Reimplement web content accessibility by caching in browser process

chrome/browser/browser_accessibility_unittest.cc

+// Copyright (c) 2010 The Chromium 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 "base/scoped_ptr.h"
+#include "chrome/browser/browser_accessibility_manager.h"
+#include "chrome/browser/browser_accessibility.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using webkit_glue::WebAccessibility;
+
+// Subclass of BrowserAccessibility that counts the number of instances.
+class CountedBrowserAccessibility : public BrowserAccessibility {
+ public:
+  CountedBrowserAccessibility() { global_obj_count_++; }
+  virtual ~CountedBrowserAccessibility() { global_obj_count_--; }
+  static int global_obj_count_;
+};
+
+int CountedBrowserAccessibility::global_obj_count_ = 0;
+
+// Factory that creates a CountedBrowserAccessibility.
+class CountedBrowserAccessibilityFactory : public BrowserAccessibilityFactory {
+ public:
+  virtual ~CountedBrowserAccessibilityFactory() {}
+  virtual BrowserAccessibility* Create() {
+    CComObject<CountedBrowserAccessibility>* instance;
+    HRESULT hr = CComObject<CountedBrowserAccessibility>::CreateInstance(
+        &instance);
+    DCHECK(SUCCEEDED(hr));
+    return instance->NewReference();
+  }
+};
+
+// Test that BrowserAccessibilityManager correctly releases the tree of
+// BrowserAccessibility instances upon delete.
+TEST(BrowserAccessibilityTest, TestNoLeaks) {
+  // ATL needs a pointer to a COM module.
+  CComModule module;
+  _pAtlModule = &module;
+  // Make sure COM is initialized for this thread; it's safe to call twice.
+  ::CoInitialize(NULL);
+
+  // Create WebAccessibility objects for a simple document tree,
+  // representing the accessibility information used to initialize
+  // BrowserAccessibilityManager.
+  WebAccessibility button;
+  button.id = 2;
+  button.name = L"Button";
+  button.role = WebAccessibility::ROLE_PUSHBUTTON;
+  button.state = 0;
+
+  WebAccessibility checkbox;
+  checkbox.id = 3;
+  checkbox.name = L"Checkbox";
+  checkbox.role = WebAccessibility::ROLE_CHECKBUTTON;
+  checkbox.state = 0;
+
+  WebAccessibility root;
+  root.id = 1;
+  root.name = L"Document";
+  root.role = WebAccessibility::ROLE_DOCUMENT;
+  root.state = 0;
+  root.children.push_back(button);
+  root.children.push_back(checkbox);
+
+  // Construct a BrowserAccessibilityManager with this WebAccessibility tree
+  // and a factory for an instance-counting BrowserAccessibility, and ensure
+  // that exactly 3 instances were created. Note that the manager takes
+  // ownership of the factory.
+  CountedBrowserAccessibility::global_obj_count_ = 0;
+  BrowserAccessibilityManager* manager =
+      new BrowserAccessibilityManager(
+          GetDesktopWindow(), root, new CountedBrowserAccessibilityFactory());
+  ASSERT_EQ(3, CountedBrowserAccessibility::global_obj_count_);
+
+  // Delete the manager and test that all 3 instances are deleted.
+  delete manager;
+  ASSERT_EQ(0, CountedBrowserAccessibility::global_obj_count_);
+
+  // Construct a manager again, and this time use the IAccessible interface
+  // to get new references to two of the three nodes in the tree.
+  manager = new BrowserAccessibilityManager(
+      GetDesktopWindow(), root, new CountedBrowserAccessibilityFactory());
+  ASSERT_EQ(3, CountedBrowserAccessibility::global_obj_count_);
+  BrowserAccessibility* root_accessible = manager->GetRoot();
+  IDispatch* root_iaccessible = NULL;
+  IDispatch* child1_iaccessible = NULL;
+  VARIANT var_child;
+  var_child.vt = VT_I4;
+  var_child.lVal = CHILDID_SELF;
+  HRESULT hr = root_accessible->get_accChild(var_child, &root_iaccessible);
+  ASSERT_EQ(S_OK, hr);
+  var_child.lVal = 1;
+  hr = root_accessible->get_accChild(var_child, &child1_iaccessible);
+  ASSERT_EQ(S_OK, hr);
+
+  // Now delete the manager, and only one of the three nodes in the tree
+  // should be released.
+  delete manager;
+  ASSERT_EQ(2, CountedBrowserAccessibility::global_obj_count_);
+
+  // Release each of our references and make sure that each one results in
+  // the instance being deleted as its reference count hits zero.
+  root_iaccessible->Release();
+  ASSERT_EQ(1, CountedBrowserAccessibility::global_obj_count_);
+  child1_iaccessible->Release();
+  ASSERT_EQ(0, CountedBrowserAccessibility::global_obj_count_);
+}