[Impeller] Fail loudly if --enable-software-rendering is used. (flutter/engine#44346)

We have tests today that are trying to testwith impeller but using software rendering, so they're not actually testing with impeller.

In an unrelated patch, I'm causing the request to enable impeller to have additional checks that Impeller related objects/configurations are set when using Impeller, which isn't true if software rendering is enabled, and is causing the tests getting disabled here to fail.

The tests are not actually testing Impeller and thus are getting added to the skip list (they now crash with this change). https://github.com/flutter/flutter/issues/131888 tracks re-enabling them. They will almost certainly need different golden files than the Skia ones.

Fixes https://github.com/flutter/flutter/issues/131887

engine/src/flutter/shell/common/shell.cc

@@ -419,6 +419,8 @@ Shell::Shell(DartVMRef vm,
       volatile_path_tracker_(std::move(volatile_path_tracker)),
       weak_factory_gpu_(nullptr),
       weak_factory_(this) {
+  FML_CHECK(!settings.enable_software_rendering || !settings.enable_impeller)
+      << "Software rendering is incompatible with Impeller.";
   FML_CHECK(vm_) << "Must have access to VM to create a shell.";
   FML_DCHECK(task_runners_.IsValid());
   FML_DCHECK(task_runners_.GetPlatformTaskRunner()->RunsTasksOnCurrentThread());

engine/src/flutter/shell/common/shell_unittests.cc

@@ -4342,6 +4342,24 @@ TEST_F(ShellTest, PrintsErrorWhenPlatformMessageSentFromWrongThread) {
   ASSERT_FALSE(DartVMRef::IsInstanceRunning());
 }
 
+TEST_F(ShellTest, DiesIfSoftwareRenderingAndImpellerAreEnabledDeathTest) {
+#if defined(OS_FUCHSIA)
+  GTEST_SKIP() << "Fuchsia";
+#endif  // OS_FUCHSIA
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  Settings settings = CreateSettingsForFixture();
+  settings.enable_impeller = true;
+  settings.enable_software_rendering = true;
+  ThreadHost thread_host("io.flutter.test." + GetCurrentTestName() + ".",
+                         ThreadHost::Type::Platform);
+  auto task_runner = thread_host.platform_thread->GetTaskRunner();
+  TaskRunners task_runners("test", task_runner, task_runner, task_runner,
+                           task_runner);
+  EXPECT_DEATH_IF_SUPPORTED(
+      CreateShell(settings, task_runners),
+      "Software rendering is incompatible with Impeller.");
+}
+
 }  // namespace testing
 }  // namespace flutter
 

engine/src/flutter/testing/scenario_app/run_ios_tests.sh

@@ -78,13 +78,14 @@ echo "Running simulator tests with Impeller"
 echo ""
 
 # Skip testFontRenderingWhenSuppliedWithBogusFont: https://github.com/flutter/flutter/issues/113250
+# Skip golden tests that use software rendering: https://github.com/flutter/flutter/issues/131888
 if set -o pipefail && xcodebuild -sdk iphonesimulator \
   -scheme Scenarios \
   -resultBundlePath "$RESULT_BUNDLE_PATH/ios_scenario.xcresult" \
   -destination 'platform=iOS Simulator,OS=16.2,name=iPhone SE (3rd generation)' \
   clean test \
   FLUTTER_ENGINE="$FLUTTER_ENGINE" \
-  -skip-testing "ScenariosUITests/BogusFontTextTest/testFontRenderingWhenSuppliedWithBogusFont" \
+  -skip-testing "ScenariosUITests/BogusFontTextTest/testFontRenderingWhenSuppliedWithBogusFont,ScenarioUITests/PlatformViewMutationLargeClipRRectWithTransformTests/testPlatformView,ScenarioUITests/MultiplePlatformViewsTest/testPlatformView,ScenarioUITests/PlatformViewWithOtherBackdropFilterTests/testPlatformView,ScenarioUITests/TwoPlatformViewsWithOtherBackDropFilterTests/testPlatformView,ScenarioUITests/PlatformViewMutationClipPathTests/testPlatformView,ScenarioUITests/PlatformViewMutationClipRectWithTransformTests/testPlatformView,ScenarioUITests/PlatformViewGestureRecognizerTests/testRejectPolicyUtilTouchesEnded,ScenarioUITests/NonFullScreenFlutterViewPlatformViewUITests/testPlatformView,ScenarioUITests/PlatformViewUITests/testPlatformView,ScenarioUITests/PlatformViewMutationClipRectAfterMovedTests/testPlatformView,ScenarioUITests/PlatformViewMutationClipRectTests/testPlatformView,ScenarioUITests/TwoPlatformViewClipPathTests/testPlatformView,ScenarioUITests/MultiplePlatformViewsBackgroundForegroundTest/testPlatformView,ScenarioUITests/PlatformViewMutationOpacityTests/testPlatformView,ScenarioUITests/PlatformViewMutationClipRRectTests/testPlatformView,ScenarioUITests/PlatformViewMutationClipRRectWithTransformTests/testPlatformView,ScenarioUITests/PlatformViewMutationClipPathWithTransformTests/testPlatformView,ScenarioUITests/SpawnEngineTest/testSpawnEngineWorks,ScenarioUITests/PlatformViewRotation/testPlatformView,ScenarioUITests/TwoPlatformViewClipRRectTests/testPlatformView,ScenarioUITests/TwoPlatformViewClipRectTests/testPlatformView,ScenarioUITests/RenderingSelectionTest/testSoftwareRendering,ScenarioUITests/UnobstructedPlatformViewTests/testMultiplePlatformViewsWithOverlays,ScenarioUITests/UnobstructedPlatformViewTests/testNoOverlay,ScenarioUITests/PlatformViewMutationTransformTests/testPlatformView,ScenarioUITests/PlatformViewMutationLargeClipRRectTests/testPlatformView,ScenarioUITests/PlatformViewWithNegativeOtherBackDropFilterTests/testPlatformView" \
   INFOPLIST_FILE="Scenarios/Info_Impeller.plist"; then # Plist with FLTEnableImpeller=YES
   echo "test success."
 else