Workaround for setComposition styling clobber

third_party/WebKit/Source/core/editing/InputMethodControllerTest.cpp

 // Copyright 2014 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/editing/InputMethodController.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
 #include "core/dom/Range.h"
 #include "core/editing/Editor.h"
@@ skipping 97 matching lines @@
     underlines.append(CompositionUnderline(0, 5, Color(255, 0, 0), false, 0));
     controller().setCompositionFromExistingText(underlines, 0, 5);
 
     Range* range = controller().compositionRange();
     EXPECT_EQ(0, range->startOffset());
     EXPECT_EQ(5, range->endOffset());
 
     PlainTextRange plainTextRange(PlainTextRange::create(*div, *range));
     EXPECT_EQ(0u, plainTextRange.start());
     EXPECT_EQ(5u, plainTextRange.end());
+
+    controller().setComposition(String("hellobar"), underlines, 8, 8);
+    range = controller().compositionRange();
+    EXPECT_EQ(0, range->startOffset());
+    EXPECT_EQ(8, range->endOffset());
+}
+
+TEST_F(InputMethodControllerTest, SetCompositionKeepingStyle)
+{
+    Element* div = insertHTMLElement(
+        "<div id='sample' contenteditable='true'><b>he</b>llo</div>", "sample");
+
+    Vector<CompositionUnderline> underlines;
+    underlines.append(CompositionUnderline(0, 5, Color(255, 0, 0), false, 0));
+    controller().setCompositionFromExistingText(underlines, 0, 5);
+
+    controller().setComposition(String("hell"), underlines, 4, 4);
+    EXPECT_STREQ("<b>he</b>ll", div->innerHTML().utf8().data());
+
+    controller().setComposition(String("hello"), underlines, 5, 5);
+    EXPECT_STREQ("<b>he</b>llo", div->innerHTML().utf8().data());

[aelias_OOO_until_Jul13, 2016/09/28 23:58:29]

Please add another test case for backspace.

[yabinh, 2016/10/11 01:42:23]

Line#134 is for backspace(from "hello" to "hell").

+}
+
+TEST_F(InputMethodControllerTest, SetCompositionWithMultiCodeTextKeepingStyle)
+{
+    // U+1F3E0 = 0xF0 0x9F 0x8F 0xA0 (UTF8). It's an emoji character with
+    // surrogate pairs.
+    Element* div = insertHTMLElement(
+        "<div id='sample' contenteditable='true'><b>&#x1f3e0</b></div>", "sample");
+    Vector<CompositionUnderline> underlines;
+    underlines.append(CompositionUnderline(0, 2, Color(255, 0, 0), false, 0));
+    controller().setCompositionFromExistingText(underlines, 0, 2);
+
+    // 0xF0 0x9F 0x8F 0xAB is also an emoji character with surrogate pairs.
+    controller().setComposition(String::fromUTF8("\xF0\x9F\x8F\xAB"), underlines, 2, 2);
+    EXPECT_STREQ("<b>\xF0\x9F\x8F\xAB</b>", div->innerHTML().utf8().data());
+
+    controller().setComposition(String::fromUTF8("\xF0\x9F\x8F\xA0"), underlines, 2, 2);
+    EXPECT_STREQ("<b>\xF0\x9F\x8F\xA0</b>", div->innerHTML().utf8().data());
+
+    // U+0C03 = 0xE0 0xB0 0x83 (UTF8), a telugu character with 1 code point.
+    div = insertHTMLElement(
+        "<div id='sample' contenteditable='true'><b>&#xc03</b></div>", "sample");
+    controller().setCompositionFromExistingText(underlines, 0, 1);
+
+    // 0xE0 0xB0 0x83 0xE0 0xB0 0x83, a telugu character with 2 code points in
+    // 1 grapheme cluster.
+    controller().setComposition(String::fromUTF8("\xE0\xB0\x83\xE0\xB0\x83"), underlines, 2, 2);
+    EXPECT_STREQ("<b>\xE0\xB0\x83\xE0\xB0\x83</b>", div->innerHTML().utf8().data());
+
+    controller().setComposition(String::fromUTF8("\xE0\xB0\x83"), underlines, 1, 1);

[yabinh, 2016/09/27 12:46:47]

Note that if we use code point to decide the common prefix length, this test
will not pass. The reason is that, for now, we can only select (and delete) by
grapheme cluster. we are not able to delete the second "\xE0\xB0\x83".

+    EXPECT_STREQ("<b>\xE0\xB0\x83</b>", div->innerHTML().utf8().data());
 }
 
 TEST_F(InputMethodControllerTest, SelectionOnConfirmExistingText)
 {
     insertHTMLElement(
         "<div id='sample' contenteditable='true'>hello world</div>", "sample");
 
     Vector<CompositionUnderline> underlines;
     underlines.append(CompositionUnderline(0, 5, Color(255, 0, 0), false, 0));
     controller().setCompositionFromExistingText(underlines, 0, 5);
@@ skipping 350 matching lines @@
     Vector<CompositionUnderline> underlines;
     underlines.append(CompositionUnderline(0, 5, Color(255, 0, 0), false, 0));
     editable->focus();
 
     document().setTitle(emptyString());
     controller().setComposition("n", underlines, 0, 1);
     EXPECT_STREQ("beforeinput.data:n;input.data:n;", document().title().utf8().data());
 
     document().setTitle(emptyString());
     controller().setComposition("ni", underlines, 0, 1);
-    EXPECT_STREQ("beforeinput.data:ni;input.data:ni;", document().title().utf8().data());
+    EXPECT_STREQ("beforeinput.data:i;input.data:i;", document().title().utf8().data());
 
     document().setTitle(emptyString());
     controller().finishComposingText(InputMethodController::KeepSelection);
     EXPECT_STREQ("beforeinput.data:ni;input.data:ni;", document().title().utf8().data());
 }
 
 } // namespace blink