Add general method for comma separated options.

pkg/testing/lib/src/run_tests.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.md file.
 
 library testing.run_tests;
 
 import 'dart:async' show
     Future;
 
 import 'dart:io' show
@@ skipping 31 matching lines @@
     Suite;
 
 class CommandLine {
   final Set<String> options;
   final List<String> arguments;
 
   CommandLine(this.options, this.arguments);
 
   bool get verbose => options.contains("--verbose") || options.contains("-v");
 
-  Set<String> get skip {
+  Set<String> get skip => commaSeparated("--skip=");
+
+  Set<String> commaSeparated(String prefix) {
     return options.expand((String s) {
-      const String prefix = "--skip=";
       if (!s.startsWith(prefix)) return const [];
       s = s.substring(prefix.length);
       return s.split(",");
     }).toSet();
   }
 
   Map<String, String> get environment {
     Map<String, String> result = <String, String>{};
     for (String option in options) {
       if (option.startsWith("-D")) {
@@ skipping 131 matching lines @@
       }, printLineOnStdout: sb.writeln);
       logMessage(sb);
     } catch (e) {
       print(sb);
       rethrow;
     }
     logTestComplete(++completed, 0, tests.length, null, null);
   }
   logSuiteComplete();
 });