chromium/third_party/blink/web_tests/fast/css/lang-selector-empty-attribute.xhtml

<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <style type="text/css">
      span {background: white;display:none}
      span:lang(de) {background: red}
    </style>
    <script>
      function log(message) {
        document.getElementById("console").innerHTML += message;
      }

      function test() {
        if (window.testRunner)
            testRunner.dumpAsText();

        var i = document.getElementById("emptyLang");
        if (document.defaultView.getComputedStyle(i, null).getPropertyValue('background-color') != "rgb(255, 255, 255)") {
            log("FAILURE");
            return;
        }
        var i2 = document.getElementById("emptyXmlLang");
        if (document.defaultView.getComputedStyle(i2, null).getPropertyValue('background-color') != "rgb(255, 255, 255)") {
            log("FAILURE");
            return;
       }
        var i3 = document.getElementById("noLang");
        if (document.defaultView.getComputedStyle(i3, null).getPropertyValue('background-color') != "rgb(255, 0, 0)") {
            log("FAILURE");
            return;
        }
        log("SUCCESS");
      }
    </script>
  </head>
  <body onload="test()">
    <p>Tests if empty language declarations are supported</p>
    <p xml:lang="de">
      <span lang="" id="emptyLang"/>
      <span xml:lang="" id="emptyXmlLang"/>
      <span id="noLang"/>
    </p>
    <div id="console"></div>
  </body>
</html>