Remove unknown YAML data from config

I considered introducing another list of deleted options (or a "deleted: True"
in configdata.yml), similar to what we had with the old config.

However, let's take the easier route and just delete everything we don't know
from configdata.yml. If someone edits it by hand, it's their fault :P

See #2772, #2847

qutebrowser/config/configfiles.py

@@ -30,7 +30,7 @@ import yaml
 from PyQt5.QtCore import QSettings
 
 import qutebrowser
-from qutebrowser.config import configexc, config
+from qutebrowser.config import configexc, config, configdata
 from qutebrowser.utils import standarddir, utils, qtutils
 
 
@@ -153,6 +153,12 @@ class YamlConfig:
                 "'global' object is not a dict")
             raise configexc.ConfigFileErrors('autoconfig.yml', [desc])
 
+        # Delete unknown values
+        # (e.g. options which were removed from configdata.yml)
+        for name in list(global_obj):
+            if name not in configdata.DATA:
+                del global_obj[name]
+
         self._values = global_obj
         self._dirty = False
 

tests/unit/config/test_config.py

@@ -932,14 +932,9 @@ def test_early_init(init_patch, config_tmpdir, caplog, fake_args,
         expected_errors.append(
             "Errors occurred while reading config.py:\n"
             "  While setting 'foo': No option 'foo'")
-    if invalid_yaml and (load_autoconfig or not config_py):
+    if invalid_yaml == '42' and (load_autoconfig or not config_py):
         error = "Errors occurred while reading autoconfig.yml:\n"
-        if invalid_yaml == '42':
-            error += "  While loading data: Toplevel object is not a dict"
-        elif invalid_yaml == 'unknown':
-            error += "  Error: No option 'colors.foobar'"
-        else:
-            assert False, invalid_yaml
+        error += "  While loading data: Toplevel object is not a dict"
         expected_errors.append(error)
 
     actual_errors = [str(err) for err in config._init_errors]

tests/unit/config/test_configfiles.py

@@ -57,6 +57,8 @@ def test_state_config(fake_save_manager, data_tmpdir,
 @pytest.mark.parametrize('old_config', [
     None,
     'global:\n  colors.hints.fg: magenta',
+    # Unknown key
+    'global:\n  hello: world',
 ])
 @pytest.mark.parametrize('insert', [True, False])
 def test_yaml_config(fake_save_manager, config_tmpdir, old_config, insert):
@@ -91,6 +93,7 @@ def test_yaml_config(fake_save_manager, config_tmpdir, old_config, insert):
         assert '  colors.hints.fg: magenta' in lines
     if insert:
         assert '  tabs.show: never' in lines
+    assert '  hello:' not in lines
 
 
 @pytest.mark.parametrize('old_config', [