Add support for a timeout flag.

test/runner/timeout_test.dart

+// Copyright (c) 2016, 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.
+
+@TestOn("vm")
+
+import 'dart:io';
+import 'dart:math' as math;
+
+import 'package:scheduled_test/descriptor.dart' as d;
+import 'package:scheduled_test/scheduled_stream.dart';
+import 'package:scheduled_test/scheduled_test.dart';
+import 'package:test/src/util/exit_codes.dart' as exit_codes;
+
+import '../io.dart';
+
+void main() {
+  useSandbox();
+
+  test("respects top-level @Timeout declarations", () {
+    d.file("test.dart", '''
+@Timeout(const Duration(seconds: 0))
+
+import 'dart:async';
+
+import 'package:test/test.dart';
+
+void main() {
+  test("timeout", () async {
+    await new Future.delayed(Duration.ZERO);
+  });
+}
+''').create();
+
+    var test = runTest(["test.dart"]);
+    test.stdout.expect(containsInOrder([
+      "Test timed out after 0 seconds.",
+      "-1: Some tests failed."
+    ]));
+    test.shouldExit(1);
+  });
+
+  test("respects the --timeout flag", () {
+    d.file("test.dart", '''
+import 'dart:async';
+
+import 'package:test/test.dart';
+
+void main() {
+  test("timeout", () async {
+    await new Future.delayed(Duration.ZERO);
+  });
+}
+''').create();
+
+    var test = runTest(["--timeout=0s", "test.dart"]);
+    test.stdout.expect(containsInOrder([
+      "Test timed out after 0 seconds.",
+      "-1: Some tests failed."
+    ]));
+    test.shouldExit(1);
+  });
+
+  test("the --timeout flag applies on top of the default 30s timeout", () {
+    d.file("test.dart", '''
+import 'dart:async';
+
+import 'package:test/test.dart';
+
+void main() {
+  test("no timeout", () async {
+    await new Future.delayed(new Duration(milliseconds: 250));
+  });
+
+  test("timeout", () async {
+    await new Future.delayed(new Duration(milliseconds: 750));
+  });
+}
+''').create();
+
+    // This should make the timeout about 500ms, which should cause exactly one
+    // test to fail.
+    var test = runTest(["--timeout=0.016x", "test.dart"]);
+    test.stdout.expect(containsInOrder([
+      "Test timed out after 0.4 seconds.",
+      "-1: Some tests failed."
+    ]));
+    test.shouldExit(1);
+  });
+}
+