Trigger debug event on not yet caught exception in promises.

test/mjsunit/es6/debug-promises-caught.js

+// Copyright 2014 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --harmony-promises --expose-debug-as debug
+
+Debug = debug.Debug;
+
+var resolve_fun;
+var log = [];
+
+var p = new Promise(function(resolve, reject) {
+  log.push("resolve");
+  resolve();
+});
+
+var q = p.chain(
+  function() {
+    log.push("throw");
+    throw new Error("caught");
+  });
+
+q.catch(function(e) {
+  assertEquals("caught", e.message);
+});
+
+function listener(event, exec_state, event_data, data) {
+  try {
+    assertEquals(["resolve", "end main", "throw"], log);

[yurys, 2014/04/24 07:48:43]

Just curious: I'd expect "end main" to be logged before "resolve" or does
Promise evaluate synchronously in this case?

[Yang, 2014/04/24 07:59:59]

Yes. The function in line 12 is executed immediately. However, the chained
function in line 18 is put into the micro task queue and executed after this
test script is finished executing.

+    assertTrue(event != Debug.DebugEvent.PendingExceptionInPromise);
+    if (event == Debug.DebugEvent.Exception) {
+      assertEquals("caught", event_data.exception().message);
+      assertEquals(undefined, event_data.deferred_promise());
+    }
+  } catch (e) {
+    // Signal a failure with exit code 1.  This is necessary since the
+    // debugger swallows exceptions and we expect the chained function
+    // and this listener to be executed after the main script is finished.
+    print(e + "\n" + e.stack);

[rossberg, 2014/04/24 07:27:36]

Maybe add "Unexpected exception: ".

+    quit(1);
+  }
+}
+
+Debug.setBreakOnException();
+Debug.setListener(listener);
+
+log.push("end main");