Retain elements a finer granularity than library.

dart/tests/compiler/dart2js/message_kind_helper.dart

+// Copyright (c) 2013, 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.
+
+library dart2js.test.message_kind_helper;
+
+import 'package:expect/expect.dart';
+
+import '../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart' show
+    Compiler,
+    MessageKind;
+
+import 'memory_compiler.dart';
+
+const String ESCAPE_REGEXP = r'[[\]{}()*+?.\\^$|]';
+
+Compiler check(MessageKind kind, Compiler cachedCompiler) {
+  Expect.isNotNull(kind.howToFix);
+  Expect.isFalse(kind.examples.isEmpty);
+
+  for (String example in kind.examples) {
+    List<String> messages = <String>[];
+    void collect(Uri uri, int begin, int end, String message, kind) {
+      if (kind.name == 'verbose info') {
+        return;
+      }
+      messages.add(message);
+    }
+
+    Compiler compiler = compilerFor(
+        {'main.dart': example},
+        diagnosticHandler: collect,
+        options: ['--analyze-only'],
+        cachedCompiler: cachedCompiler);
+
+    compiler.run(Uri.parse('memory:main.dart'));
+
+    Expect.isFalse(messages.isEmpty, 'No messages in """$example"""');
+
+    String pattern = '${kind.template}\n${kind.howToFix}'.replaceAllMapped(
+        new RegExp(ESCAPE_REGEXP), (m) => '\\${m[0]}');
+    pattern = pattern.replaceAll(new RegExp(r'#\\\{[^}]*\\\}'), '.*');
+
+    for (String message in messages) {
+      Expect.isTrue(new RegExp('^$pattern\$').hasMatch(message),
+                    '"$pattern" does not match "$message"');
+    }
+    return compiler;
+  }
+}