Add support for configuration presets.

lib/src/executable.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.
 
 // TODO(nweiz): This is under lib so that it can be used by the unittest dummy
 // package. Once that package is no longer being updated, move this back into
 // bin.
 import 'dart:io';
 
 import 'package:source_span/source_span.dart';
@@ skipping 86 matching lines @@
   } on FormatException catch (error) {
     stderr.writeln(error.message);
     exitCode = exit_codes.data;
     return;
   } on IOException catch (error) {
     stderr.writeln(error.toString());
     exitCode = exit_codes.noInput;
     return;
   }
 
+  var undefinedPresets =
+      configuration.chosenPresets
+          .where((preset) => !configuration.knownPresets.contains(preset))
+          .toList();
+  if (undefinedPresets.isNotEmpty) {
+    _printUsage("Undefined ${pluralize('preset', undefinedPresets.length)} "
+        "${toSentence(undefinedPresets.map((preset) => '"$preset"'))}.");
+    exitCode = exit_codes.usage;
+    return;
+  }
+
   if (configuration.pubServeUrl != null && !_usesTransformer) {
     stderr.write('''
 When using --pub-serve, you must include the "test/pub_serve" transformer in
 your pubspec:
 
 transformers:
 - test/pub_serve:
     \$include: test/**_test.dart
 ''');
     exitCode = exit_codes.data;
@@ skipping 45 matching lines @@
 /// thing is printed to stderr instead of stdout.
 void _printUsage([String error]) {
   var output = stdout;
 
   var message = "Runs tests in this package.";
   if (error != null) {
     message = error;
     output = stderr;
   }
 
-  output.write("""$message
+  output.write("""${wordWrap(message)}
 
 Usage: pub run test:test [files or directories...]
 
 ${Configuration.usage}
 """);
 }