Don't initialize ICU replacement character for UTF-32 encodings

third_party/WebKit/Source/wtf/text/TextCodecICUTest.cpp

 // 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 "wtf/text/TextCodecICU.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
+#include "wtf/Vector.h"
 #include "wtf/text/CharacterNames.h"
 
 namespace WTF {
 
 TEST(TextCodecICUTest, IgnorableCodePoint) {
   TextEncoding iso2022jp("iso-2022-jp");
   std::unique_ptr<TextCodec> codec = TextCodecICU::create(iso2022jp, nullptr);
   Vector<UChar> source;
   source.append('a');
   source.append(zeroWidthJoinerCharacter);
   CString encoded =
       codec->encode(source.data(), source.size(), EntitiesForUnencodables);
   EXPECT_STREQ("a&#8205;", encoded.data());
 }
+
+TEST(TextCodecICUTest, UTF32AndQuestionMarks) {
+  Vector<String> aliases;
+  Vector<CString> results;
+
+  const UChar poo[] = {0xd83d, 0xdca9};  // U+1F4A9 PILE OF POO
+
+  aliases.append("UTF-32");
+  results.append("\xFF\xFE\x00\x00\xA9\xF4\x01\x00");
+
+  aliases.append("UTF-32LE");
+  results.append("\xA9\xF4\x01\x00");
+
+  aliases.append("UTF-32BE");
+  results.append("\x00\x01\xF4\xA9");
+
+  ASSERT_EQ(aliases.size(), results.size());
+  for (unsigned i = 0; i < aliases.size(); ++i) {
+    const String& alias = aliases[i];
+    const CString& expected = results[i];
+
+    TextEncoding encoding(alias);
+    std::unique_ptr<TextCodec> codec = TextCodecICU::create(encoding, nullptr);
+    {
+      const UChar* data = nullptr;
+      CString encoded = codec->encode(data, 0, QuestionMarksForUnencodables);
+      EXPECT_STREQ("", encoded.data());
+    }
+    {
+      CString encoded = codec->encode(poo, WTF_ARRAY_LENGTH(poo),
+                                      QuestionMarksForUnencodables);
+      EXPECT_STREQ(expected.data(), encoded.data());
+    }
+  }
 }
+}