diff -r 000000000000 -r 6474c204b198 browser/devtools/styleinspector/test/browser_computedview_no-results-placeholder.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/styleinspector/test/browser_computedview_no-results-placeholder.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,73 @@
+/* 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";
+
+// Tests that the no results placeholder works properly.
+
+let test = asyncTest(function*() {
+  yield addTab("data:text/html,no results placeholder test");
+
+  info("Creating the test document");
+  content.document.body.innerHTML = '<style type="text/css"> ' +
+    '.matches {color: #F00;}</style>' +
+    '<span id="matches" class="matches">Some styled text</span>';
+  content.document.title = "Tests that the no results placeholder works properly";
+
+  info("Opening the computed view");
+  let {toolbox, inspector, view} = yield openComputedView();
+
+  info("Selecting the test node");
+  yield selectNode("#matches", inspector);
+
+  yield enterInvalidFilter(inspector, view);
+  checkNoResultsPlaceholderShown(view);
+
+  yield clearFilterText(inspector, view);
+  checkNoResultsPlaceholderHidden(view);
+});
+
+function* enterInvalidFilter(inspector, computedView) {
+  let searchbar = computedView.searchField;
+  let searchTerm = "xxxxx";
+
+  info("setting filter text to \"" + searchTerm + "\"");
+
+  let onRefreshed = inspector.once("computed-view-refreshed");
+  searchbar.focus();
+  for each (let c in searchTerm) {
+    EventUtils.synthesizeKey(c, {}, computedView.styleWindow);
+  }
+  yield onRefreshed;
+}
+
+function checkNoResultsPlaceholderShown(computedView) {
+  info("Checking that the no results placeholder is shown");
+
+  let placeholder = computedView.noResults;
+  let win = computedView.styleWindow;
+  let display = win.getComputedStyle(placeholder).display;
+  is(display, "block", "placeholder is visible");
+}
+
+function* clearFilterText(inspector, computedView) {
+  info("Clearing the filter text");
+
+  let searchbar = computedView.searchField;
+
+  let onRefreshed = inspector.once("computed-view-refreshed");
+  searchbar.focus();
+  searchbar.value = "";
+  EventUtils.synthesizeKey("c", {}, computedView.styleWindow);
+  yield onRefreshed;
+}
+
+function checkNoResultsPlaceholderHidden(computedView) {
+  info("Checking that the no results placeholder is hidden");
+
+  let placeholder = computedView.noResults;
+  let win = computedView.styleWindow;
+  let display = win.getComputedStyle(placeholder).display;
+  is(display, "none", "placeholder is hidden");
+}