chrome/browser/browser_accessibility_win_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_win.h"
#include "chrome/browser/browser_accessibility_win.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_BUTTON;
  button.state = 0;

  WebAccessibility checkbox;
  checkbox.id = 3;
  checkbox.name = L"Checkbox";
  checkbox.role = WebAccessibility::ROLE_CHECKBOX;
  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, NULL,
          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, NULL,
      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_);
}