makes tests faster, see #304

test/codegen_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.
 
 /// Tests code generation.
 /// Runs Dart Dev Compiler on all input in the `codegen` directory and checks
 /// that the output is what we expected.
 library dev_compiler.test.codegen_test;
 
 import 'dart:io';
@@ skipping 58 matching lines @@
             forceCompile: checkSdk),
         useColors: false,
         checkSdk: checkSdk,
         runtimeDir: runtimeDir,
         inputs: [entryPoint],
         inputBaseDir: inputDir);
     var reporter = createErrorReporter(context, options);
     return new BatchCompiler(context, options, reporter: reporter).run();
   }
 
-  // Remove old output, and `packages` symlinks which mess up the diff.
-  var dir = new Directory(expectDir);
-  if (dir.existsSync()) dir.deleteSync(recursive: true);
-  var packagesDirs = new Directory(inputDir)
-      .listSync(recursive: true)
-      .where((d) => d is Directory && path.basename(d.path) == 'packages');
-  packagesDirs.forEach((d) => d.deleteSync());
-
   {
     // Expand wacky multitests into a bunch of test files.
     // We'll compile each one as if it was an input.
     var languageDir = path.join(inputDir, 'language');
     var testFiles = _findTests(languageDir, filePattern);
 
     for (var filePath in testFiles) {
       if (filePath.endsWith('_multi.dart')) continue;
 
       var contents = new File(filePath).readAsStringSync();
@@ skipping 146 matching lines @@
     print('[AnalysisEngine] error $message $exception');
   }
 
   @override void logError2(String message, Object exception) {
     print('[AnalysisEngine] error $message $exception');
   }
 
   void logInformation(String message, [CaughtException exception]) {}
   void logInformation2(String message, Object exception) {}
 }