diff -r 000000000000 -r 6474c204b198 xpcom/tests/TestStringAPI.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/tests/TestStringAPI.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,209 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <stdio.h>
+#include "nsStringAPI.h"
+
+#define CHECK(x) \
+  _doCheck(x, #x, __LINE__)
+
+int _doCheck(bool cond, const char* msg, int line) {
+  if (cond) return 0;
+  fprintf(stderr, "FAIL: line %d: %s\n", line, msg);
+  return 1;
+}
+
+int testEmpty() {
+  nsString s;
+  return CHECK(0 == s.Length()) +
+         CHECK(s.IsEmpty());
+}
+
+int testAccess() {
+  nsString s;
+  s.Assign(NS_LITERAL_STRING("hello"));
+  int res = CHECK(5 == s.Length()) +
+            CHECK(s.EqualsLiteral("hello"));
+  const char16_t *it, *end;
+  int len = s.BeginReading(&it, &end);
+  res += CHECK(5 == len);
+  res += CHECK(char16_t('h') == it[0]) +
+         CHECK(char16_t('e') == it[1]) +
+         CHECK(char16_t('l') == it[2]) +
+         CHECK(char16_t('l') == it[3]) +
+         CHECK(char16_t('o') == it[4]) +
+         CHECK(it + len == end);
+  res += CHECK(s[0] == s.First());
+  for (int i = 0; i < len; ++i) {
+    res += CHECK(s[i] == it[i]);
+    res += CHECK(s[i] == s.CharAt(i));
+  }
+  res += CHECK(it == s.BeginReading());
+  res += CHECK(end == s.EndReading());
+  return res;
+}
+
+int testWrite() {
+  nsString s(NS_LITERAL_STRING("xyzz"));
+  char16_t *begin, *end;
+  int res = CHECK(4 == s.Length());
+  uint32_t len = s.BeginWriting(&begin, &end, 5);
+  res += CHECK(5 == s.Length()) +
+         CHECK(5 == len) +
+         CHECK(end == begin + 5) +
+         CHECK(begin == s.BeginWriting()) +
+         CHECK(end == s.EndWriting());
+  begin[4] = char16_t('y');
+  res += CHECK(s.Equals(NS_LITERAL_STRING("xyzzy")));
+  s.SetLength(4);
+  res += CHECK(4 == s.Length()) +
+         CHECK(s.Equals(NS_LITERAL_STRING("xyzz"))) +
+         CHECK(!s.Equals(NS_LITERAL_STRING("xyzzy"))) +
+         CHECK(!s.IsEmpty());
+  s.Truncate();
+  res += CHECK(0 == s.Length()) +
+         CHECK(s.IsEmpty());
+  const char16_t sample[] = { 's', 'a', 'm', 'p', 'l', 'e', '\0' };
+  s.Assign(sample);
+  res += CHECK(s.EqualsLiteral("sample"));
+  s.Assign(sample, 4);
+  res += CHECK(s.EqualsLiteral("samp"));
+  s.Assign(char16_t('q'));
+  res += CHECK(s.EqualsLiteral("q"));
+  return res;
+}
+
+int testFind() {
+  nsString str_haystack;
+  nsString str_needle;
+  str_needle.AssignLiteral("world");
+
+  int32_t ret = 0;
+  ret += CHECK(-1 == str_haystack.Find("world"));
+  ret += CHECK(-1 == str_haystack.Find(str_needle));
+
+  str_haystack.AssignLiteral("hello world hello world hello");
+  ret += CHECK( 6 == str_haystack.Find("world"));
+  ret += CHECK( 6 == str_haystack.Find(str_needle));
+  ret += CHECK(-1 == str_haystack.Find("world", 20, false));
+  ret += CHECK(-1 == str_haystack.Find(str_needle, 20));
+  ret += CHECK(18 == str_haystack.Find("world", 12, false));
+  ret += CHECK(18 == str_haystack.Find(str_needle, 12));
+
+  nsCString cstr_haystack;
+  nsCString cstr_needle;
+  cstr_needle.AssignLiteral("world");
+  
+  ret += CHECK(-1 == cstr_haystack.Find("world"));
+  ret += CHECK(-1 == cstr_haystack.Find(cstr_needle));
+
+  cstr_haystack.AssignLiteral("hello world hello world hello");
+  ret += CHECK( 6 == cstr_haystack.Find("world"));
+  ret += CHECK( 6 == cstr_haystack.Find(cstr_needle));
+  ret += CHECK(-1 == cstr_haystack.Find(cstr_needle, 20));
+  ret += CHECK(18 == cstr_haystack.Find(cstr_needle, 12));
+  ret += CHECK( 6 == cstr_haystack.Find("world", 5));
+
+  return ret;
+}
+
+int testVoid() {
+  nsString s;
+  int ret = CHECK(!s.IsVoid());
+  s.SetIsVoid(false);
+  ret += CHECK(!s.IsVoid());
+  s.SetIsVoid(true);
+  ret += CHECK(s.IsVoid());
+  s.SetIsVoid(false);
+  ret += CHECK(!s.IsVoid());
+  s.SetIsVoid(true);
+  s.AssignLiteral("hello");
+  ret += CHECK(!s.IsVoid());
+  return ret;
+}
+
+int testRFind() {
+  int32_t ret = 0;
+
+  // nsString.RFind
+  nsString str_haystack;
+  nsString str_needle;
+  str_needle.AssignLiteral("world");
+
+  ret += CHECK(-1 == str_haystack.RFind(str_needle));
+  ret += CHECK(-1 == str_haystack.RFind("world"));
+
+  str_haystack.AssignLiteral("hello world hElLo woRlD");
+
+  ret += CHECK( 6 == str_haystack.RFind(str_needle));
+  ret += CHECK( 6 == str_haystack.RFind(str_needle, -1));
+  ret += CHECK( 6 == str_haystack.RFind(str_needle, 17));
+  ret += CHECK( 6 == str_haystack.RFind("world", false));
+  ret += CHECK(18 == str_haystack.RFind("world", true));
+  ret += CHECK( 6 == str_haystack.RFind("world", -1, false));
+  ret += CHECK(18 == str_haystack.RFind("world", -1, true));
+  ret += CHECK( 6 == str_haystack.RFind("world", 17, false));
+  ret += CHECK( 0 == str_haystack.RFind("hello", 0, false));
+  ret += CHECK(18 == str_haystack.RFind("world", 19, true));
+  ret += CHECK(18 == str_haystack.RFind("world", 22, true));
+  ret += CHECK(18 == str_haystack.RFind("world", 23, true));
+
+  // nsCString.RFind
+  nsCString cstr_haystack;
+  nsCString cstr_needle;
+  cstr_needle.AssignLiteral("world");
+
+  ret += CHECK(-1 == cstr_haystack.RFind(cstr_needle));
+  ret += CHECK(-1 == cstr_haystack.RFind("world"));
+  
+  cstr_haystack.AssignLiteral("hello world hElLo woRlD");
+
+  ret += CHECK( 6 == cstr_haystack.RFind(cstr_needle));
+  ret += CHECK( 6 == cstr_haystack.RFind(cstr_needle, -1));
+  ret += CHECK( 6 == cstr_haystack.RFind(cstr_needle, 17));
+  ret += CHECK( 6 == cstr_haystack.RFind("world", 5));
+  ret += CHECK( 0 == cstr_haystack.RFind(nsDependentCString("hello"), 0));
+
+  return ret;
+}
+
+int testCompressWhitespace() {
+  int32_t ret = 0;
+
+  // CompressWhitespace utility function
+  nsString s;
+
+  s.AssignLiteral("     ");
+  CompressWhitespace(s);
+  ret += CHECK(s.EqualsLiteral(""));
+
+  s.AssignLiteral("  no more  leading spaces");
+  CompressWhitespace(s);
+  ret += CHECK(s.EqualsLiteral("no more leading spaces"));
+
+  s.AssignLiteral("no    more trailing spaces ");
+  CompressWhitespace(s);
+  ret += CHECK(s.EqualsLiteral("no more trailing spaces"));
+
+  s.AssignLiteral("   hello one    2         three    45        ");
+  CompressWhitespace(s);
+  ret += CHECK(s.EqualsLiteral("hello one 2 three 45"));
+
+  return ret;
+}
+
+int main() {
+  int rv = 0;
+  rv += testEmpty();
+  rv += testAccess();
+  rv += testWrite();
+  rv += testFind();
+  rv += testVoid();
+  rv += testRFind();
+  rv += testCompressWhitespace();
+  if (0 == rv) {
+    fprintf(stderr, "PASS: StringAPI tests\n");
+  }
+  return rv;
+}