diff -r 000000000000 -r 6474c204b198 browser/devtools/styleinspector/test/browser_ruleview_override.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/styleinspector/test/browser_ruleview_override.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,146 @@
+/* vim: set ft=javascript ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test the display of overridden declarations in the rule-view
+
+let test = asyncTest(function*() {
+  yield addTab("data:text/html;charset=utf-8,browser_ruleview_override.js");
+  let {toolbox, inspector, view} = yield openRuleView();
+
+  yield simpleOverride(inspector, view);
+  yield partialOverride(inspector, view);
+  yield importantOverride(inspector, view);
+  yield disableOverride(inspector, view);
+});
+
+function* createTestContent(inspector, style) {
+  let onMutated = inspector.once("markupmutation");
+  let styleNode = addStyle(content.document, style);
+  content.document.body.innerHTML = '<div id="testid" class="testclass">Styled Node</div>';
+  yield onMutated;
+  yield selectNode("#testid", inspector);
+  return styleNode;
+}
+
+function* simpleOverride(inspector, view) {
+  let styleNode = yield createTestContent(inspector, '' +
+    '#testid {' +
+    '  background-color: blue;' +
+    '} ' +
+    '.testclass {' +
+    '  background-color: green;' +
+    '}');
+
+  let elementStyle = view._elementStyle;
+
+  let idRule = elementStyle.rules[1];
+  let idProp = idRule.textProps[0];
+  is(idProp.name, "background-color", "First ID prop should be background-color");
+  ok(!idProp.overridden, "ID prop should not be overridden.");
+
+  let classRule = elementStyle.rules[2];
+  let classProp = classRule.textProps[0];
+  is(classProp.name, "background-color", "First class prop should be background-color");
+  ok(classProp.overridden, "Class property should be overridden.");
+
+  // Override background-color by changing the element style.
+  let elementRule = elementStyle.rules[0];
+  elementRule.createProperty("background-color", "purple", "");
+  yield elementRule._applyingModifications;
+
+  let elementProp = elementRule.textProps[0];
+  is(classProp.name, "background-color", "First element prop should now be background-color");
+  ok(!elementProp.overridden, "Element style property should not be overridden");
+  ok(idProp.overridden, "ID property should be overridden");
+  ok(classProp.overridden, "Class property should be overridden");
+
+  styleNode.remove();
+}
+
+function* partialOverride(inspector, view) {
+  let styleNode = yield createTestContent(inspector, '' +
+    // Margin shorthand property...
+    '.testclass {' +
+    '  margin: 2px;' +
+    '}' +
+    // ... will be partially overridden.
+    '#testid {' +
+    '  margin-left: 1px;' +
+    '}');
+
+  let elementStyle = view._elementStyle;
+
+  let classRule = elementStyle.rules[2];
+  let classProp = classRule.textProps[0];
+  ok(!classProp.overridden,
+    "Class prop shouldn't be overridden, some props are still being used.");
+
+  for (let computed of classProp.computed) {
+    if (computed.name.indexOf("margin-left") == 0) {
+      ok(computed.overridden, "margin-left props should be overridden.");
+    } else {
+      ok(!computed.overridden, "Non-margin-left props should not be overridden.");
+    }
+  }
+
+  styleNode.remove();
+}
+
+function* importantOverride(inspector, view) {
+  let styleNode = yield createTestContent(inspector, '' +
+    // Margin shorthand property...
+    '.testclass {' +
+    '  background-color: green !important;' +
+    '}' +
+    // ... will be partially overridden.
+    '#testid {' +
+    '  background-color: blue;' +
+    '}');
+
+  let elementStyle = view._elementStyle;
+
+  let idRule = elementStyle.rules[1];
+  let idProp = idRule.textProps[0];
+  ok(idProp.overridden, "Not-important rule should be overridden.");
+
+  let classRule = elementStyle.rules[2];
+  let classProp = classRule.textProps[0];
+  ok(!classProp.overridden, "Important rule should not be overridden.");
+
+  styleNode.remove();
+
+  let elementRule = elementStyle.rules[0];
+  let elementProp = elementRule.createProperty("background-color", "purple", "important");
+  yield elementRule._applyingModifications;
+
+  ok(classProp.overridden, "New important prop should override class property.");
+  ok(!elementProp.overridden, "New important prop should not be overriden.");
+}
+
+function* disableOverride(inspector, view) {
+  let styleNode = yield createTestContent(inspector, '' +
+    '#testid {' +
+    '  background-color: blue;' +
+    '}' +
+    '.testclass {' +
+    '  background-color: green;' +
+    '}');
+
+  let elementStyle = view._elementStyle;
+
+  let idRule = elementStyle.rules[1];
+  let idProp = idRule.textProps[0];
+
+  idProp.setEnabled(false);
+  yield idRule._applyingModifications;
+
+  let classRule = elementStyle.rules[2];
+  let classProp = classRule.textProps[0];
+  ok(!classProp.overridden, "Class prop should not be overridden after id prop was disabled.");
+
+  styleNode.remove();
+  yield inspector.once("inspector-updated");
+}