Make tree serialization more robust and add more unit tests.

ui/accessibility/ax_tree_serializer_unittest.cc

Index: ui/accessibility/ax_tree_serializer_unittest.cc
diff --git a/ui/accessibility/ax_tree_serializer_unittest.cc b/ui/accessibility/ax_tree_serializer_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..806c411486289ba44dc6e2c1b08ed3572b573ee2
--- /dev/null
+++ b/ui/accessibility/ax_tree_serializer_unittest.cc
@@ -0,0 +1,182 @@
+// Copyright 2013 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/memory/scoped_ptr.h"
+#include "base/strings/string_number_conversions.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "ui/accessibility/ax_node.h"
+#include "ui/accessibility/ax_serializable_tree.h"
+#include "ui/accessibility/ax_tree.h"
+#include "ui/accessibility/ax_tree_serializer.h"
+
+namespace ui {
+
+// The framework for these tests is that each test sets up |treedata0_|
+// and |treedata1_| and then calls GetTreeSerializer, which creates a
+// serializer for a tree that's initially in state |treedata0_|, but then
+// changes to state |treedata1_|. This allows each test to check the
+// updates created by AXTreeSerializer or unit-test its private
+// member functions.
+class AXTreeSerializerTest : public testing::Test {
+ public:
+  AXTreeSerializerTest() {}
+  virtual ~AXTreeSerializerTest() {}
+
+ protected:
+  void CreateTreeSerializer();
+
+  AXTreeUpdate treedata0_;
+  AXTreeUpdate treedata1_;
+  scoped_ptr<AXSerializableTree> tree0_;
+  scoped_ptr<AXSerializableTree> tree1_;
+  scoped_ptr<AXTreeSource<AXNode> > tree0_source_;
+  scoped_ptr<AXTreeSource<AXNode> > tree1_source_;
+  scoped_ptr<AXTreeSerializer<AXNode> > serializer_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(AXTreeSerializerTest);
+};
+
+void AXTreeSerializerTest::CreateTreeSerializer() {
+  if (serializer_)
+    return;
+
+  tree0_.reset(new AXSerializableTree(treedata0_));
+  tree1_.reset(new AXSerializableTree(treedata1_));
+
+  // Serialize tree0 so that AXTreeSerializer thinks that its client
+  // is totally in sync.
+  tree0_source_.reset(tree0_->CreateTreeSource());
+  serializer_.reset(new AXTreeSerializer<AXNode>(tree0_source_.get()));
+  AXTreeUpdate update0;

[aboxhall, 2013/12/03 15:50:14]

Might be nice to make explicit that this is never used (e.g. unused_update or
unused_update0).

[dmazzoni, 2013/12/03 16:46:51]

Good idea, done.

+  serializer_->SerializeChanges(tree0_->GetRoot(), &update0);
+
+  // Pretend that tree0_ turned into tree1_. The next call to
+  // AXTreeSerializer will force it to consider these changes to
+  // the tree and send them as part of the next update.
+  tree1_source_.reset(tree1_->CreateTreeSource());
+  serializer_->ChangeTreeSourceForTesting(tree1_source_.get());
+}
+
+// In this test, one child is added to the root. Only the root and
+// new child should be added.
+TEST_F(AXTreeSerializerTest, UpdateContainsOnlyChangedNodes) {
+  // (1 (2 3))
+  treedata0_.nodes.resize(3);
+  treedata0_.nodes[0].id = 1;
+  treedata0_.nodes[0].role = AX_ROLE_ROOT_WEB_AREA;
+  treedata0_.nodes[0].child_ids.push_back(2);
+  treedata0_.nodes[0].child_ids.push_back(3);
+  treedata0_.nodes[1].id = 2;
+  treedata0_.nodes[2].id = 3;
+
+  // (1 (4 2 3))
+  treedata1_.nodes.resize(4);
+  treedata1_.nodes[0].id = 1;
+  treedata1_.nodes[0].role = AX_ROLE_ROOT_WEB_AREA;
+  treedata1_.nodes[0].child_ids.push_back(4);
+  treedata1_.nodes[0].child_ids.push_back(2);
+  treedata1_.nodes[0].child_ids.push_back(3);
+  treedata1_.nodes[1].id = 2;
+  treedata1_.nodes[2].id = 3;
+  treedata1_.nodes[3].id = 4;
+
+  CreateTreeSerializer();
+  AXTreeUpdate update;
+  serializer_->SerializeChanges(tree1_->GetFromId(1), &update);
+
+  // The update should only touch nodes 1 and 4 - nodes 2 and 3 are unchanged
+  // and shouldn't be affected.
+  EXPECT_EQ(0, update.node_id_to_clear);
+  ASSERT_EQ(static_cast<size_t>(2), update.nodes.size());
+  EXPECT_EQ(1, update.nodes[0].id);
+  EXPECT_EQ(4, update.nodes[1].id);
+}
+
+// When the root changes, the whole tree is updated, even if some of it
+// is unaffected.
+TEST_F(AXTreeSerializerTest, NewRootUpdatesEntireTree) {
+  // (1 (2 (3 (4))))
+  treedata0_.nodes.resize(4);
+  treedata0_.nodes[0].id = 1;
+  treedata0_.nodes[0].role = AX_ROLE_ROOT_WEB_AREA;
+  treedata0_.nodes[0].child_ids.push_back(2);
+  treedata0_.nodes[1].id = 2;
+  treedata0_.nodes[1].child_ids.push_back(3);
+  treedata0_.nodes[2].id = 3;
+  treedata0_.nodes[2].child_ids.push_back(4);
+  treedata0_.nodes[3].id = 4;
+
+  // (5 (2 (3 (4))))
+  treedata1_.nodes.resize(4);
+  treedata1_.nodes[0].id = 5;
+  treedata1_.nodes[0].role = AX_ROLE_ROOT_WEB_AREA;
+  treedata1_.nodes[0].child_ids.push_back(2);
+  treedata1_.nodes[1].id = 2;
+  treedata1_.nodes[1].child_ids.push_back(3);
+  treedata1_.nodes[2].id = 3;
+  treedata1_.nodes[2].child_ids.push_back(4);
+  treedata1_.nodes[3].id = 4;
+
+  CreateTreeSerializer();
+  AXTreeUpdate update;
+  serializer_->SerializeChanges(tree1_->GetFromId(4), &update);
+
+  // The update should delete the subtree rooted at node id=1, and
+  // then include all four nodes in the update, even though the
+  // subtree rooted at id=2 didn't actually change.
+  EXPECT_EQ(1, update.node_id_to_clear);
+  ASSERT_EQ(static_cast<size_t>(4), update.nodes.size());
+  EXPECT_EQ(5, update.nodes[0].id);
+  EXPECT_EQ(2, update.nodes[1].id);
+  EXPECT_EQ(3, update.nodes[2].id);
+  EXPECT_EQ(4, update.nodes[3].id);
+}
+
+// When a node is reparented, the subtree including both the old parent
+// and new parent of the reparented node must be deleted and recreated.
+TEST_F(AXTreeSerializerTest, ReparentingUpdatesSubtree) {
+  // (1 (2 (3 (4) 5)))
+  treedata0_.nodes.resize(5);
+  treedata0_.nodes[0].id = 1;
+  treedata0_.nodes[0].role = AX_ROLE_ROOT_WEB_AREA;
+  treedata0_.nodes[0].child_ids.push_back(2);
+  treedata0_.nodes[1].id = 2;
+  treedata0_.nodes[1].child_ids.push_back(3);
+  treedata0_.nodes[1].child_ids.push_back(5);
+  treedata0_.nodes[2].id = 3;
+  treedata0_.nodes[2].child_ids.push_back(4);
+  treedata0_.nodes[3].id = 4;
+  treedata0_.nodes[4].id = 5;
+
+  // Node 5 has been reparented from being a child of node 2,
+  // to a child of node 4.
+  // (1 (2 (3 (4 (5)))))
+  treedata1_.nodes.resize(5);
+  treedata1_.nodes[0].id = 1;
+  treedata1_.nodes[0].role = AX_ROLE_ROOT_WEB_AREA;
+  treedata1_.nodes[0].child_ids.push_back(2);
+  treedata1_.nodes[1].id = 2;
+  treedata1_.nodes[1].child_ids.push_back(3);
+  treedata1_.nodes[2].id = 3;
+  treedata1_.nodes[2].child_ids.push_back(4);
+  treedata1_.nodes[3].id = 4;
+  treedata1_.nodes[3].child_ids.push_back(5);
+  treedata1_.nodes[4].id = 5;
+
+  CreateTreeSerializer();
+  AXTreeUpdate update;
+  serializer_->SerializeChanges(tree1_->GetFromId(4), &update);
+
+  // The update should delete the subtree rooted at node id=2, and
+  // then include nodes 2...5.
+  EXPECT_EQ(2, update.node_id_to_clear);
+  ASSERT_EQ(static_cast<size_t>(4), update.nodes.size());
+  EXPECT_EQ(2, update.nodes[0].id);
+  EXPECT_EQ(3, update.nodes[1].id);
+  EXPECT_EQ(4, update.nodes[2].id);
+  EXPECT_EQ(5, update.nodes[3].id);
+}
+
+}  // namespace ui