[Linux] add FlViewAccessible tests (flutter/engine#32769)

* [Linux] make FlViewAccessible testable

Add construct-only 'engine' property to make it possible to inject a
mock engine.

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -2188,6 +2188,7 @@ FILE: ../../../flutter/shell/platform/linux/fl_value_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_view.cc
 FILE: ../../../flutter/shell/platform/linux/fl_view_accessible.cc
 FILE: ../../../flutter/shell/platform/linux/fl_view_accessible.h
+FILE: ../../../flutter/shell/platform/linux/fl_view_accessible_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_view_private.h
 FILE: ../../../flutter/shell/platform/linux/key_mapping.cc
 FILE: ../../../flutter/shell/platform/linux/key_mapping.h

engine/src/flutter/shell/platform/linux/BUILD.gn

@@ -214,6 +214,7 @@ executable("flutter_linux_unittests") {
     "fl_texture_gl_test.cc",
     "fl_texture_registrar_test.cc",
     "fl_value_test.cc",
+    "fl_view_accessible_test.cc",
     "testing/fl_test.cc",
     "testing/mock_binary_messenger.cc",
     "testing/mock_binary_messenger_response_handle.cc",

engine/src/flutter/shell/platform/linux/fl_view_accessible.cc

@@ -9,14 +9,33 @@
 struct _FlViewAccessible {
   GtkContainerAccessible parent_instance;
 
+  FlEngine* engine;
+
   // Semantics nodes keyed by ID
   GHashTable* semantics_nodes_by_id;
 };
 
+enum { PROP_0, PROP_ENGINE, PROP_LAST };
+
 G_DEFINE_TYPE(FlViewAccessible,
               fl_view_accessible,
               GTK_TYPE_CONTAINER_ACCESSIBLE)
 
+static void init_engine(FlViewAccessible* self, FlEngine* engine) {
+  g_assert(self->engine == nullptr);
+  self->engine = engine;
+  g_object_add_weak_pointer(G_OBJECT(self),
+                            reinterpret_cast<gpointer*>(&self->engine));
+}
+
+static FlEngine* get_engine(FlViewAccessible* self) {
+  if (self->engine == nullptr) {
+    FlView* view = FL_VIEW(gtk_accessible_get_widget(GTK_ACCESSIBLE(self)));
+    init_engine(self, fl_view_get_engine(view));
+  }
+  return self->engine;
+}
+
 // Gets the ATK node for the given id.
 // If the node doesn't exist it will be created.
 static FlAccessibleNode* get_node(FlViewAccessible* self, int32_t id) {
@@ -26,8 +45,8 @@ static FlAccessibleNode* get_node(FlViewAccessible* self, int32_t id) {
     return node;
   }
 
-  FlView* view = FL_VIEW(gtk_accessible_get_widget(GTK_ACCESSIBLE(self)));
-  node = fl_accessible_node_new(fl_view_get_engine(view), id);
+  FlEngine* engine = get_engine(self);
+  node = fl_accessible_node_new(engine, id);
   if (id == 0) {
     fl_accessible_node_set_parent(node, ATK_OBJECT(self), 0);
   }
@@ -59,10 +78,48 @@ static AtkRole fl_view_accessible_get_role(AtkObject* accessible) {
   return ATK_ROLE_PANEL;
 }
 
+// Implements GObject::set_property
+static void fl_view_accessible_set_property(GObject* object,
+                                            guint prop_id,
+                                            const GValue* value,
+                                            GParamSpec* pspec) {
+  FlViewAccessible* self = FL_VIEW_ACCESSIBLE(object);
+  switch (prop_id) {
+    case PROP_ENGINE:
+      init_engine(self, FL_ENGINE(g_value_get_object(value)));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
+      break;
+  }
+}
+
+static void fl_view_accessible_dispose(GObject* object) {
+  FlViewAccessible* self = FL_VIEW_ACCESSIBLE(object);
+
+  if (self->engine != nullptr) {
+    g_object_remove_weak_pointer(object,
+                                 reinterpret_cast<gpointer*>(&self->engine));
+    self->engine = nullptr;
+  }
+
+  G_OBJECT_CLASS(fl_view_accessible_parent_class)->dispose(object);
+}
+
 static void fl_view_accessible_class_init(FlViewAccessibleClass* klass) {
   ATK_OBJECT_CLASS(klass)->get_n_children = fl_view_accessible_get_n_children;
   ATK_OBJECT_CLASS(klass)->ref_child = fl_view_accessible_ref_child;
   ATK_OBJECT_CLASS(klass)->get_role = fl_view_accessible_get_role;
+
+  G_OBJECT_CLASS(klass)->dispose = fl_view_accessible_dispose;
+  G_OBJECT_CLASS(klass)->set_property = fl_view_accessible_set_property;
+
+  g_object_class_install_property(
+      G_OBJECT_CLASS(klass), PROP_ENGINE,
+      g_param_spec_object(
+          "engine", "engine", "Flutter engine", fl_engine_get_type(),
+          static_cast<GParamFlags>(G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY |
+                                   G_PARAM_STATIC_STRINGS)));
 }
 
 static void fl_view_accessible_init(FlViewAccessible* self) {

engine/src/flutter/shell/platform/linux/fl_view_accessible_test.cc

@@ -0,0 +1,157 @@
+// 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.
+
+// Included first as it collides with the X11 headers.
+#include "gtest/gtest.h"
+
+#include "flutter/shell/platform/linux/fl_view_accessible.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_engine.h"
+#include "flutter/shell/platform/linux/testing/fl_test.h"
+#include "flutter/shell/platform/linux/testing/mock_signal_handler.h"
+
+TEST(FlViewAccessibleTest, BuildTree) {
+  g_autoptr(FlEngine) engine = make_mock_engine();
+  g_autoptr(FlViewAccessible) accessible = FL_VIEW_ACCESSIBLE(
+      g_object_new(fl_view_accessible_get_type(), "engine", engine, nullptr));
+
+  const int32_t children[] = {111, 222};
+  const FlutterSemanticsNode root_node = {
+      .id = 0,
+      .label = "root",
+      .child_count = 2,
+      .children_in_traversal_order = children,
+  };
+  fl_view_accessible_handle_update_semantics_node(accessible, &root_node);
+
+  const FlutterSemanticsNode child1_node = {.id = 111, .label = "child 1"};
+  fl_view_accessible_handle_update_semantics_node(accessible, &child1_node);
+
+  const FlutterSemanticsNode child2_node = {.id = 222, .label = "child 2"};
+  fl_view_accessible_handle_update_semantics_node(accessible, &child2_node);
+
+  AtkObject* root_object =
+      atk_object_ref_accessible_child(ATK_OBJECT(accessible), 0);
+  EXPECT_STREQ(atk_object_get_name(root_object), "root");
+  EXPECT_EQ(atk_object_get_index_in_parent(root_object), 0);
+  EXPECT_EQ(atk_object_get_n_accessible_children(root_object), 2);
+
+  AtkObject* child1_object = atk_object_ref_accessible_child(root_object, 0);
+  EXPECT_STREQ(atk_object_get_name(child1_object), "child 1");
+  EXPECT_EQ(atk_object_get_parent(child1_object), root_object);
+  EXPECT_EQ(atk_object_get_index_in_parent(child1_object), 0);
+  EXPECT_EQ(atk_object_get_n_accessible_children(child1_object), 0);
+
+  AtkObject* child2_object = atk_object_ref_accessible_child(root_object, 1);
+  EXPECT_STREQ(atk_object_get_name(child2_object), "child 2");
+  EXPECT_EQ(atk_object_get_parent(child2_object), root_object);
+  EXPECT_EQ(atk_object_get_index_in_parent(child2_object), 1);
+  EXPECT_EQ(atk_object_get_n_accessible_children(child2_object), 0);
+}
+
+TEST(FlViewAccessibleTest, AddRemoveChildren) {
+  g_autoptr(FlEngine) engine = make_mock_engine();
+  g_autoptr(FlViewAccessible) accessible = FL_VIEW_ACCESSIBLE(
+      g_object_new(fl_view_accessible_get_type(), "engine", engine, nullptr));
+
+  FlutterSemanticsNode root_node = {
+      .id = 0,
+      .label = "root",
+      .child_count = 0,
+  };
+  fl_view_accessible_handle_update_semantics_node(accessible, &root_node);
+
+  AtkObject* root_object =
+      atk_object_ref_accessible_child(ATK_OBJECT(accessible), 0);
+  EXPECT_EQ(atk_object_get_n_accessible_children(root_object), 0);
+
+  // add child1
+  AtkObject* child1_object = nullptr;
+  {
+    flutter::testing::MockSignalHandler2<gint, AtkObject*> child1_added(
+        root_object, "children-changed::add");
+    EXPECT_SIGNAL2(child1_added, ::testing::Eq(0), ::testing::A<AtkObject*>())
+        .WillOnce(::testing::SaveArg<1>(&child1_object));
+
+    const int32_t children[] = {111};
+    root_node.child_count = 1;
+    root_node.children_in_traversal_order = children;
+    fl_view_accessible_handle_update_semantics_node(accessible, &root_node);
+
+    const FlutterSemanticsNode child1_node = {.id = 111, .label = "child 1"};
+    fl_view_accessible_handle_update_semantics_node(accessible, &child1_node);
+  }
+
+  EXPECT_EQ(atk_object_get_n_accessible_children(root_object), 1);
+  EXPECT_EQ(atk_object_ref_accessible_child(root_object, 0), child1_object);
+
+  EXPECT_STREQ(atk_object_get_name(child1_object), "child 1");
+  EXPECT_EQ(atk_object_get_parent(child1_object), root_object);
+  EXPECT_EQ(atk_object_get_index_in_parent(child1_object), 0);
+  EXPECT_EQ(atk_object_get_n_accessible_children(child1_object), 0);
+
+  // add child2
+  AtkObject* child2_object = nullptr;
+  {
+    flutter::testing::MockSignalHandler2<gint, AtkObject*> child2_added(
+        root_object, "children-changed::add");
+    EXPECT_SIGNAL2(child2_added, ::testing::Eq(1), ::testing::A<AtkObject*>())
+        .WillOnce(::testing::SaveArg<1>(&child2_object));
+
+    const int32_t children[] = {111, 222};
+    root_node.child_count = 2;
+    root_node.children_in_traversal_order = children;
+    fl_view_accessible_handle_update_semantics_node(accessible, &root_node);
+
+    const FlutterSemanticsNode child2_node = {.id = 222, .label = "child 2"};
+    fl_view_accessible_handle_update_semantics_node(accessible, &child2_node);
+  }
+
+  EXPECT_EQ(atk_object_get_n_accessible_children(root_object), 2);
+  EXPECT_EQ(atk_object_ref_accessible_child(root_object, 0), child1_object);
+  EXPECT_EQ(atk_object_ref_accessible_child(root_object, 1), child2_object);
+
+  EXPECT_STREQ(atk_object_get_name(child1_object), "child 1");
+  EXPECT_EQ(atk_object_get_parent(child1_object), root_object);
+  EXPECT_EQ(atk_object_get_index_in_parent(child1_object), 0);
+  EXPECT_EQ(atk_object_get_n_accessible_children(child1_object), 0);
+
+  EXPECT_STREQ(atk_object_get_name(child2_object), "child 2");
+  EXPECT_EQ(atk_object_get_parent(child2_object), root_object);
+  EXPECT_EQ(atk_object_get_index_in_parent(child2_object), 1);
+  EXPECT_EQ(atk_object_get_n_accessible_children(child2_object), 0);
+
+  // remove child1
+  {
+    flutter::testing::MockSignalHandler2<gint, AtkObject*> child1_removed(
+        root_object, "children-changed::remove");
+    EXPECT_SIGNAL2(child1_removed, ::testing::Eq(0),
+                   ::testing::Eq(child1_object));
+
+    const int32_t children[] = {222};
+    root_node.child_count = 1;
+    root_node.children_in_traversal_order = children;
+    fl_view_accessible_handle_update_semantics_node(accessible, &root_node);
+  }
+
+  EXPECT_EQ(atk_object_get_n_accessible_children(root_object), 1);
+  EXPECT_EQ(atk_object_ref_accessible_child(root_object, 0), child2_object);
+
+  EXPECT_STREQ(atk_object_get_name(child2_object), "child 2");
+  EXPECT_EQ(atk_object_get_parent(child2_object), root_object);
+  EXPECT_EQ(atk_object_get_index_in_parent(child2_object), 0);
+  EXPECT_EQ(atk_object_get_n_accessible_children(child2_object), 0);
+
+  // remove child2
+  {
+    flutter::testing::MockSignalHandler2<gint, AtkObject*> child2_removed(
+        root_object, "children-changed::remove");
+    EXPECT_SIGNAL2(child2_removed, ::testing::Eq(0),
+                   ::testing::Eq(child2_object));
+
+    root_node.child_count = 0;
+    fl_view_accessible_handle_update_semantics_node(accessible, &root_node);
+  }
+
+  EXPECT_EQ(atk_object_get_n_accessible_children(root_object), 0);
+}