WIP - Rough draft of style observation in style of apply hooks.

Source/core/style/StyleObserverTest.cpp

Index: Source/core/style/StyleObserverTest.cpp
diff --git a/Source/core/style/StyleObserverTest.cpp b/Source/core/style/StyleObserverTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..604abbaab638af57332435435ac7804b5fd70bd7
--- /dev/null
+++ b/Source/core/style/StyleObserverTest.cpp
@@ -0,0 +1,110 @@
+// 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 "core/style/StyleObserver.h"
+
+#include "core/dom/Document.h"
+#include "core/dom/Element.h"
+#include "core/frame/FrameView.h"
+#include "core/style/ComputedStyle.h"
+#include "core/testing/DummyPageHolder.h"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
+using ::testing::_;
+
+namespace blink {
+
+class StyleObserverTest : public ::testing::Test {
+protected:
+    StyleObserverTest()
+        : pageHolder(DummyPageHolder::create())
+        , document(pageHolder->document())
+    {
+        setHTML("<div id='first'></div><div id='second'></div>");
+        layoutAndStyle();
+    }
+
+    void setHTML(const char* htmlContent)
+    {
+        document.documentElement()->setInnerHTML(String::fromUTF8(htmlContent), ASSERT_NO_EXCEPTION);
+    }
+
+    void layoutAndStyle()
+    {
+        document.view()->updateAllLifecyclePhases();
+    }
+
+    OwnPtr<DummyPageHolder> pageHolder;
+    Document& document;
+    TrackExceptionState exceptionState;
+};
+
+class MockStyleObserver: public StyleObserver {
+public:
+    MOCK_METHOD3(onStyleChanged, void(const Element*, const ComputedStyle*, const ComputedStyle*));
+};
+
+TEST_F(StyleObserverTest, MultipleObserversSingleChange)
+{
+    EXPECT_EQ(false, document.hasStyleObserver());
+
+    MockStyleObserver observer1;
+    MockStyleObserver observer2;
+
+    document.registerStyleObserver(&observer1);
+    EXPECT_EQ(true, document.hasStyleObserver());
+
+    document.registerStyleObserver(&observer2);
+    EXPECT_EQ(true, document.hasStyleObserver());
+
+    EXPECT_CALL(observer1, onStyleChanged(_, _, _)).Times(1);
+    EXPECT_CALL(observer2, onStyleChanged(_, _, _)).Times(1);
+
+    document.getElementById("first")->setAttribute("style", "border: 2px solid;", exceptionState);
+    layoutAndStyle();
+    ::testing::Mock::VerifyAndClearExpectations(&observer1);
+    ::testing::Mock::VerifyAndClearExpectations(&observer2);
+
+    document.unregisterStyleObserver(&observer1);
+    EXPECT_EQ(true, document.hasStyleObserver());
+
+    EXPECT_CALL(observer1, onStyleChanged(_, _, _)).Times(0);
+    EXPECT_CALL(observer2, onStyleChanged(_, _, _)).Times(1);
+    document.getElementById("first")->setAttribute("style", "border: 5px solid;", exceptionState);
+    layoutAndStyle();
+    ::testing::Mock::VerifyAndClearExpectations(&observer1);
+    ::testing::Mock::VerifyAndClearExpectations(&observer2);
+
+    document.unregisterStyleObserver(&observer2);
+    EXPECT_EQ(false, document.hasStyleObserver());
+
+    EXPECT_CALL(observer1, onStyleChanged(_, _, _)).Times(0);
+    EXPECT_CALL(observer2, onStyleChanged(_, _, _)).Times(0);
+    document.getElementById("first")->setAttribute("style", "border: 10px solid;", exceptionState);
+    layoutAndStyle();
+    ::testing::Mock::VerifyAndClearExpectations(&observer1);
+    ::testing::Mock::VerifyAndClearExpectations(&observer2);
+}
+
+TEST_F(StyleObserverTest, SingleObserverMultipleChanges)
+{
+    MockStyleObserver observer;
+    document.registerStyleObserver(&observer);
+    const Element* first = document.getElementById("first");
+    const Element* second = document.getElementById("second");
+
+    EXPECT_CALL(observer, onStyleChanged(first, _, _)).Times(1);
+    EXPECT_CALL(observer, onStyleChanged(second, _, _)).Times(1);
+
+    document.getElementById("first")->setAttribute("style", "border: 2px solid;", exceptionState);
+    document.getElementById("second")->setAttribute("style", "border: 2px solid;", exceptionState);
+
+    layoutAndStyle();
+    ::testing::Mock::VerifyAndClearExpectations(&observer);
+}
+
+} // namespace blink