diff -r 000000000000 -r 6474c204b198 browser/devtools/styleinspector/test/unit/test_parseSingleValue.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/styleinspector/test/unit/test_parseSingleValue.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,76 @@
+/* -*- Mode: Javascript; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=2 et sw=2 tw=80: */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const Cu = Components.utils;
+Cu.import("resource://gre/modules/devtools/Loader.jsm");
+const {parseSingleValue} = devtools.require("devtools/styleinspector/css-parsing-utils");
+
+const TEST_DATA = [
+  {input: null, throws: true},
+  {input: undefined, throws: true},
+  {input: "", expected: {value: "", priority: ""}},
+  {input: "  \t \t \n\n  ", expected: {value: "", priority: ""}},
+  {input: "blue", expected: {value: "blue", priority: ""}},
+  {input: "blue !important", expected: {value: "blue", priority: "important"}},
+  {input: "blue!important", expected: {value: "blue", priority: "important"}},
+  {input: "blue ! important", expected: {value: "blue", priority: "important"}},
+  {input: "blue !  important", expected: {value: "blue", priority: "important"}},
+  {input: "blue !", expected: {value: "blue", priority: ""}},
+  {input: "blue !mportant", expected: {value: "blue !mportant", priority: ""}},
+  {input: "  blue   !important ", expected: {value: "blue", priority: "important"}},
+  {
+    input: "url(\"http://url.com/whyWouldYouDoThat!important.png\") !important",
+    expected: {
+      value: "url(\"http://url.com/whyWouldYouDoThat!important.png\")",
+      priority: "important"
+    }
+  },
+  {
+    input: "url(\"http://url.com/whyWouldYouDoThat!important.png\")",
+    expected: {
+      value: "url(\"http://url.com/whyWouldYouDoThat!important.png\")",
+      priority: ""
+    }
+  },
+  {
+    input: "\"content!important\" !important",
+    expected: {
+      value: "\"content!important\"",
+      priority: "important"
+    }
+  },
+  {
+    input: "\"content!important\"",
+    expected: {
+      value: "\"content!important\"",
+      priority: ""
+    }
+  }
+];
+
+function run_test() {
+  for (let test of TEST_DATA) {
+    do_print("Test input value " + test.input);
+    try {
+      let output = parseSingleValue(test.input);
+      assertOutput(output, test.expected);
+    } catch (e) {
+      do_print("parseSingleValue threw an exception with the given input value");
+      if (test.throws) {
+        do_print("Exception expected");
+        do_check_true(true);
+      } else {
+        do_print("Exception unexpected\n" + e);
+        do_check_true(false);
+      }
+    }
+  }
+}
+
+function assertOutput(actual, expected) {
+  do_print("Check that the output has the expected value and priority");
+  do_check_eq(expected.value, actual.value);
+  do_check_eq(expected.priority, actual.priority);
+}