text: function shouldBe(actual, expected) {
      if (actual !== expected)
          throw new Error('bad value: ' + actual);
  }
  
  function isLowSurrogate(code)
  {
      return code >= 0xDC00 && code <= 0xDFFF;
  }
  
  function isHighSurrogate(code)
  {
      return code >= 0xD800 && code <= 0xDBFF;
  }
  
  function isSurrogate(code)
  {
      return isLowSurrogate(code) || isHighSurrogate(code);
  }
  
  for (var i = 256; i < 0xffff; ++i) {
      if (isSurrogate(i))
          continue;
      var ch = String.fromCharCode(i);
      shouldBe(decodeURIComponent(encodeURIComponent(ch)), ch);
      shouldBe(decodeURI(encodeURI(ch)), ch);
      shouldBe(unescape(escape(ch)), ch);
  }
  