Only apply blink-settings on Qt 15.5.2

Turns out Qt 5.15.{0,1} also needs `--force-dark-mode`. This commit
fixes it to only use the blink-setting on Qt 5.15.2 and up. It also
parameterizes the tests better to test that the settings work on their
respective Qt versions.

(cherry picked from commit 1f67527662a076aa0a3caf5348f9ba6b663f4a0e)

3 files changed, 27 insertions, 17 deletions

diff --git a/qutebrowser/config/qtargs.py b/qutebrowser/config/qtargs.py
index b42484a08..0afea7196 100644
--- a/qutebrowser/config/qtargs.py
+++ b/qutebrowser/config/qtargs.py
@@ -79,8 +79,10 @@ def _darkmode_prefix() -> str:
 
 def _darkmode_settings() -> typing.Iterator[typing.Tuple[str, str]]:
     """Get necessary blink settings to configure dark mode for QtWebEngine."""
-    if (qtutils.version_check('5.15', compiled=False) and
+    if (qtutils.version_check('5.15.2', compiled=False) and
             config.val.colors.webpage.prefers_color_scheme_dark):
+        # In future versions of 'blink', (> Qt 5.15.2) the enumeration has
+        # changed and this will need to be set to '0' instead.
         yield "preferredColorScheme", "1"
 
     if not config.val.colors.webpage.darkmode.enabled:
@@ -335,10 +337,10 @@ def _qtwebengine_settings_args() -> typing.Iterator[str]:
         }
 
     if (qtutils.version_check('5.14', compiled=False) and
-            not qtutils.version_check('5.15', compiled=False)):
-        # In Qt 5.14, `--force-dark-mode` is used to set the preferred
-        # colorscheme. In Qt 5.15, this is handled by a blink-setting
-        # instead.
+            not qtutils.version_check('5.15.2', compiled=False)):
+        # In Qt 5.14 to 5.15.1, `--force-dark-mode` is used to set the
+        # preferred colorscheme. In Qt 5.15.2, this is handled by a
+        # blink-setting instead.
         settings['colors.webpage.prefers_color_scheme_dark'] = {
             True: '--force-dark-mode',
             False: None,
diff --git a/tests/helpers/utils.py b/tests/helpers/utils.py
index 64779dfc6..46787391d 100644
--- a/tests/helpers/utils.py
+++ b/tests/helpers/utils.py
@@ -52,9 +52,6 @@ qt514 = pytest.mark.skipif(
 skip_qt511 = pytest.mark.skipif(
     qtutils.version_check('5.11'), reason="Needs Qt 5.10 or earlier")
 
-qt515 = pytest.mark.skipif(
-    not qtutils.version_check('5.15'), reason="Needs Qt 5.15 or newer")
-
 
 class PartialCompareOutcome:
 
diff --git a/tests/unit/config/test_qtargs.py b/tests/unit/config/test_qtargs.py
index 644765a58..782444da6 100644
--- a/tests/unit/config/test_qtargs.py
+++ b/tests/unit/config/test_qtargs.py
@@ -320,10 +320,14 @@ class TestQtArgs:
     @pytest.mark.parametrize('dark, qt_version, added', [
         (True, "5.13", False),
         (True, "5.14", True),
-        (True, "5.15", False),
+        (True, "5.15.0", True),
+        (True, "5.15.1", True),
+        (True, "5.15.2", False),
         (False, "5.13", False),
         (False, "5.14", False),
-        (False, "5.15", False),
+        (False, "5.15.0", False),
+        (False, "5.15.1", False),
+        (False, "5.15.2", False),
     ])
     @utils.qt514
     def test_prefers_color_scheme_dark(self, config_stub, monkeypatch, parser,
@@ -591,17 +595,24 @@ class TestDarkMode:
             assert opt.restart, name
             assert opt.raw_backends == backends, name
 
-    @pytest.mark.parametrize('enabled, expected', [
+    @pytest.mark.parametrize('qversion, enabled, expected', [
         # Disabled or nothing set
-        (False, []),
+        ("5.14", False, []),
+        ("5.15.0", False, []),
+        ("5.15.1", False, []),
+        ("5.15.2", False, []),
 
         # Enabled in configuration
-        (True, [("preferredColorScheme", "1")]),
+        ("5.14", True, []),
+        ("5.15.0", True, []),
+        ("5.15.1", True, []),
+        ("5.15.2", True, [("preferredColorScheme", "1")]),
     ])
-    @utils.qt515
-    def test_colorscheme(self, config_stub, monkeypatch, enabled, expected):
-        config_stub.set_obj('colors.webpage.prefers_color_scheme_dark', enabled)
-        assert list(qtargs._darkmode_settings()) == expected
+    @utils.qt514
+    def test_colorscheme(self, config_stub, monkeypatch, qversion, enabled, expected):
+        monkeypatch.setattr(qtargs.qtutils, 'qVersion', lambda: qversion)
+        config_stub.val.colors.webpage.prefers_color_scheme_dark = enabled
+        assert list(qtargs._dark_mode_settings()) == expected
 
 
 class TestEnvVars: