Allow testing script to run without the package directories being present

tools/testing/dart/test_suite.dart

 // Copyright (c) 2012, 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.
 
 /**
  * Classes and methods for enumerating and preparing tests.
  *
  * This library includes:
  *
  * - Creating tests by listing all the Dart files in certain directories,
@@ skipping 360 matching lines @@
     var pkg = configuration['use_public_packages']
         ? 'public_packages' : 'repo_packages';
     return createGeneratedTestDirectoryHelper(
         "pub_package_builds", pkg, directoryOfPubspecYaml, "");
   }
 
   /**
    * Helper function for discovering the packages in the dart repository.
    */
   Future<List> listDir(Path path, Function isValid) {
-    return new Directory(path.toNativePath())
-    .list(recursive: false)
-    .where((fse) => fse is Directory)
-    .map((Directory directory) {
-      var fullPath = directory.absolute.path;
-      var packageName = new Path(fullPath).filename;
-      if (isValid(packageName)) {
-        return [packageName, path.append(packageName).toNativePath()];
-      }
-      return null;
-    })
-    .where((name) => name != null)
-    .toList();
+    var dir = new Directory(path.toNativePath());
+    return dir.exists().then((var exist) {
+      if (!exist) return [];
+      return dir.list(recursive: false)
+      .where((fse) => fse is Directory)
+      .map((Directory directory) {
+        var fullPath = directory.absolute.path;
+        var packageName = new Path(fullPath).filename;
+        if (isValid(packageName)) {
+          return [packageName, path.append(packageName).toNativePath()];
+        }
+        return null;
+      })
+      .where((name) => name != null)
+      .toList();
+      });

[Siggi Cherem (dart-lang), 2014/11/06 17:10:34]

nit: unindent 2

   }
 
   Future<Map> discoverPackagesInRepository() {
     /*
      * Layout of packages inside the dart repository:
      *  dart/
      *      pkg/PACKAGE_NAME
      *      pkg/third_party/PACKAGE_NAME
      *      third_party/pkg/PACKAGE_NAME
      *      runtime/bin/vmservice/PACKAGE_NAME
@@ skipping 1933 matching lines @@
  * $pass tests are expected to pass
  * $failOk tests are expected to fail that we won't fix
  * $fail tests are expected to fail that we should fix
  * $crash tests are expected to crash that we should fix
  * $timeout tests are allowed to timeout
  * $compileErrorSkip tests are skipped on browsers due to compile-time error
 """;
     print(report);
   }
 }