FirstMeaningfulPaint UMA

third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp

Index: third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp
diff --git a/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp b/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..8ed58e4aca301fdd7262b1c4101996710234b67e
--- /dev/null
+++ b/third_party/WebKit/Source/core/paint/FirstMeaningfulPaintDetectorTest.cpp
@@ -0,0 +1,101 @@
+// Copyright 2016 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 "core/paint/FirstMeaningfulPaintDetector.h"
+
+#include "core/paint/PaintTiming.h"
+#include "core/testing/DummyPageHolder.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace blink {
+
+class FirstMeaningfulPaintDetectorTest : public testing::Test {
+protected:
+    void SetUp() override
+    {
+        m_dummyPageHolder = DummyPageHolder::create(IntSize(800, 600));
+        s_timeElapsed = 0.0;
+        m_originalTimeFunction = setTimeFunctionsForTesting(returnMockTime);
+    }
+
+    void TearDown() override
+    {
+        setTimeFunctionsForTesting(m_originalTimeFunction);
+    }
+
+    Document& document() { return m_dummyPageHolder->document(); }
+    PaintTiming& paintTiming() { return PaintTiming::from(document()); }
+    FirstMeaningfulPaintDetector& detector() { return paintTiming().firstMeaningfulPaintDetector(); }
+
+    void simulateLayoutAndPaint(int newElements)
+    {
+        StringBuilder builder;
+        for (int i = 0; i < newElements; i++)
+            builder.append("<span>a</span>");
+        document().write(builder.toString());
+        document().updateStyleAndLayout();
+        detector().notifyPaint();
+    }
+
+    void simulateNetworkStable()
+    {
+        detector().networkStableTimerFired(nullptr);
+    }
+
+private:
+    static double returnMockTime()
+    {
+        s_timeElapsed += 1.0;
+        return s_timeElapsed;
+    }
+
+    std::unique_ptr<DummyPageHolder> m_dummyPageHolder;
+    TimeFunction m_originalTimeFunction;
+    static double s_timeElapsed;
+};
+
+double FirstMeaningfulPaintDetectorTest::s_timeElapsed;
+
+TEST_F(FirstMeaningfulPaintDetectorTest, NoFirstPaint)
+{
+    simulateLayoutAndPaint(1);
+    simulateNetworkStable();
+    EXPECT_EQ(paintTiming().firstMeaningfulPaint(), 0.0);
+}
+
+TEST_F(FirstMeaningfulPaintDetectorTest, OneLayout)
+{
+    paintTiming().markFirstPaint();
+    simulateLayoutAndPaint(1);
+    double afterPaint = monotonicallyIncreasingTime();
+    EXPECT_EQ(paintTiming().firstMeaningfulPaint(), 0.0);
+    simulateNetworkStable();
+    EXPECT_GT(paintTiming().firstMeaningfulPaint(), paintTiming().firstPaint());
+    EXPECT_LT(paintTiming().firstMeaningfulPaint(), afterPaint);
+}
+
+TEST_F(FirstMeaningfulPaintDetectorTest, TwoLayoutsSignificantFirst)

[Charlie Harrison, 2016/08/09 16:27:33]

Seems like the second is significant here, not the first.

[Kunihiko Sakamoto, 2016/08/10 02:33:32]

Ooops, fixed.

+{
+    paintTiming().markFirstPaint();
+    simulateLayoutAndPaint(1);
+    double afterLayout1 = monotonicallyIncreasingTime();
+    simulateLayoutAndPaint(10);
+    double afterLayout2 = monotonicallyIncreasingTime();
+    simulateNetworkStable();
+    EXPECT_GT(paintTiming().firstMeaningfulPaint(), afterLayout1);
+    EXPECT_LT(paintTiming().firstMeaningfulPaint(), afterLayout2);
+}
+
+TEST_F(FirstMeaningfulPaintDetectorTest, TwoLayoutsSignificantSecond)

[Charlie Harrison, 2016/08/09 16:27:33]

Seems like the first is significant here, not the second.

[Kunihiko Sakamoto, 2016/08/10 02:33:32]

Done.

+{
+    paintTiming().markFirstPaint();
+    simulateLayoutAndPaint(10);
+    double afterLayout1 = monotonicallyIncreasingTime();
+    simulateLayoutAndPaint(1);
+    simulateNetworkStable();
+    EXPECT_GT(paintTiming().firstMeaningfulPaint(), paintTiming().firstPaint());
+    EXPECT_LT(paintTiming().firstMeaningfulPaint(), afterLayout1);
+}
+
+} // namespace blink