Async-step, first cut.

runtime/observatory/tests/service/async_continuation_test.dart

+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// VMOptions=--compile_all --error_on_bad_type --error_on_bad_override --verbose-debug
+
+import 'dart:async';
+import 'dart:developer';
+import 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+import 'test_helper.dart';
+
+foo() {}
+
+doSync() {
+  foo();  // Line 15
+}
+
+doAsync() async {
+  foo();  // Line 19
+  await null;
+}
+
+doAsyncStar() async* {
+  foo();  // Line 24
+  yield null;
+}
+
+testeeDo() {
+  debugger();
+
+  doSync();
+
+  doAsync();
+
+  doAsyncStar().listen((_) => null);
+}
+
+test(Isolate isolate) async {
+  await isolate.rootLibrary.load();
+  var script = isolate.rootLibrary.scripts[0];
+
+  var bp1 = await isolate.addBreakpoint(script, 15);
+  expect(bp1, isNotNull);
+  expect(bp1 is Breakpoint, isTrue);
+
+  var bp2 = await isolate.addBreakpoint(script, 19);
+  expect(bp2, isNotNull);
+  expect(bp2 is Breakpoint, isTrue);
+
+  var bp3 = await isolate.addBreakpoint(script, 24);
+  expect(bp3, isNotNull);
+  expect(bp3 is Breakpoint, isTrue);
+
+  isolate.resume();
+
+  var bp1_hit = new Completer();
+  var bp2_hit = new Completer();
+  var bp3_hit = new Completer();
+
+  var stream = await isolate.vm.getEventStream(VM.kDebugStream);
+  stream.listen((ServiceEvent event) async {
+    print("Event: $event");
+    if (event.kind == ServiceEvent.kPauseBreakpoint) {
+      var bp = event.breakpoint;
+      print('Hit $bp');
+      if (bp == bp1) {
+        await stoppedAtLine(15)(isolate);
+        print(event.asyncContinuation);
+        expect(event.asyncContinuation.isNull, isTrue);
+        isolate.resume();
+        bp1_hit.complete(null);
+      }
+      if (bp == bp2) {
+        await stoppedAtLine(19)(isolate);
+        print(event.asyncContinuation);
+        expect(event.asyncContinuation.isClosure, isTrue);
+        isolate.resume();
+        bp2_hit.complete(null);
+      }
+      if (bp == bp3) {
+        await stoppedAtLine(24)(isolate);
+        print(event.asyncContinuation);
+        expect(event.asyncContinuation.isClosure, isTrue);
+        isolate.resume();
+        bp3_hit.complete(null);
+      }
+    }
+  });
+
+  await bp1_hit.future;
+  await bp2_hit.future;
+  await bp3_hit.future;
+}
+
+main(args) => runIsolateTests(args, [test], testeeConcurrent: testeeDo);