lint: add stacklevel kwarg to warnings

flake8-bugbear B028 No explicit stacklevel keyword argument found. The
warn method from the warnings module uses a stacklevel of 1 by default.
This will only show a stack trace for the line on which the warn method
is called. It is therefore recommended to use a stacklevel of 2 or
greater to provide more information to the user.

Semgrep helped:

    semgrep --lang=py -e 'warnings.warn($ARG)' --replacement 'warnings.warn($ARG, stacklevel=2)' $FILES -a
    semgrep --lang=py -e 'warnings.warn($ARG1, $ARG2)' --replacement 'warnings.warn($ARG1, $ARG2, stacklevel=2)' $FILES -a

Although it did lose the f-string on one of them.

4 files changed, 10 insertions, 10 deletions

diff --git a/tests/end2end/fixtures/testprocess.py b/tests/end2end/fixtures/testprocess.py
index 96e700390..9276a4820 100644
--- a/tests/end2end/fixtures/testprocess.py
+++ b/tests/end2end/fixtures/testprocess.py
@@ -319,7 +319,7 @@ class Process(QObject):
         if not ok:
             cmdline = ' '.join([self.proc.program()] + self.proc.arguments())
             warnings.warn(f"Test process {cmdline} with PID {self.proc.processId()} "
-                          "failed to terminate!")
+                          "failed to terminate!", stacklevel=2)
             self.proc.kill()
             self.proc.waitForFinished()
 
diff --git a/tests/test_conftest.py b/tests/test_conftest.py
index fedc6b43f..2019bfd0b 100644
--- a/tests/test_conftest.py
+++ b/tests/test_conftest.py
@@ -41,7 +41,7 @@ def test_no_qapp(request):
 
 def test_fail_on_warnings():
     with pytest.raises(PendingDeprecationWarning):
-        warnings.warn('test', PendingDeprecationWarning)
+        warnings.warn('test', PendingDeprecationWarning, stacklevel=2)
 
 
 @pytest.mark.xfail(reason="https://github.com/qutebrowser/qutebrowser/issues/1070",
diff --git a/tests/unit/config/test_configtypes.py b/tests/unit/config/test_configtypes.py
index 99b8a5de0..22ac3e9df 100644
--- a/tests/unit/config/test_configtypes.py
+++ b/tests/unit/config/test_configtypes.py
@@ -1521,7 +1521,7 @@ class TestRegex:
         """
         regex = klass()
         m = mocker.patch('qutebrowser.config.configtypes.re')
-        m.compile.side_effect = lambda *args: warnings.warn(warning)
+        m.compile.side_effect = lambda *args: warnings.warn(warning, stacklevel=2)
         m.error = re.error
         with pytest.raises(type(warning)):
             regex.to_py('foo')
diff --git a/tests/unit/utils/test_log.py b/tests/unit/utils/test_log.py
index bbc6b02db..0a03ea7ee 100644
--- a/tests/unit/utils/test_log.py
+++ b/tests/unit/utils/test_log.py
@@ -275,7 +275,7 @@ class TestInitLog:
         log.init_log(args)
 
         with caplog.at_level(logging.WARNING):
-            warnings.warn("test warning", PendingDeprecationWarning)
+            warnings.warn("test warning", PendingDeprecationWarning, stacklevel=2)
 
         expected = "PendingDeprecationWarning: test warning"
         assert expected in caplog.records[0].message
@@ -285,7 +285,7 @@ class TestInitLog:
         log.init_log(args)
 
         with pytest.raises(PendingDeprecationWarning):
-            warnings.warn("test warning", PendingDeprecationWarning)
+            warnings.warn("test warning", PendingDeprecationWarning, stacklevel=2)
 
     @pytest.mark.parametrize('cli, conf, expected', [
         (None, 'info', logging.INFO),
@@ -386,9 +386,9 @@ def test_stub(caplog, suffix, expected):
 def test_py_warning_filter(caplog):
     logging.captureWarnings(True)
     with log.py_warning_filter(category=UserWarning):
-        warnings.warn("hidden", UserWarning)
+        warnings.warn("hidden", UserWarning, stacklevel=2)
     with caplog.at_level(logging.WARNING):
-        warnings.warn("not hidden", UserWarning)
+        warnings.warn("not hidden", UserWarning, stacklevel=2)
     assert len(caplog.records) == 1
     msg = caplog.messages[0].splitlines()[0]
     assert msg.endswith("UserWarning: not hidden")
@@ -396,17 +396,17 @@ def test_py_warning_filter(caplog):
 
 def test_py_warning_filter_error(caplog):
     warnings.simplefilter('ignore')
-    warnings.warn("hidden", UserWarning)
+    warnings.warn("hidden", UserWarning, stacklevel=2)
 
     with log.py_warning_filter('error'):
         with pytest.raises(UserWarning):
-            warnings.warn("error", UserWarning)
+            warnings.warn("error", UserWarning, stacklevel=2)
 
 
 def test_warning_still_errors():
     # Mainly a sanity check after the tests messing with warnings above.
     with pytest.raises(UserWarning):
-        warnings.warn("error", UserWarning)
+        warnings.warn("error", UserWarning, stacklevel=2)
 
 
 class TestQtMessageHandler: