diff -r 000000000000 -r 6474c204b198 browser/devtools/debugger/test/browser_dbg_variables-view-popup-12.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/debugger/test/browser_dbg_variables-view-popup-12.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,71 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests that the clicking "Watch" button twice, for the same expression, only adds it
+ * once.
+ */
+
+const TAB_URL = EXAMPLE_URL + "doc_watch-expression-button.html";
+
+function test() {
+  Task.spawn(function() {
+    let [tab, debuggee, panel] = yield initDebugger(TAB_URL);
+    let win = panel.panelWin;
+    let events = win.EVENTS;
+    let watch = win.DebuggerView.WatchExpressions;
+    let bubble = win.DebuggerView.VariableBubble;
+    let tooltip = bubble._tooltip.panel;
+
+    function verifyContent(aExpression, aItemCount) {
+
+      ok(watch.getItemAtIndex(0),
+        "The expression at index 0 should be available.");
+      is(watch.getItemAtIndex(0).attachment.initialExpression, aExpression,
+        "The expression at index 0 is correct.");
+      is(watch.itemCount, aItemCount,
+        "The expression count is correct.");
+    }
+
+    // Allow this generator function to yield first.
+    executeSoon(() => debuggee.start());
+    yield waitForSourceAndCaretAndScopes(panel, ".html", 19);
+
+    // Inspect primitive value variable.
+    yield openVarPopup(panel, { line: 15, ch: 12 });
+    let popupHiding = once(tooltip, "popuphiding");
+    let expressionsEvaluated = waitForDebuggerEvents(panel, events.FETCHED_WATCH_EXPRESSIONS);
+    tooltip.querySelector("button").click();
+    verifyContent("a", 1);
+    yield promise.all([popupHiding, expressionsEvaluated]);
+    ok(true, "The new watch expressions were re-evaluated and the panel got hidden (1).");
+
+    // Inspect property of an object.
+    let expressionsEvaluated = waitForDebuggerEvents(panel, events.FETCHED_WATCH_EXPRESSIONS);
+    yield openVarPopup(panel, { line: 17, ch: 10 });
+    yield expressionsEvaluated;
+    ok(true, "The watch expressions were re-evaluated when a new panel opened (1).");
+
+    let popupHiding = once(tooltip, "popuphiding");
+    let expressionsEvaluated = waitForDebuggerEvents(panel, events.FETCHED_WATCH_EXPRESSIONS);
+    tooltip.querySelector("button").click();
+    verifyContent("b.a", 2);
+    yield promise.all([popupHiding, expressionsEvaluated]);
+    ok(true, "The new watch expressions were re-evaluated and the panel got hidden (2).");
+
+    // Re-inspect primitive value variable.
+    let expressionsEvaluated = waitForDebuggerEvents(panel, events.FETCHED_WATCH_EXPRESSIONS);
+    yield openVarPopup(panel, { line: 15, ch: 12 });
+    yield expressionsEvaluated;
+    ok(true, "The watch expressions were re-evaluated when a new panel opened (2).");
+
+    let popupHiding = once(tooltip, "popuphiding");
+    let expressionsEvaluated = waitForDebuggerEvents(panel, events.FETCHED_WATCH_EXPRESSIONS);
+    tooltip.querySelector("button").click();
+    verifyContent("b.a", 2);
+    yield promise.all([popupHiding, expressionsEvaluated]);
+    ok(true, "The new watch expressions were re-evaluated and the panel got hidden (3).");
+
+    yield resumeDebuggerThenCloseAndFinish(panel);
+  });
+}