Add an option to run skipped tests.

test/runner/runner_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.
 
 @TestOn("vm")
 
 import 'dart:io';
 import 'dart:math' as math;
 
 import 'package:scheduled_test/descriptor.dart' as d;
@@ skipping 43 matching lines @@
 
 -N, --plain-name               A plain-text substring of the name of the test to run.
                                If passed multiple times, tests must match all substrings.
 
 -t, --tags                     Run only tests with all of the specified tags.
                                Supports boolean selector syntax.
 
 -x, --exclude-tags             Don't run tests with any of the specified tags.
                                Supports boolean selector syntax.
 
+    --[no-]run-skipped         Run skipped tests instead of skipping them.
+
 ======== Running Tests
 -p, --platform                 The platform(s) on which to run the tests.
                                $_browsers
 
 -P, --preset                   The configuration preset(s) to use.
 -j, --concurrency=<threads>    The number of concurrent test suites run.
                                (defaults to "$_defaultConcurrency")
 
     --pub-serve=<port>         The port of a pub serve instance serving "test/".
     --timeout                  The default test timeout. For example: 15s, 2x, none
@@ skipping 278 matching lines @@
   });
 
   test("runs tests even when a file fails to load", () {
     d.file("test.dart", _success).create();
 
     var test = runTest(["test.dart", "nonexistent.dart"]);
     test.stdout.expect(consumeThrough(contains("+1 -1: Some tests failed.")));
     test.shouldExit(1);
   });
 
-  test("respects top-level @Skip declarations", () {
-    d.file("test.dart", '''
-@Skip()
+  group("with a top-level @Skip declaration", () {
+    setUp(() {
+      d.file("test.dart", '''
+        @Skip()
 
-import 'dart:async';
+        import 'dart:async';
 
-import 'package:test/test.dart';
+        import 'package:test/test.dart';
 
-void main() {
-  test("fail", () => throw 'oh no');
-}
-''').create();
+        void main() {
+          test("success", () {});
+        }
+      ''').create();
+    });
 
-    var test = runTest(["test.dart"]);
-    test.stdout.expect(consumeThrough(contains("+0 ~1: All tests skipped.")));
-    test.shouldExit(0);
+    test("skips all tests", () {
+      var test = runTest(["test.dart"]);
+      test.stdout.expect(consumeThrough(contains("+0 ~1: All tests skipped.")));
+      test.shouldExit(0);
+    });
+
+    test("runs all tests with --run-skipped", () {
+      var test = runTest(["--run-skipped", "test.dart"]);
+      test.stdout.expect(consumeThrough(contains("+1: All tests passed!")));
+      test.shouldExit(0);
+    });
   });
 
   group("with onPlatform", () {
     test("respects matching Skips", () {
       d.file("test.dart", '''
 import 'dart:async';
 
 import 'package:test/test.dart';
 
 void main() {
@@ skipping 176 matching lines @@
   });
 
   test("with the --color flag, uses colors", () {
     d.file("test.dart", _failure).create();
     var test = runTest(["--color", "test.dart"]);
     // This is the color code for red.
     test.stdout.expect(consumeThrough(contains("\u001b[31m")));
     test.shouldExit();
   });
 }