Support --special-command test option. As a special case support --valgrind option.

tools/testing/dart/test_options.dart

Index: tools/testing/dart/test_options.dart
diff --git a/tools/testing/dart/test_options.dart b/tools/testing/dart/test_options.dart
index 2d398f2ab4034332e4159cae2986e5ee3f75b749..36b8c870fe672c5fd3f0b31e171be168fcbbd50d 100644
--- a/tools/testing/dart/test_options.dart
+++ b/tools/testing/dart/test_options.dart
@@ -34,6 +34,18 @@ class _TestOptionSpecification {
  * Parser of test options.
  */
 class TestOptionsParser {
+  String specialCommandHelp =
+"""
+Special command support. Wraps the command line in
+a special command. The special command should contain
+an '@' character which will be replaced by the normal
+command.
+
+For example if the normal command that will be executed
+is 'dart file.dart' and you specify special command
+'python -u valgrind.py @ suffix' the final command will be
+'python -u valgrind.py dart file.dart suffix'""";
+
   /**
    * Creates a test options parser initialized with the known options.
    */
@@ -85,7 +97,7 @@ class TestOptionsParser {
               'compact'),
           new _TestOptionSpecification(
               'report',
-              'Print a summary report of the number of tests, by expectation.',
+              'Print a summary report of the number of tests, by expectation',
               ['--report'],
               [],
               false,
@@ -110,7 +122,20 @@ class TestOptionsParser {
               ['-v', '--verbose'],
               [],
               false,
-              'bool')];
+              'bool'),
+          new _TestOptionSpecification(
+              'valgrind',
+              'Run tests through valgrind',
+              ['--valgrind'],
+              [],
+              false,
+              'bool'),
+          new _TestOptionSpecification(
+              'special-command',
+              specialCommandHelp,
+              ['--special-command'],
+              [],
+              '')];
   }
 
 
@@ -236,6 +261,16 @@ class TestOptionsParser {
     if (configuration['component'] == 'most') {
       configuration['component'] = 'vm,dartc';
     }
+    if (configuration['valgrind']) {
+      // TODO(ager): Get rid of this when there is only one checkout and
+      // we don't have to special case for the runtime checkout.
+      File valgrindFile = new File('runtime/tools/valgrind.py');
+      if (!valgrindFile.existsSync()) {
+        valgrindFile = new File('../runtime/tools/valgrind.py');
+      }
+      String valgrind = valgrindFile.fullPathSync();
+      configuration['special-command'] = 'python -u $valgrind @';
+    }
 
     // Use verbose progress indication for verbose output.
     if (configuration['verbose']) {