Add a test to verify that analysis server code generation is up to date.

pkg/analysis_server/tool/spec/codegen_matchers.dart

 // Copyright (c) 2014, 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.
 
 /**
  * Code generation for the file "matchers.dart".
  */
 library codegen.matchers;
 
 import 'dart:convert';
-import 'dart:io';
 
 import 'api.dart';
 import 'codegen_tools.dart';
 import 'from_html.dart';
 import 'to_html.dart';
 
 class CodegenMatchersVisitor extends HierarchicalApiVisitor with CodeGenerator {
   /**
    * Visitor used to produce doc comments.
    */
@@ skipping 160 matching lines @@
     });
     write('}');
   }
 
   @override
   void visitTypeReference(TypeReference typeReference) {
     write(camelJoin(['is', typeReference.typeName]));
   }
 }
 
+final GeneratedFile target = new GeneratedFile(
+    '../../test/integration/protocol_matchers.dart', () {
+  CodegenMatchersVisitor visitor = new CodegenMatchersVisitor(readApi());
+  return visitor.collectCode(visitor.visitApi);
+});
+
 /**
  * Translate spec_input.html into protocol_matchers.dart.
  */
 main() {
-  CodegenMatchersVisitor visitor = new CodegenMatchersVisitor(readApi());
-  String code = visitor.collectCode(visitor.visitApi);
-  File outputFile = new File('../../test/integration/protocol_matchers.dart');
-  outputFile.writeAsStringSync(code);
+  target.generate();
 }