Async-step, first cut.

runtime/observatory/tests/service/async_step_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 'package:observatory/service_io.dart';
+import 'package:unittest/unittest.dart';
+import 'test_helper.dart';
+import 'dart:developer';
+
+foo() async { }
+
+doAsync(stop) async {
+  if (stop) debugger();
+  await foo(); // Line 15.
+  await foo(); // Line 16.
+  await foo(); // Line 17.
+  return null;
+}
+
+testMain() {
+  // With two runs of doAsync floating around, async step should only cause
+  // us to stop in the run we started in.
+  doAsync(false);
+  doAsync(true);
+}
+
+
+asyncStep(Isolate isolate) async {
+  var event = isolate.pauseEvent;
+  expect(event, isNotNull);
+
+  // 1. Set breakpoint for the continuation and resume the isolate.
+  Instance continuation = event.asyncContinuation;
+  print("Async continuation is $continuation");
+  expect(continuation.isClosure, isTrue);
+
+  var bpt = await isolate.addBreakOnActivation(continuation);
+  expect(bpt is Breakpoint, isTrue);
+  print("Async step to $bpt");
+
+  print("A");
+  await isolate.resume();
+  print("AA");
+  await hasStoppedAtBreakpoint(isolate);
+
+  // 2. Step past the state-machine dispatch.
+  print("AAA");
+  await isolate.stepOver();
+  print("AAAA");
+  await hasStoppedAtBreakpoint(isolate);
+}
+
+// Currying is your friend.
+atLine(int line) {

[Cutch, 2015/07/15 17:04:23]

Add a return type 'IsolateTest':

IsolateTest atLine(int line) ...

Move this to test_helper.dart

[rmacnak, 2015/07/16 19:42:17]

Done.

+  return (Isolate isolate) async {
+    ServiceMap stack = await isolate.getStack();
+    expect(stack.type, equals('Stack'));
+    expect(stack['frames'].length, greaterThanOrEqualTo(1));
+
+    Script script = stack['frames'][0].location.script;
+    await script.load();
+    expect(script.tokenToLine(stack['frames'][0].location.tokenPos),
+           equals(line));
+  };
+}
+
+
+var tests = [
+  hasStoppedAtBreakpoint,
+  atLine(15),
+  asyncStep,
+  atLine(16),
+  asyncStep,
+  atLine(17),
+  resumeIsolate,
+];
+
+main(args) => runIsolateTests(args, tests, testeeConcurrent: testMain);