Support fixture tests for Windows embedder

This adds support for running end-to-end tests that use a live engine to
run Dart test fixtures. This enables testing the public Windows C API in
//flutter/shell/platform/windows/public/flutter_windows.h

This only adds support for a single test entrypoint (main). A followup
patch will add support for this. See:
flutter/flutter#93537

Issue: flutter/flutter#87299

ci/licenses_golden/licenses_flutter

@@ -2449,6 +2449,12 @@ FILE: ../../../flutter/shell/platform/windows/task_runner.h
 FILE: ../../../flutter/shell/platform/windows/task_runner_unittests.cc
 FILE: ../../../flutter/shell/platform/windows/task_runner_window.cc
 FILE: ../../../flutter/shell/platform/windows/task_runner_window.h
+FILE: ../../../flutter/shell/platform/windows/testing/windows_test.cc
+FILE: ../../../flutter/shell/platform/windows/testing/windows_test.h
+FILE: ../../../flutter/shell/platform/windows/testing/windows_test_config_builder.cc
+FILE: ../../../flutter/shell/platform/windows/testing/windows_test_config_builder.h
+FILE: ../../../flutter/shell/platform/windows/testing/windows_test_context.cc
+FILE: ../../../flutter/shell/platform/windows/testing/windows_test_context.h
 FILE: ../../../flutter/shell/platform/windows/text_input_manager.cc
 FILE: ../../../flutter/shell/platform/windows/text_input_manager.h
 FILE: ../../../flutter/shell/platform/windows/text_input_plugin.cc

shell/platform/windows/BUILD.gn

@@ -158,6 +158,7 @@ shared_library("flutter_windows") {
 }
 
 test_fixtures("flutter_windows_fixtures") {
+  dart_main = "fixtures/main.dart"
   fixtures = []
 }
 
@@ -198,6 +199,12 @@ executable("flutter_windows_unittests") {
     "testing/test_keyboard.cc",
     "testing/test_keyboard.h",
     "testing/test_keyboard_unittests.cc",
+    "testing/windows_test.cc",
+    "testing/windows_test.h",
+    "testing/windows_test_config_builder.cc",
+    "testing/windows_test_config_builder.h",
+    "testing/windows_test_context.cc",
+    "testing/windows_test_context.h",
     "testing/wm_builders.cc",
     "testing/wm_builders.h",
     "text_input_plugin_unittest.cc",

shell/platform/windows/fixtures/main.dart

@@ -0,0 +1,7 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+void main() {
+  print('Hello windows engine test!');
+}

shell/platform/windows/flutter_windows_unittests.cc

@@ -5,13 +5,17 @@
 #include "flutter/shell/platform/windows/public/flutter_windows.h"
 
 #include <cstring>
+#include <thread>
 
+#include "flutter/shell/platform/windows/testing/windows_test.h"
+#include "flutter/shell/platform/windows/testing/windows_test_config_builder.h"
+#include "flutter/shell/platform/windows/testing/windows_test_context.h"
 #include "gtest/gtest.h"
 
 namespace flutter {
 namespace testing {
 
-TEST(FlutterWindowsTest, GetTextureRegistrar) {
+TEST(WindowsNoFixtureTest, GetTextureRegistrar) {
   FlutterDesktopEngineProperties properties;
   memset(&properties, 0, sizeof(FlutterDesktopEngineProperties));
   properties.assets_path = L"";
@@ -23,5 +27,19 @@ TEST(FlutterWindowsTest, GetTextureRegistrar) {
   FlutterDesktopEngineDestroy(engine);
 }
 
+TEST_F(WindowsTest, LaunchMain) {
+  auto& context = GetContext();
+  WindowsConfigBuilder builder(context);
+  ViewControllerPtr controller{builder.LaunchEngine()};
+  ASSERT_NE(controller, nullptr);
+
+  // Run for 1 second, then shut down.
+  //
+  // TODO(cbracken): Support registring a native function we can use to
+  // determine that execution has made it to a specific point in the Dart
+  // code. https://github.com/flutter/flutter/issues/109242
+  std::this_thread::sleep_for(std::chrono::seconds(1));
+}
+
 }  // namespace testing
 }  // namespace flutter

shell/platform/windows/testing/windows_test.cc

@@ -0,0 +1,26 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/testing/windows_test.h"
+
+#include <string>
+
+#include "flutter/shell/platform/windows/testing/windows_test_context.h"
+#include "flutter/testing/testing.h"
+
+namespace flutter {
+namespace testing {
+
+WindowsTest::WindowsTest() : context_(GetFixturesDirectory()) {}
+
+std::string WindowsTest::GetFixturesDirectory() const {
+  return GetFixturesPath();
+}
+
+WindowsTestContext& WindowsTest::GetContext() {
+  return context_;
+}
+
+}  // namespace testing
+}  // namespace flutter

shell/platform/windows/testing/windows_test.h

@@ -0,0 +1,46 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_WINDOWS_TEST_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_WINDOWS_TEST_H_
+
+#include <string>
+
+#include "flutter/fml/macros.h"
+#include "flutter/shell/platform/windows/testing/windows_test_context.h"
+#include "flutter/testing/thread_test.h"
+
+namespace flutter {
+namespace testing {
+
+/// A GoogleTest test fixture for Windows tests.
+///
+/// Supports looking up the test fixture data defined in the GN `test_fixtures`
+/// associated with the unit test executable target. This typically includes
+/// the kernel bytecode `kernel_blob.bin` compiled from the Dart file specified
+/// in the test fixture's `dart_main` property, as well as any other data files
+/// used in tests, such as image files used in a screenshot golden test.
+///
+/// This test class can be used in GoogleTest tests using the standard
+/// `TEST_F(WindowsTest, TestName)` macro.
+class WindowsTest : public ThreadTest {
+ public:
+  WindowsTest();
+
+  // Returns the path to test fixture data such as kernel bytecode or images
+  // used by the C++ side of the test.
+  std::string GetFixturesDirectory() const;
+
+  // Returns the test context associated with this fixture.
+  WindowsTestContext& GetContext();
+
+ private:
+  WindowsTestContext context_;
+  FML_DISALLOW_COPY_AND_ASSIGN(WindowsTest);
+};
+
+}  // namespace testing
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_WINDOWS_TEST_H_

shell/platform/windows/testing/windows_test_config_builder.cc

@@ -0,0 +1,87 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/testing/windows_test_config_builder.h"
+
+#include <combaseapi.h>
+
+#include <string>
+#include <string_view>
+#include <vector>
+
+#include "flutter/fml/logging.h"
+#include "flutter/shell/platform/windows/public/flutter_windows.h"
+#include "flutter/shell/platform/windows/testing/windows_test_context.h"
+
+namespace flutter {
+namespace testing {
+
+WindowsConfigBuilder::WindowsConfigBuilder(WindowsTestContext& context)
+    : context_(context) {}
+
+WindowsConfigBuilder::~WindowsConfigBuilder() = default;
+
+void WindowsConfigBuilder::AddDartEntrypointArgument(std::string_view arg) {
+  if (arg.empty()) {
+    return;
+  }
+
+  dart_entrypoint_arguments_.emplace_back(std::move(arg));
+}
+
+FlutterDesktopEngineProperties WindowsConfigBuilder::GetEngineProperties()
+    const {
+  FlutterDesktopEngineProperties engine_properties = {};
+  engine_properties.assets_path = context_.GetAssetsPath().c_str();
+  engine_properties.icu_data_path = context_.GetIcuDataPath().c_str();
+
+  // Set Dart entrypoint argc, argv.
+  std::vector<const char*> dart_args;
+  dart_args.reserve(dart_entrypoint_arguments_.size());
+  for (const auto& arg : dart_entrypoint_arguments_) {
+    dart_args.push_back(arg.c_str());
+  }
+  if (!dart_args.empty()) {
+    engine_properties.dart_entrypoint_argv = dart_args.data();
+    engine_properties.dart_entrypoint_argc = dart_args.size();
+  } else {
+    // Clear this out in case this is not the first engine launch from the
+    // embedder config builder.
+    engine_properties.dart_entrypoint_argv = nullptr;
+    engine_properties.dart_entrypoint_argc = 0;
+  }
+
+  return engine_properties;
+}
+
+ViewControllerPtr WindowsConfigBuilder::LaunchEngine() const {
+  InitializeCOM();
+
+  EnginePtr engine = InitializeEngine();
+  if (!engine) {
+    return {};
+  }
+
+  int width = 600;
+  int height = 400;
+  ViewControllerPtr controller(
+      FlutterDesktopViewControllerCreate(width, height, engine.release()));
+  if (!controller) {
+    return {};
+  }
+
+  return controller;
+}
+
+void WindowsConfigBuilder::InitializeCOM() const {
+  FML_CHECK(SUCCEEDED(::CoInitializeEx(nullptr, COINIT_MULTITHREADED)));
+}
+
+EnginePtr WindowsConfigBuilder::InitializeEngine() const {
+  FlutterDesktopEngineProperties engine_properties = GetEngineProperties();
+  return EnginePtr(FlutterDesktopEngineCreate(&engine_properties));
+}
+
+}  // namespace testing
+}  // namespace flutter

shell/platform/windows/testing/windows_test_config_builder.h

@@ -0,0 +1,79 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_WINDOWS_TEST_CONFIG_BUILDER_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_WINDOWS_TEST_CONFIG_BUILDER_H_
+
+#include <string>
+#include <string_view>
+#include <vector>
+
+#include "flutter/fml/macros.h"
+#include "flutter/fml/unique_object.h"
+#include "flutter/shell/platform/windows/public/flutter_windows.h"
+#include "flutter/shell/platform/windows/testing/windows_test_context.h"
+
+namespace flutter {
+namespace testing {
+
+// Deleter for FlutterDesktopEngineRef objects.
+struct EngineDeleter {
+  typedef FlutterDesktopEngineRef pointer;
+  void operator()(FlutterDesktopEngineRef engine) {
+    bool destroyed = FlutterDesktopEngineDestroy(engine);
+    FML_CHECK(destroyed);
+  }
+};
+
+// Unique pointer wrapper for FlutterDesktopEngineRef.
+using EnginePtr = std::unique_ptr<FlutterDesktopEngine, EngineDeleter>;
+
+// Deleter for FlutterViewControllerRef objects.
+struct ViewControllerDeleter {
+  typedef FlutterDesktopViewControllerRef pointer;
+  void operator()(FlutterDesktopViewControllerRef engine) {
+    FlutterDesktopViewControllerDestroy(engine);
+  }
+};
+
+// Unique pointer wrapper for FlutterDesktopViewControllerRef.
+using ViewControllerPtr =
+    std::unique_ptr<FlutterDesktopViewControllerState, ViewControllerDeleter>;
+
+// Test configuration builder for WindowsTests.
+//
+// Utility class for configuring engine and view controller launch arguments,
+// and launching the engine to run a test fixture.
+class WindowsConfigBuilder {
+ public:
+  explicit WindowsConfigBuilder(WindowsTestContext& context);
+  ~WindowsConfigBuilder();
+
+  // Returns the desktop engine properties configured for this test.
+  FlutterDesktopEngineProperties GetEngineProperties() const;
+
+  // Adds an argument to the Dart entrypoint arguments List<String>.
+  void AddDartEntrypointArgument(std::string_view arg);
+
+  // Returns a configured and initialized view controller running the default
+  // Dart entrypoint.
+  ViewControllerPtr LaunchEngine() const;
+
+ private:
+  // Initialize COM, so that it is available for use in the library and/or
+  // plugins.
+  void InitializeCOM() const;
+
+  // Returns a configured and initialized engine.
+  EnginePtr InitializeEngine() const;
+
+  WindowsTestContext& context_;
+  std::vector<std::string> dart_entrypoint_arguments_;
+  FML_DISALLOW_COPY_AND_ASSIGN(WindowsConfigBuilder);
+};
+
+}  // namespace testing
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_WINDOWS_TEST_CONFIG_BUILDER_H_

shell/platform/windows/testing/windows_test_context.cc

@@ -0,0 +1,26 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/testing/windows_test_context.h"
+
+#include "flutter/fml/platform/win/wstring_conversion.h"
+
+namespace flutter {
+namespace testing {
+
+WindowsTestContext::WindowsTestContext(std::string_view assets_path)
+    : assets_path_(fml::Utf8ToWideString(assets_path)) {}
+
+WindowsTestContext::~WindowsTestContext() = default;
+
+const std::wstring& WindowsTestContext::GetAssetsPath() const {
+  return assets_path_;
+}
+
+const std::wstring& WindowsTestContext::GetIcuDataPath() const {
+  return icu_data_path_;
+}
+
+}  // namespace testing
+}  // namespace flutter

shell/platform/windows/testing/windows_test_context.h

@@ -0,0 +1,40 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_WINDOWS_TEST_CONTEXT_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_WINDOWS_TEST_CONTEXT_H_
+
+#include <string>
+#include <string_view>
+
+#include "flutter/fml/macros.h"
+
+namespace flutter {
+namespace testing {
+
+// Context associated with the current Windows test fixture.
+//
+// Context data includes global Flutter and Dart runtime context such as the
+// path of Flutter's asset directory, ICU path, and resolvers for any
+// registered native functions.
+class WindowsTestContext {
+ public:
+  explicit WindowsTestContext(std::string_view assets_path = "");
+  virtual ~WindowsTestContext();
+
+  const std::wstring& GetAssetsPath() const;
+
+  const std::wstring& GetIcuDataPath() const;
+
+ private:
+  std::wstring assets_path_;
+  std::wstring icu_data_path_ = L"icudtl.dat";
+
+  FML_DISALLOW_COPY_AND_ASSIGN(WindowsTestContext);
+};
+
+}  // namespace testing
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_TESTING_WINDOWS_TEST_CONTEXT_H_