Qt 6.9: Only disable software rendering for darkmode tests

Looks like the "tests hanging" issue was fixed between Beta 3 and RC.

See #8444

pytest.ini

@@ -80,8 +80,9 @@ qt_log_ignore =
     QItemSelectionModel: Selecting when no model has been set will result in a no-op.
     ^QSaveFile::commit: File \(.*[/\\]test_failing_flush0[/\\]foo\) is not open$
     ^The following paths were searched for Qt WebEngine dictionaries:.*
-    # Qt 6.9 Beta 1-3 with Xvfb
+    # Qt 6.9 with Xvfb
     ^Backend texture is not a Vulkan texture\.$
+    ^Compositor returned null texture$
     # With offscreen platform plugin
     ^This plugin does not support (raise\(\)|propagateSizeHints\(\)|createPlatformVulkanInstance|grabbing the keyboard)$
     ^QRhiGles2: Failed to create (temporary )?context$

tests/end2end/test_invocations.py

@@ -515,6 +515,10 @@ def test_preferred_colorscheme_with_dark_mode(
         '-s', 'colors.webpage.darkmode.enabled', 'true',
         '-s', 'colors.webpage.darkmode.algorithm', 'brightness-rgb',
     ]
+    if webengine_versions.webengine == utils.VersionNumber(6, 9):
+        # WORKAROUND: For unknown reasons, dark mode colors are wrong with
+        # Qt 6.9 + hardware rendering + Xvfb.
+        args += testutils.SOFTWARE_RENDERING_ARGS
     quteproc_new.start(args)
 
     quteproc_new.open_path('data/darkmode/prefers-color-scheme.html')
@@ -741,10 +745,13 @@ def test_dark_mode(webengine_versions, quteproc_new, request,
         '-s', 'colors.webpage.darkmode.enabled', 'true',
         '-s', 'colors.webpage.darkmode.algorithm', algorithm,
     ]
-    quteproc_new.start(args)
+    if webengine_versions.webengine == utils.VersionNumber(6, 9):
+        # WORKAROUND: For unknown reasons, dark mode colors are wrong with
+        # Qt 6.9 + hardware rendering + Xvfb.
+        args += testutils.SOFTWARE_RENDERING_ARGS
 
-    ver = webengine_versions.webengine
-    minor_version = str(ver.strip_patch())
+    quteproc_new.start(args)
+    minor_version = str(webengine_versions.webengine.strip_patch())
 
     arch = platform.machine()
     for key in [
@@ -777,6 +784,11 @@ def test_dark_mode_mathml(webengine_versions, quteproc_new, request, qtbot, suff
         '-s', 'colors.webpage.darkmode.enabled', 'true',
         '-s', 'colors.webpage.darkmode.algorithm', 'brightness-rgb',
     ]
+    if webengine_versions.webengine == utils.VersionNumber(6, 9):
+        # WORKAROUND: For unknown reasons, dark mode colors are wrong with
+        # Qt 6.9 + hardware rendering + Xvfb.
+        args += testutils.SOFTWARE_RENDERING_ARGS
+
     quteproc_new.start(args)
 
     quteproc_new.open_path(f'data/darkmode/mathml-{suffix}.html')

tests/helpers/testutils.py

@@ -330,16 +330,7 @@ def offscreen_plugin_enabled() -> bool:
 
 def use_software_rendering() -> bool:
     """Check whether to enforce software rendering for tests."""
-    if not _has_qtwebengine():
-        return False
-
-    versions = version.qtwebengine_versions(avoid_init=True)
-    return (
-        # https://github.com/qutebrowser/qutebrowser/issues/8444#issuecomment-2569554046
-        # not on CI, but unknown how to tell apart affected / unaffected systems
-        versions.webengine == utils.VersionNumber(6, 9)
-        or offscreen_plugin_enabled()
-    )
+    return _has_qtwebengine() and offscreen_plugin_enabled()
 
 
 def import_userscript(name):