Unit test alert node

shell/platform/windows/flutter_window.cc

@@ -292,6 +292,9 @@ void FlutterWindow::SendInitialAccessibilityFeatures() {
 }
 
 AccessibilityRootNode* FlutterWindow::GetAccessibilityRootNode() {
+  if (!accessibility_root_) {
+    CreateAccessibilityRootNode();
+  }
   return accessibility_root_;
 }
 

shell/platform/windows/flutter_window_unittests.cc

@@ -136,6 +136,7 @@ class MockFlutterWindow : public FlutterWindow {
   MOCK_METHOD3(Win32DispatchMessage, UINT(UINT, WPARAM, LPARAM));
   MOCK_METHOD4(Win32PeekMessage, BOOL(LPMSG, UINT, UINT, UINT));
   MOCK_METHOD1(Win32MapVkToChar, uint32_t(uint32_t));
+  MOCK_METHOD0(GetPlatformWindow, HWND());
 
  protected:
   // |KeyboardManager::WindowDelegate|
@@ -400,5 +401,32 @@ TEST(FlutterWindowTest, InitialAccessibilityFeatures) {
   win32window.SendInitialAccessibilityFeatures();
 }
 
+// Ensure that announcing the alert propagates the message to the alert node.
+// Different screen readers use different properties for alerts.
+TEST(FlutterWindowTest, AlertNode) {
+  std::unique_ptr<MockFlutterWindow> win32window = std::make_unique<MockFlutterWindow>();;
+  ON_CALL(*win32window, GetPlatformWindow()).WillByDefault(Return(nullptr));
+  AccessibilityRootNode* root_node = win32window->GetAccessibilityRootNode();
+  TestFlutterWindowsView view(std::move(win32window));
+  std::wstring message = L"Test alert";
+  view.AnnounceAlert(message);
+  IAccessible* alert = root_node->GetOrCreateAlert();
+  VARIANT self{.vt=VT_I4, .lVal=CHILDID_SELF};
+  BSTR strptr;
+  alert->get_accName(self, &strptr);
+  EXPECT_EQ(message, strptr);
+
+  alert->get_accDescription(self, &strptr);
+  EXPECT_EQ(message, strptr);
+
+  alert->get_accValue(self, &strptr);
+  EXPECT_EQ(message, strptr);
+
+  VARIANT role;
+  alert->get_accRole(self, &role);
+  EXPECT_EQ(role.vt, VT_I4);
+  EXPECT_EQ(role.lVal, ROLE_SYSTEM_ALERT);
+}
+
 }  // namespace testing
 }  // namespace flutter

shell/platform/windows/flutter_windows_view.cc

@@ -660,7 +660,9 @@ void FlutterWindowsView::AnnounceAlert(const std::wstring& text) {
   AccessibilityAlert* alert = binding_handler_->GetAccessibilityRootNode()->GetOrCreateAlert();
   alert->SetText(text);
   HWND hwnd = GetPlatformWindow();
-  NotifyWinEvent(EVENT_SYSTEM_ALERT, hwnd, OBJID_CLIENT, AccessibilityRootNode::kAlertChildId);
+  if (hwnd) {
+    NotifyWinEvent(EVENT_SYSTEM_ALERT, hwnd, OBJID_CLIENT, AccessibilityRootNode::kAlertChildId);
+  }
 }
 
 }  // namespace flutter

shell/platform/windows/window.cc

@@ -214,14 +214,7 @@ LRESULT Window::OnGetObject(UINT const message,
   } else if (is_msaa_request && root_view) {
     // Create the accessibility root if it does not already exist.
     if (!accessibility_root_) {
-      ui::win::CreateATLModuleIfNeeded();
-      CComObject<AccessibilityRootNode>* instance = nullptr;
-      HRESULT hr = CComObject<AccessibilityRootNode>::CreateInstance(&instance);
-      if (!SUCCEEDED(hr)) {
-        FML_LOG(FATAL) << "Failed to create accessibility root node";
-      }
-      instance->AddRef();
-      accessibility_root_ = instance;
+      CreateAccessibilityRootNode();
     }
     // Return the IAccessible for the root view.
     //Microsoft::WRL::ComPtr<IAccessible> root(root_view);
@@ -669,4 +662,15 @@ bool Window::GetHighContrastEnabled() {
   }
 }
 
+void Window::CreateAccessibilityRootNode() {
+  ui::win::CreateATLModuleIfNeeded();
+  CComObject<AccessibilityRootNode>* instance = nullptr;
+  HRESULT hr = CComObject<AccessibilityRootNode>::CreateInstance(&instance);
+  if (!SUCCEEDED(hr)) {
+    FML_LOG(FATAL) << "Failed to create accessibility root node";
+  }
+  instance->AddRef();
+  accessibility_root_ = instance;
+}
+
 }  // namespace flutter

shell/platform/windows/window.h

@@ -224,6 +224,9 @@ class Window : public KeyboardManager::WindowDelegate {
   // Returns the root view accessibility node, or nullptr if none.
   virtual gfx::NativeViewAccessible GetNativeViewAccessible() = 0;
 
+  // Create the wrapper node.
+  void CreateAccessibilityRootNode();
+
   // Handles running DirectManipulation on the window to receive trackpad
   // gestures.
   std::unique_ptr<DirectManipulationOwner> direct_manipulation_owner_;