Add ListContainer::swap

Source/platform/graphics/ListContainerTest.cpp

 // Copyright 2015 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 "config.h"
 #include "platform/graphics/ListContainer.h"
 
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefPtr.h"
@@ skipping 95 matching lines @@
 };
 
 class SimpleDerivedElementConstructMagicNumberTwo : public SimpleDerivedElement {
 public:
     SimpleDerivedElementConstructMagicNumberTwo()
     {
         setValue(kMagicNumberToUseForSimpleDerivedElementTwo);
     }
 };
 
+class SimpleDerivedElementConstructMagicNumberThree : public SimpleDerivedElement {
+public:
+    SimpleDerivedElementConstructMagicNumberThree()
+    {
+        setValue(kMagicNumberToUseForSimpleDerivedElementThree);
+    }
+};
+
 class MockDerivedElement : public SimpleDerivedElementConstructMagicNumberOne {
 public:
     ~MockDerivedElement() override { Destruct(); }
     MOCK_METHOD0(Destruct, void());
 };
 
 class MockDerivedElementSubclass : public MockDerivedElement {
 public:
     MockDerivedElementSubclass()
     {
@@ skipping 806 matching lines @@
     list.appendByMoving(list.front());
     EXPECT_TRUE(static_cast<LongSimpleDerivedElement*>(list.back())->areAllValuesEqualTo(kMagicNumberToUseForLongSimpleDerivedElement));
     EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementOne, simpleElement->getValue());
 
     LongSimpleDerivedElement* longElement = static_cast<LongSimpleDerivedElement*>(list.back());
     list.appendByMoving(simpleElement);
     EXPECT_TRUE(longElement->areAllValuesEqualTo(kMagicNumberToUseForLongSimpleDerivedElement));
     EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementOne, list.back()->getValue());
 }
 
+TEST(ListContainerTest, Swap)
+{
+    ListContainer<SimpleDerivedElement> list1(kCurrentLargestDerivedElementSize);
+    list1.allocateAndConstruct<SimpleDerivedElementConstructMagicNumberOne>();
+    ListContainer<SimpleDerivedElement> list2(kCurrentLargestDerivedElementSize);
+    list2.allocateAndConstruct<SimpleDerivedElementConstructMagicNumberTwo>();
+    list2.allocateAndConstruct<SimpleDerivedElementConstructMagicNumberThree>();
+
+    SimpleDerivedElement* preSwapList1Front = list1.front();
+
+    EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementOne, list1.front()->getValue());
+    EXPECT_EQ(1u, list1.size());
+    EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementTwo, list2.front()->getValue());
+    EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementThree, list2.back()->getValue());
+    EXPECT_EQ(2u, list2.size());
+
+    list2.swap(list1);
+
+    EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementTwo, list1.front()->getValue());
+    EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementThree, list1.back()->getValue());
+    EXPECT_EQ(2u, list1.size());
+    EXPECT_EQ(kMagicNumberToUseForSimpleDerivedElementOne, list2.front()->getValue());
+    EXPECT_EQ(1u, list2.size());
+
+    // Ensure pointers are still valid after swapping.
+    EXPECT_EQ(preSwapList1Front, list2.front());
+}
+
 } // namespace
 } // namespace blink