diff -r 000000000000 -r 6474c204b198 browser/devtools/debugger/test/browser_dbg_tracing-05.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/devtools/debugger/test/browser_dbg_tracing-05.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,85 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Test that text describing the tracing state is correctly displayed.
+ */
+
+const TAB_URL = EXAMPLE_URL + "doc_tracing-01.html";
+
+let gTab, gDebuggee, gPanel, gDebugger;
+let gTracer, gL10N;
+
+function test() {
+  SpecialPowers.pushPrefEnv({'set': [["devtools.debugger.tracer", true]]}, () => {
+    initDebugger(TAB_URL).then(([aTab, aDebuggee, aPanel]) => {
+      gTab = aTab;
+      gDebuggee = aDebuggee;
+      gPanel = aPanel;
+      gDebugger = gPanel.panelWin;
+      gTracer = gDebugger.DebuggerView.Tracer;
+      gL10N = gDebugger.L10N;
+
+      waitForSourceShown(gPanel, "code_tracing-01.js")
+        .then(testTracingNotStartedText)
+        .then(() => gTracer._onStartTracing())
+        .then(testFunctionCallsUnavailableText)
+        .then(clickButton)
+        .then(() => waitForClientEvents(aPanel, "traces"))
+        .then(testNoEmptyText)
+        .then(() => gTracer._onClear())
+        .then(testFunctionCallsUnavailableText)
+        .then(() => gTracer._onStopTracing())
+        .then(testTracingNotStartedText)
+        .then(() => gTracer._onClear())
+        .then(testTracingNotStartedText)
+        .then(() => {
+          const deferred = promise.defer();
+          SpecialPowers.popPrefEnv(deferred.resolve);
+          return deferred.promise;
+        })
+        .then(() => closeDebuggerAndFinish(gPanel))
+        .then(null, aError => {
+          DevToolsUtils.reportException("browser_dbg_tracing-05.js", aError);
+          ok(false, "Got an error: " + aError.message + "\n" + aError.stack);
+        });
+    });
+  });
+}
+
+function testTracingNotStartedText() {
+  let label = gDebugger.document.querySelector("#tracer-tabpanel .fast-list-widget-empty-text");
+  ok(label,
+    "A label is displayed in the tracer tabpanel.");
+  is(label.getAttribute("value"), gL10N.getStr("tracingNotStartedText"),
+    "The correct {{tracingNotStartedText}} is displayed in the tracer tabpanel.");
+}
+
+function testFunctionCallsUnavailableText() {
+  let label = gDebugger.document.querySelector("#tracer-tabpanel .fast-list-widget-empty-text");
+  ok(label,
+    "A label is displayed in the tracer tabpanel.");
+  is(label.getAttribute("value"), gL10N.getStr("noFunctionCallsText"),
+    "The correct {{noFunctionCallsText}} is displayed in the tracer tabpanel.");
+}
+
+function testNoEmptyText() {
+  let label = gDebugger.document.querySelector("#tracer-tabpanel .fast-list-widget-empty-text");
+  ok(!label,
+    "No label should be displayed in the tracer tabpanel.");
+}
+
+function clickButton() {
+  EventUtils.sendMouseEvent({ type: "click" },
+                            gDebuggee.document.querySelector("button"),
+                            gDebuggee);
+}
+
+registerCleanupFunction(function() {
+  gTab = null;
+  gDebuggee = null;
+  gPanel = null;
+  gDebugger = null;
+  gTracer = null;
+  gL10N = null;
+});