Create PaintChunk and begin writing code to build paint chunks.

third_party/WebKit/Source/platform/graphics/paint/PaintChunkerTest.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/paint/PaintChunker.h"
+
+#include "platform/RuntimeEnabledFeatures.h"
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+using testing::ElementsAre;
+
+namespace blink {
+namespace {
+
+static PaintProperties samplePaintProperties() { return PaintProperties(); }
+
+class PaintChunkerTest : public testing::Test {
+protected:
+    void SetUp() override
+    {
+        RuntimeEnabledFeatures::setSlimmingPaintV2Enabled(true);
+    }
+
+    void TearDown() override
+    {
+        m_featuresBackup.restore();
+    }
+
+private:
+    RuntimeEnabledFeatures::Backup m_featuresBackup;
+};
+
+TEST_F(PaintChunkerTest, Empty)
+{
+    Vector<PaintChunk> chunks = PaintChunker().releasePaintChunks();
+    ASSERT_TRUE(chunks.isEmpty());
+}
+
+TEST_F(PaintChunkerTest, SingleNonEmptyRange)
+{
+    PaintChunker chunker;
+    chunker.updateCurrentPaintProperties(samplePaintProperties());
+    chunker.incrementDisplayItemIndex();
+    chunker.incrementDisplayItemIndex();
+    Vector<PaintChunk> chunks = chunker.releasePaintChunks();
+
+    EXPECT_THAT(chunks, ElementsAre(
+        PaintChunk(0, 2, samplePaintProperties())));
+}
+
+TEST_F(PaintChunkerTest, SamePropertiesTwiceCombineIntoOneChunk)
+{
+    PaintChunker chunker;
+    chunker.updateCurrentPaintProperties(samplePaintProperties());
+    chunker.incrementDisplayItemIndex();
+    chunker.incrementDisplayItemIndex();
+    chunker.updateCurrentPaintProperties(samplePaintProperties());
+    chunker.incrementDisplayItemIndex();
+    Vector<PaintChunk> chunks = chunker.releasePaintChunks();
+
+    EXPECT_THAT(chunks, ElementsAre(
+        PaintChunk(0, 3, samplePaintProperties())));
+}
+
+TEST_F(PaintChunkerTest, CanRewindDisplayItemIndex)
+{
+    PaintChunker chunker;
+    chunker.updateCurrentPaintProperties(samplePaintProperties());
+    chunker.incrementDisplayItemIndex();
+    chunker.incrementDisplayItemIndex();
+    chunker.decrementDisplayItemIndex();
+    chunker.incrementDisplayItemIndex();
+    Vector<PaintChunk> chunks = chunker.releasePaintChunks();
+
+    EXPECT_THAT(chunks, ElementsAre(
+        PaintChunk(0, 2, samplePaintProperties())));
+}
+
+// TODO(jbroman): Add more tests one it is possible for there to be two distinct
+// PaintProperties.
+
+} // namespace
+} // namespace blink