layout/style/test/test_rules_out_of_sheets.html

   1 <!DOCTYPE HTML>
   2 <html>
   3 <!--
   4 https://bugzilla.mozilla.org/show_bug.cgi?id=634373
   5 -->
   6 <head>
   7   <title>Test for Bug 634373</title>
   8   <script src="/tests/SimpleTest/SimpleTest.js"></script>
   9   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
  10 </head>
  11 <body>
  12 <a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=634373">Mozilla Bug 634373</a>
  13 <p id="display"></p>
  14 <div id="content" style="display: none">
  15
  16 </div>
  17 <pre id="test">
  18 <script type="application/javascript">
  19
  20 /** Test for Bug 634373 **/
  21
  22 function make_rule_and_remove_sheet(text, getter) {
  23   var style = document.createElement("style");
  24   style.setAttribute("type", "text/css");
  25   style.appendChild(document.createTextNode(text));
  26   document.head.appendChild(style);
  27   var result = style.sheet.cssRules[0];
  28   if (getter) {
  29     result = getter(result);
  30   }
  31   document.head.removeChild(style);
  32   style = null;
  33   SpecialPowers.DOMWindowUtils.garbageCollect();
  34   return result;
  35 }
  36
  37 var gDisplayCS = getComputedStyle(document.getElementById("display"), "");
  38
  39 function keep_rule_alive_by_matching(rule) {
  40   // It's the caller's job to guarantee that the rule matches a p.
  41   // This just causes a style flush, which in turn keeps the rule alive
  42   // until the next style flush.
  43   var color = gDisplayCS.color;
  44   return rule;
  45 }
  46
  47 function get_rule_and_child(rule) {
  48   return [rule, rule.cssRules[0]];
  49 }
  50
  51 function get_only_child(rule) {
  52   return rule.cssRules[0];
  53 }
  54
  55 var rule;
  56
  57 // In this case, the rule goes away immediately, so we're testing
  58 // the DOM wrapper's handling of a null rule, rather than the rule's
  59 // handling of a null sheet.
  60 rule = make_rule_and_remove_sheet("p { color: blue }");
  61 rule.style.color = "";
  62 try {
  63   rule.style.color = "fuchsia";
  64 } catch(ex) {}
  65
  66 rule = make_rule_and_remove_sheet("p { color: blue }",
  67                                   keep_rule_alive_by_matching);
  68 try {
  69   rule.style.color = "";
  70 } catch(ex) {}
  71 try {
  72   rule.style.color = "fuchsia";
  73 } catch(ex) {}
  74
  75 rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",
  76                                    get_rule_and_child);
  77 rule[1].style.color = "";
  78 try {
  79   rule[1].style.color = "fuchsia";
  80 } catch(ex) {}
  81
  82 // In this case, the rule goes away immediately, so we're testing
  83 // the DOM wrapper's handling of a null rule, rather than the rule's
  84 // handling of a null sheet.
  85 rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",
  86                                    get_only_child);
  87 rule.style.color = "";
  88 try {
  89   rule.style.color = "fuchsia";
  90 } catch(ex) {}
  91
  92 rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",
  93                                   function(ruleInner) {
  94                                     return keep_rule_alive_by_matching(
  95                                              get_only_child(ruleInner));
  96                                   });
  97 try {
  98   rule.style.color = "";
  99 } catch(ex) {}
 100 try {
 101   rule.style.color = "fuchsia";
 102 } catch(ex) {}
 103
 104 rule = make_rule_and_remove_sheet("@keyframes a { from { color: blue } }");
 105 rule.appendRule("from { color: fuchsia}");
 106 rule.deleteRule("from");
 107 rule.name = "b";
 108 rule.cssRules[0].keyText = "50%";
 109
 110 ok(true, "didn't crash");
 111
 112 </script>
 113 </pre>
 114 </body>
 115 </html>