Add some tests for earlyinit.fix_harfbuzz

See #1948

tests/unit/misc/test_earlyinit.py

@@ -19,7 +19,11 @@
 
 """Test qutebrowser.misc.earlyinit."""
 
+import os
 import sys
+import types
+import logging
+import pkg_resources
 
 import pytest
 
@@ -31,3 +35,76 @@ def test_init_faulthandler_stderr_none(monkeypatch, attr):
     """Make sure init_faulthandler works when sys.stderr/__stderr__ is None."""
     monkeypatch.setattr(sys, attr, None)
     earlyinit.init_faulthandler()
+
+
+class TestFixHarfbuzz:
+
+    @pytest.fixture(autouse=True)
+    def clear_harfbuzz(self):
+        """Clear QT_HARFBUZZ before/after tests."""
+        old_harfbuzz = os.environ.pop('QT_HARFBUZZ', None)
+        yield
+        if old_harfbuzz is None:
+            os.environ.pop('QT_HARFBUZZ', None)
+        else:
+            os.environ['QT_HARFBUZZ'] = old_harfbuzz
+
+    @pytest.fixture
+    def args(self):
+        """Get a fake argparse namespace."""
+        return types.SimpleNamespace(harfbuzz='auto')
+
+    @pytest.mark.parametrize('harfbuzz, qt_version, platform, expected', [
+        ('auto', '5.2.1', 'linux', 'old'),
+        ('auto', '5.3.0', 'linux', 'new'),
+        ('auto', '5.3.2', 'linux', 'old'),
+        ('auto', '5.4.0', 'linux', None),
+
+        ('auto', '5.2.1', 'windows', None),
+
+        ('old', '5.3.0', 'linux', 'old'),
+        ('old', '5.4.0', 'linux', 'old'),
+
+        ('new', '5.2.1', 'linux', 'new'),
+        ('new', '5.3.2', 'linux', 'new'),
+        ('new', '5.4.0', 'linux', 'new'),
+    ])
+    def test_fix_harfbuzz(self, clear_harfbuzz, args, monkeypatch, caplog,
+                          harfbuzz, qt_version, platform, expected):
+        """Check the QT_HARFBUZZ env var."""
+        args.harfbuzz = harfbuzz
+        monkeypatch.setattr(earlyinit, '_qt_version',
+                            lambda: pkg_resources.parse_version(qt_version))
+        monkeypatch.setattr(earlyinit.sys, 'platform', platform)
+
+        with caplog.at_level(logging.WARNING):
+            # Because QtWidgets is already imported
+            earlyinit.fix_harfbuzz(args)
+
+        assert os.environ.get('QT_HARFBUZZ', None) == expected
+
+    @pytest.mark.parametrize('frozen, level', [
+        (True, logging.DEBUG),
+        (False, logging.WARNING),
+    ])
+    def test_widgets_warning(self, args, monkeypatch, caplog, frozen, level):
+        """Make sure fix_harfbuzz warns when QtWidgets is imported."""
+        # Make sure QtWidgets is in sys.modules
+        from PyQt5 import QtWidgets  # pylint: disable=unused-variable
+        if frozen:
+            monkeypatch.setattr(earlyinit.sys, 'frozen', True, raising=False)
+        else:
+            monkeypatch.delattr(earlyinit.sys, 'frozen', raising=False)
+
+        with caplog.at_level(level):
+            earlyinit.fix_harfbuzz(args)
+
+        record = caplog.records[0]
+        assert record.levelno == level
+        msg = "Harfbuzz fix attempted but QtWidgets is already imported!"
+        assert record.message == msg
+
+    def test_no_warning(self, args, monkeypatch):
+        """Without QtWidgets in sys.modules, no warning should be shown."""
+        monkeypatch.setattr(earlyinit.sys, 'modules', {})
+        earlyinit.fix_harfbuzz(args)