gecko/layout/style/test/test_variables.html

<!DOCTYPE type>
<title>Assorted CSS variable tests</title>
<script src="/MochiKit/MochiKit.js"></script>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" href="/tests/SimpleTest/test.css" type="text/css">

<style id="test1">
</style>

<style id="test2">
</style>

<style id="test3">
</style>

<style id="test4">
</style>

<div id="t4"></div>

<script>
var tests = [
  function() {
    // https://bugzilla.mozilla.org/show_bug.cgi?id=773296#c121
    var test1 = document.getElementById("test1");
    test1.textContent = "p { --a:123!important; }";
    var declaration = test1.sheet.cssRules[0].style;
    declaration.cssText;
    declaration.setProperty("color", "black");
    is(declaration.getPropertyValue("--a"), "123");
  },

  function() {
    // https://bugzilla.mozilla.org/show_bug.cgi?id=773296#c121
    var test2 = document.getElementById("test2");
    test2.textContent = "p { --a: a !important; }";
    var declaration = test2.sheet.cssRules[0].style;
    is(declaration.getPropertyPriority("--a"), "important");
  },

  function() {
    // https://bugzilla.mozilla.org/show_bug.cgi?id=955913
    var test3 = document.getElementById("test3");
    test3.textContent = "p { border-left-style: inset; padding: 1px; --decoration: line-through; }";
    var declaration = test3.sheet.cssRules[0].style;
    is(declaration[declaration.length - 1], "--decoration");
  },

  function() {
    // https://bugzilla.mozilla.org/show_bug.cgi?id=959973
    var test4 = document.getElementById("test4");
    test4.textContent = "#t4 { background-image: var(--a); }";

    var element = document.getElementById("t4");
    var path = window.location.pathname;
    var currentDir = path.substring(0, path.lastIndexOf('/'));
    var imageURL = "http://mochi.test:8888" + currentDir + "/image.png";

    is(window.getComputedStyle(element).getPropertyValue("background-image"), "url(\"" + imageURL +"\")");
  },
];

function prepareTest() {
  // Load an external style sheet for test 4.
  var e = document.createElement("link");
  e.addEventListener("load", runTest);
  e.setAttribute("rel", "stylesheet");
  e.setAttribute("href", "support/external-variable-url.css");
  document.head.appendChild(e);
}

function runTest() {
  tests.forEach(function(fn) { fn(); });
  SimpleTest.finish();
}

SimpleTest.waitForExplicitFinish();
SpecialPowers.pushPrefEnv({ set: [["layout.css.variables.enabled", true ]] },
                          prepareTest);
</script>