Bug 1534878 - xpcom: Re-enable NonASCII16 UTF-16 string tests. r=hsivonen

The NonASCII16 test function was removed in bug 1402247 but the NonASCII16_helper() function was not:

https://hg.mozilla.org/mozilla-central/rev/4ef0f163fdeb

xpcom/tests/gtest/TestUTF.cpp:119:6 [-Wmissing-prototypes] no previous prototype for function 'NonASCII16_helper'

Differential Revision: https://phabricator.services.mozilla.com/D23267

--HG--
extra : rebase_source : c53118479acc6ea866dafb04617bfb2706dddb2b
extra : source : de3a70ccef6c09d0d317c7b4b5c1f8a2f93d78c7

xpcom/tests/gtest/TestUTF.cpp

@@ -116,7 +116,7 @@ TEST(UTF, Hash16) {
  * This tests the handling of a non-ascii character at various locations in a
  * UTF-16 string that is being converted to UTF-8.
  */
-void NonASCII16_helper(const size_t aStrSize) {
+static void NonASCII16_helper(const size_t aStrSize) {
   const size_t kTestSize = aStrSize;
   const size_t kMaxASCII = 0x80;
   const char16_t kUTF16Char = 0xC9;
@@ -154,7 +154,7 @@ void NonASCII16_helper(const size_t aStrSize) {
     // First add the leading ASCII chars.
     expected.Append(asciiCString.BeginReading(), i);
 
-    // Now append the UTF-8 surrogate pair we expect the UTF-16 unicode char to
+    // Now append the UTF-8 pair we expect the UTF-16 unicode char to
     // be converted to.
     for (auto& c : kUTF8Surrogates) {
       expected.Append(c);
@@ -167,6 +167,15 @@ void NonASCII16_helper(const size_t aStrSize) {
   }
 }
 
+TEST(UTF, NonASCII16) {
+  // Test with various string sizes to catch any special casing.
+  NonASCII16_helper(1);
+  NonASCII16_helper(8);
+  NonASCII16_helper(16);
+  NonASCII16_helper(32);
+  NonASCII16_helper(512);
+}
+
 TEST(UTF, UTF8CharEnumerator) {
   const char* p =
       "\x61\xC0\xC2\xC2\x80\xE0\x80\x80\xE0\xA0\x80\xE1\x80\x80\xED\xBF\xBF\xED"