Add an option to run skipped tests.

test/runner/json_reporter_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:convert';
 
 import 'package:path/path.dart' as p;
 import 'package:scheduled_test/descriptor.dart' as d;
@@ skipping 347 matching lines @@
           test('success 1', () {});
           test('success 2', () {});
           test('success 3', () {});
         }, skip: true);
       """, [
         _start,
         _allSuites(),
         _suite(0),
         _testStart(1, "loading test.dart", groupIDs: []),
         _testDone(1, hidden: true),
-        _group(2, testCount: 0),
-        _group(3, name: "skip", parentID: 2, skip: true, testCount: 0,
+        _group(2, testCount: 3),
+        _group(3, name: "skip", parentID: 2, skip: true, testCount: 3,
             line: 6, column: 9),
-        _testStart(4, "skip", groupIDs: [2, 3], skip: true,
-            line: 6, column: 9),
+        _testStart(4, "skip success 1", groupIDs: [2, 3], skip: true,
+            line: 7, column: 11),
         _testDone(4, skipped: true),
+        _testStart(5, "skip success 2", groupIDs: [2, 3], skip: true,
+            line: 8, column: 11),
+        _testDone(5, skipped: true),
+        _testStart(6, "skip success 3", groupIDs: [2, 3], skip: true,
+            line: 9, column: 11),
+        _testDone(6, skipped: true),
         _done()
       ]);
     });
 
     test("reports the skip reason if available", () {
       _expectReport("""
         test('skip 1', () {}, skip: 'some reason');
         test('skip 2', () {}, skip: 'or another');
       """, [
         _start,
          _allSuites(),
         _suite(0),
         _testStart(1, "loading test.dart", groupIDs: []),
         _testDone(1, hidden: true),
         _group(2, testCount: 2),
         _testStart(3, "skip 1", skip: "some reason", line: 6, column: 9),
         _print(3, "Skip: some reason", type: "skip"),
         _testDone(3, skipped: true),
         _testStart(4, "skip 2", skip: "or another", line: 7, column: 9),
         _print(4, "Skip: or another", type: "skip"),
         _testDone(4, skipped: true),
         _done()
       ]);
     });
+
+    test("runs skipped tests with --run-skipped", () {
+      _expectReport("""
+        test('skip 1', () {}, skip: 'some reason');
+        test('skip 2', () {}, skip: 'or another');
+      """, [
+        _start,
+         _allSuites(),
+        _suite(0),
+        _testStart(1, "loading test.dart", groupIDs: []),
+        _testDone(1, hidden: true),
+        _group(2, testCount: 2),
+        _testStart(3, "skip 1", line: 6, column: 9),
+        _testDone(3),
+        _testStart(4, "skip 2", line: 7, column: 9),
+        _testDone(4),
+        _done()
+      ], args: ["--run-skipped"]);
+    });
   });
 
   group("reports line and column numbers for", () {
     test("the first call to setUpAll()", () {
       _expectReport("""
         setUpAll(() {});
         setUpAll(() {});
         setUpAll(() {});
         test('success', () {});
       """, [
@@ skipping 247 matching lines @@
 /// Returns the serialized metadata corresponding to [skip].
 Map _metadata({skip}) {
   if (skip == true) {
     return {"skip": true, "skipReason": null};
   } else if (skip is String) {
     return {"skip": true, "skipReason": skip};
   } else {
     return {"skip": false, "skipReason": null};
   }
 }