diff -r 000000000000 -r 6474c204b198 browser/devtools/debugger/test/browser_dbg_pause-resume.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/debugger/test/browser_dbg_pause-resume.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,78 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests if pausing and resuming in the main loop works properly.
+ */
+
+const TAB_URL = EXAMPLE_URL + "doc_pause-exceptions.html";
+
+let gTab, gDebuggee, gPanel, gDebugger;
+let gResumeButton, gResumeKey, gFrames;
+
+function test() {
+  initDebugger(TAB_URL).then(([aTab, aDebuggee, aPanel]) => {
+    gTab = aTab;
+    gDebuggee = aDebuggee;
+    gPanel = aPanel;
+    gDebugger = gPanel.panelWin;
+    gResumeButton = gDebugger.document.getElementById("resume");
+    gResumeKey = gDebugger.document.getElementById("resumeKey");
+    gFrames = gDebugger.DebuggerView.StackFrames;
+
+    testPause();
+  });
+}
+
+function testPause() {
+  is(gDebugger.gThreadClient.paused, false,
+    "Should be running after starting the test.");
+
+  is(gResumeButton.getAttribute("tooltiptext"),
+     gDebugger.L10N.getFormatStr("pauseButtonTooltip",
+      gDebugger.ShortcutUtils.prettifyShortcut(gResumeKey)),
+    "Button tooltip should be 'pause' when running.");
+
+  gDebugger.gThreadClient.addOneTimeListener("paused", () => {
+    is(gDebugger.gThreadClient.paused, true,
+      "Should be paused after an interrupt request.");
+
+    is(gResumeButton.getAttribute("tooltiptext"),
+       gDebugger.L10N.getFormatStr("resumeButtonTooltip",
+        gDebugger.ShortcutUtils.prettifyShortcut(gResumeKey)),
+      "Button tooltip should be 'resume' when paused.");
+
+    is(gFrames.itemCount, 0,
+      "Should have no frames when paused in the main loop.");
+
+    testResume();
+  });
+
+  EventUtils.sendMouseEvent({ type: "mousedown" }, gResumeButton, gDebugger);
+}
+
+function testResume() {
+  gDebugger.gThreadClient.addOneTimeListener("resumed", () => {
+    is(gDebugger.gThreadClient.paused, false,
+      "Should be paused after an interrupt request.");
+
+    is(gResumeButton.getAttribute("tooltiptext"),
+       gDebugger.L10N.getFormatStr("pauseButtonTooltip",
+        gDebugger.ShortcutUtils.prettifyShortcut(gResumeKey)),
+      "Button tooltip should be pause when running.");
+
+    closeDebuggerAndFinish(gPanel);
+  });
+
+  EventUtils.sendMouseEvent({ type: "mousedown" }, gResumeButton, gDebugger);
+}
+
+registerCleanupFunction(function() {
+  gTab = null;
+  gDebuggee = null;
+  gPanel = null;
+  gDebugger = null;
+  gResumeButton = null;
+  gResumeKey = null;
+  gFrames = null;
+});