QUrl
 from qutebrowser.config import configdata, configexc, configtypes, configfiles
 from qutebrowser.utils import (utils, objreg, message, standarddir, log,
                                usertypes, jinja)
+from qutebrowser.misc import objects
 from qutebrowser.commands import cmdexc, cmdutils, runners
 
 
@@ -303,11 +304,8 @@ class ConfigCommands:
         """Catch errors in set_command and raise CommandError."""
         try:
             yield
-        except (configexc.NoOptionError, configexc.ValidationError) as e:
-            raise cmdexc.CommandError("set: {}".format(e))
         except configexc.Error as e:
-            raise cmdexc.CommandError("set: {} - {}".format(
+            raise cmdexc.CommandError("set: {}".format(e))
-                e.__class__.__name__, e))
 
     @cmdutils.register(instance='config-commands', maxsplit=1,
                        no_cmd_split=True, no_replace_variables=True)
@@ -380,18 +378,25 @@ class Config(QObject):
         self._mutables = []
         self._yaml = yaml_config
 
-    def _changed(self, name, value):
+    def _set_value(self, opt, value):
-        """Emit changed signal and log change."""
+        """Set the given option to the given value."""
-        self.changed.emit(name)
+        if objects.backend is not None:
-        log.config.debug("Config option changed: {} = {}".format(name, value))
+            # FIXME:conf Validate all backends after init
+            if objects.backend not in opt.backends:
+                raise configexc.BackendError(objects.backend)
+
+        opt.typ.to_py(value)  # for validation
+        self._values[opt.name] = value
+
+        self.changed.emit(opt.name)
+        log.config.debug("Config option changed: {} = {}".format(
+            opt.name, value))
 
     def read_yaml(self):
         """Read the YAML settings from self._yaml."""
         self._yaml.load()
         for name, value in self._yaml.values.items():
-            opt = self.get_opt(name)
+            self._set_value(self.get_opt(name), value)
-            opt.typ.to_py(value)  # for validation
-            self._values[name] = value
         # FIXME:conf when to emit changed() here?
 
     def get_opt(self, name):
@@ -436,10 +441,7 @@ class Config(QObject):
 
         If save_yaml=True is given, store the new value to YAML.
         """
-        opt = self.get_opt(name)
+        self._set_value(self.get_opt(name), value)
-        opt.typ.to_py(value)  # for validation
-        self._values[name] = value
-        self._changed(name, value)
         if save_yaml:
             self._yaml.values[name] = value
 
@@ -450,8 +452,7 @@ class Config(QObject):
         """
         opt = self.get_opt(name)
         converted = opt.typ.from_str(value)
-        self._values[name] = converted
+        self._set_value(opt, converted)
-        self._changed(name, converted)
         if save_yaml:
             self._yaml.values[name] = converted
 

tests/unit/config/test_config.py

@@ -29,6 +29,7 @@ import qutebrowser.app  # To register commands
 from qutebrowser.commands import cmdexc
 from qutebrowser.config import config, configdata, configexc, configfiles
 from qutebrowser.utils import objreg, usertypes
+from qutebrowser.misc import objects
 
 
 @pytest.fixture(autouse=True)
@@ -292,12 +293,14 @@ class TestSetConfigCommand:
         assert msg.text == 'url.auto_search = never'
 
     @pytest.mark.parametrize('temp', [True, False])
-    def test_set_simple(self, commands, config_stub, temp):
+    def test_set_simple(self, monkeypatch, commands, config_stub, temp):
         """:set [-t] url.auto_search dns
 
         Should set the setting accordingly.
         """
+        monkeypatch.setattr(objects, 'backend', usertypes.Backend.QtWebKit)
         assert config_stub.val.url.auto_search == 'naive'
+
         commands.set(0, 'url.auto_search', 'dns', temp=temp)
 
         assert config_stub.val.url.auto_search == 'dns'
@@ -383,6 +386,13 @@ class TestSetConfigCommand:
                            "boolean!"):
             commands.set(0, 'auto_save.config', 'blah')
 
+    def test_set_wrong_backend(self, commands, monkeypatch):
+        monkeypatch.setattr(objects, 'backend', usertypes.Backend.QtWebEngine)
+        with pytest.raises(cmdexc.CommandError,
+                           match="set: This setting is not available with the "
+                           "QtWebEngine backend!"):
+            commands.set(0, 'content.cookies.accept', 'all')
+
     @pytest.mark.parametrize('option', ['?', '!', 'url.auto_search'])
     def test_empty(self, commands, option):
         """:set ? / :set ! / :set url.auto_search
@@ -572,12 +582,15 @@ class TestConfig:
         yaml_config = stubs.FakeYamlConfig()
         return config.Config(yaml_config)
 
-    def test_changed(self, qtbot, conf, caplog):
+    def test_set_value(self, qtbot, conf, caplog):
+        opt = conf.get_opt('tabs.show')
         with qtbot.wait_signal(conf.changed) as blocker:
-            conf._changed('foo', '42')
+            conf._set_value(opt, 'never')
-        assert blocker.args == ['foo']
+
+        assert blocker.args == ['tabs.show']
         assert len(caplog.records) == 1
-        assert caplog.records[0].message == 'Config option changed: foo = 42'
+        expected_message = 'Config option changed: tabs.show = never'
+        assert caplog.records[0].message == expected_message
 
     def test_read_yaml(self, conf):
         # FIXME:conf what about wrong values?
@@ -700,6 +713,15 @@ class TestConfig:
                 meth('content.plugins', '42')
         assert 'content.plugins' not in conf._values
 
+    @pytest.mark.parametrize('method', ['set_obj', 'set_str'])
+    def test_set_wrong_backend(self, conf, qtbot, monkeypatch, method):
+        monkeypatch.setattr(objects, 'backend', usertypes.Backend.QtWebEngine)
+        meth = getattr(conf, method)
+        with pytest.raises(configexc.BackendError):
+            with qtbot.assert_not_emitted(conf.changed):
+                meth('content.cookies.accept', 'all')
+        assert 'content.cookies.accept' not in conf._values
+
     def test_dump_userconfig(self, conf):
         conf.set_obj('content.plugins', True)
         conf.set_obj('content.headers.custom', {'X-Foo': 'bar'})