Simplify and reorganize configfile tests

Also make save/load of sys.path a little more robust

qutebrowser/config/configfiles.py

@@ -247,7 +247,7 @@ def read_config_py(filename=None):
         raise configexc.ConfigFileErrors(basename, [desc])
     except SyntaxError as e:
         desc = configexc.ConfigErrorDesc("Syntax Error", e,
-                                        traceback=traceback.format_exc())
+                                         traceback=traceback.format_exc())
         raise configexc.ConfigFileErrors(basename, [desc])
 
     try:
@@ -257,13 +257,14 @@ def read_config_py(filename=None):
             # other files in logical places
             config_dir = os.path.dirname(filename)
             if config_dir not in sys.path:
-                sys.path = [config_dir] + sys.path
+                sys.path.insert(0, config_dir)
 
             exec(code, module.__dict__)
     except Exception as e:
         api.errors.append(configexc.ConfigErrorDesc(
             "Unhandled exception",
             exception=e, traceback=traceback.format_exc()))
+
     api.finalize()
     return api
 
@@ -271,13 +272,11 @@ def read_config_py(filename=None):
 @contextlib.contextmanager
 def saved_sys_properties():
     """Save various sys properties such as sys.path and sys.modules."""
-    old_path = sys.path
+    old_path = sys.path.copy()
     old_modules = sys.modules.copy()
 
     try:
         yield
-    except:
-        raise
     finally:
         sys.path = old_path
         for module in set(sys.modules).difference(old_modules):

tests/unit/config/test_configfiles.py

@@ -19,6 +19,7 @@
 """Tests for qutebrowser.config.configfiles."""
 
 import os
+import sys
 
 import pytest
 
@@ -207,17 +208,39 @@ class TestYaml:
         assert error.traceback is None
 
 
+class ConfPy:
+
+    """Helper class to get a confpy fixture."""
+
+    def __init__(self, tmpdir, filename: str = "config.py"):
+        self._file = tmpdir / filename
+        self.filename = str(self._file)
+
+    def write(self, *lines):
+        text = '\n'.join(lines)
+        self._file.write_text(text, 'utf-8', ensure=True)
+
+    def read(self):
+        """Read the config.py via configfiles and check for errors."""
+        api = configfiles.read_config_py(self.filename)
+        assert not api.errors
+
+    def write_qbmodule(self):
+        self.write('import qbmodule',
+                   'qbmodule.run(config)')
+
+
 class TestConfigPyModules:
 
     pytestmark = pytest.mark.usefixtures('config_stub', 'key_config_stub')
 
     @pytest.fixture
     def confpy(self, tmpdir):
-        return TestConfigPy.ConfPy(tmpdir)
+        return ConfPy(tmpdir)
 
     @pytest.fixture
     def qbmodulepy(self, tmpdir):
-        return TestConfigPy.ConfPy(tmpdir, filename="qbmodule.py")
+        return ConfPy(tmpdir, filename="qbmodule.py")
 
     @pytest.fixture(autouse=True)
     def restore_sys_path(self):
@@ -279,30 +302,9 @@ class TestConfigPy:
 
     pytestmark = pytest.mark.usefixtures('config_stub', 'key_config_stub')
 
-    class ConfPy:
-
-        """Helper class to get a confpy fixture."""
-
-        def __init__(self, tmpdir, filename: str = "config.py"):
-            self._confpy = tmpdir / filename
-            self.filename = str(self._confpy)
-
-        def write(self, *lines):
-            text = '\n'.join(lines)
-            self._confpy.write_text(text, 'utf-8', ensure=True)
-
-        def read(self):
-            """Read the config.py via configfiles and check for errors."""
-            api = configfiles.read_config_py(self.filename)
-            assert not api.errors
-
-        def write_qbmodule(self):
-            self.write('import qbmodule',
-                       'qbmodule.run(config)')
-
     @pytest.fixture
     def confpy(self, tmpdir):
-        return self.ConfPy(tmpdir)
+        return ConfPy(tmpdir)
 
     @pytest.mark.parametrize('line', [
         'c.colors.hints.bg = "red"',