diff -r 000000000000 -r 6474c204b198 toolkit/devtools/server/tests/unit/test_trace_actor-07.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/devtools/server/tests/unit/test_trace_actor-07.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,100 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests that the exit frame packets get the correct `why` value.
+ */
+
+var gDebuggee;
+var gClient;
+var gTraceClient;
+
+function run_test()
+{
+  initTestTracerServer();
+  gDebuggee = addTestGlobal("test-tracer-actor");
+  gClient = new DebuggerClient(DebuggerServer.connectPipe());
+  gClient.connect(function() {
+    attachTestTab(gClient, "test-tracer-actor", function(aResponse, aTabClient) {
+      gClient.attachTracer(aResponse.traceActor, function(aResponse, aTraceClient) {
+        gTraceClient = aTraceClient;
+        test_exit_frame_whys();
+      });
+    });
+  });
+  do_test_pending();
+}
+
+function test_exit_frame_whys()
+{
+  gClient.addListener("traces", (aEvent, { traces }) => {
+    for (let t of traces) {
+      if (t.type == "exitedFrame") {
+        check_trace(t);
+      }
+    }
+  });
+
+  start_trace()
+    .then(eval_code)
+    .then(stop_trace)
+    .then(function() {
+      finishClient(gClient);
+    }).then(null, error => {
+      do_check_true(false, "Should not get an error, got: " + error);
+    });
+}
+
+function start_trace()
+{
+  let deferred = promise.defer();
+  gTraceClient.startTrace(["name"], null, function() { deferred.resolve(); });
+  return deferred.promise;
+}
+
+function eval_code()
+{
+  gDebuggee.eval("(" + function() {
+    function thrower() {
+      throw new Error();
+    }
+
+    function* yielder() {
+      yield 1;
+    }
+
+    function returner() {
+      return 1;
+    }
+
+    try {
+      thrower();
+    } catch(e) {}
+
+    // XXX bug 923729: Can't test yielding yet.
+    // for (let x of yielder()) {
+    //   break;
+    // }
+
+    returner();
+  } + ")()");
+}
+
+function stop_trace()
+{
+  let deferred = promise.defer();
+  gTraceClient.stopTrace(null, function() { deferred.resolve(); });
+  return deferred.promise;
+}
+
+function check_trace(aEvent, { sequence, why })
+{
+  switch(sequence) {
+  case 3:
+    do_check_eq(why, "throw");
+    break;
+  case 5:
+    do_check_eq(why, "return");
+    break;
+  }
+}