Introduce composed tree version of characterAfter()

Source/core/editing/VisibleUnitsTest.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 "core/editing/VisibleUnits.h"
 
 #include "core/editing/EditingTestBase.h"
 #include "core/editing/VisiblePosition.h"
 
@@ skipping 37 matching lines @@
     RefPtrWillBeRawPtr<Element> body = document().body();
     RefPtrWillBeRawPtr<Element> one = body->querySelector("#one", ASSERT_NO_EXCEPTION);
 
     IntRect boundsInDOMTree = absoluteCaretBoundsOf(createVisiblePosition(Position(one.get(), 0)));
     IntRect boundsInComposedTree = absoluteCaretBoundsOf(createVisiblePosition(PositionInComposedTree(one.get(), 0)));
 
     EXPECT_FALSE(boundsInDOMTree.isEmpty());
     EXPECT_EQ(boundsInDOMTree, boundsInComposedTree);
 }
 
+TEST_F(VisibleUnitsTest, characterAfter)
+{
+    const char* bodyContent = "<p id='host'><b id='one'>1</b><b id='two'>22</b></p><b id='three'>333</b>";
+    const char* shadowContent = "<b id='four'>4444</b><content select=#two></content><content select=#one></content><b id='five'>5555</b>";
+    setBodyContent(bodyContent);
+    setShadowContent(shadowContent, "host");
+    updateLayoutAndStyleForPainting();
+
+    RefPtrWillBeRawPtr<Element> one = document().getElementById("one");
+    RefPtrWillBeRawPtr<Element> two = document().getElementById("two");
+
+    EXPECT_EQ('2', characterAfter(createVisiblePositionInDOMTree(*one->firstChild(), 1)));
+    EXPECT_EQ('5', characterAfter(createVisiblePositionInComposedTree(*one->firstChild(), 1)));
+
+    EXPECT_EQ(0, characterAfter(createVisiblePositionInDOMTree(*two->firstChild(), 2)));
+    EXPECT_EQ('1', characterAfter(createVisiblePositionInComposedTree(*two->firstChild(), 2)));
+}
+
 TEST_F(VisibleUnitsTest, inSameLine)
 {
     const char* bodyContent = "<p id='host'>00<b id='one'>11</b><b id='two'>22</b>33</p>";
     const char* shadowContent = "<div><span id='s4'>44</span><content select=#two></content><br><span id='s5'>55</span><br><content select=#one></content><span id='s6'>66</span></div>";
     setBodyContent(bodyContent);
     RefPtrWillBeRawPtr<ShadowRoot> shadowRoot = setShadowContent(shadowContent, "host");
     updateLayoutAndStyleForPainting();
 
     RefPtrWillBeRawPtr<Element> body = document().body();
     RefPtrWillBeRawPtr<Element> one = body->querySelector("#one", ASSERT_NO_EXCEPTION);
@@ skipping 91 matching lines @@
     setBodyContent(bodyContent);
     updateLayoutAndStyleForPainting();
     RefPtrWillBeRawPtr<Element> sample1 = document().getElementById("sample1");
     RefPtrWillBeRawPtr<Element> sample2 = document().getElementById("sample2");
 
     EXPECT_FALSE(rendersInDifferentPosition(Position::afterNode(sample1->firstChild()), Position(sample2->firstChild(), 0)));
     EXPECT_FALSE(rendersInDifferentPosition(Position::lastPositionInNode(sample1->firstChild()), Position(sample2->firstChild(), 0)));
 }
 
 } // namespace blink