Implement ClassMirror.metadata.

dart/tests/lib/mirrors/metadata_test.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.
 
 @fisk @symbol
 library test.metadata_test;
 
 import 'dart:mirrors';
 
 const fisk = 'a metadata string';
 
 const symbol = const Symbol('fisk');
 
+@symbol @fisk
+class MyClass {
+}
+
+checkMetadata(DeclarationMirror mirror, List expectedMetadata) {
+  List metadata = mirror.metadata.map((m) => m.reflectee).toList();
+  if (metadata == null) {
+    throw 'Null metadata on $mirror';
+  }
+  int expectedLength = expectedMetadata.length;
+  int actualLength = metadata.length;
+  if (expectedLength != actualLength) {
+    throw 'Expected length = $expectedLength, but got length = $actualLength.';
+  }
+  for (int i = 0; i < expectedLength; i++) {
+    if (metadata[i] != expectedMetadata[i]) {
+      throw '${metadata[i]} is not "${expectedMetadata[i]}"'
+          ' in $mirror at index $i';
+    }
+  }
+  print(metadata);
+}
+
 main() {
-  MirrorSystem mirrors = currentMirrorSystem();
-  LibraryMirror library =
-      mirrors.findLibrary(const Symbol('test.metadata_test')).first;
-  List metadata = library.metadata.map((m) => m.reflectee).toList();
-  if (metadata.length != 2) {
-    throw 'Expected two pieces of metadata on library';
-  }
-  if (!metadata.contains(fisk)) {
-    throw '$metadata does not contain "$fisk"';
-  }
-  if (!metadata.contains(symbol)) {
-    throw '$metadata does not contain "$symbol"';
-  }
   if (MirrorSystem.getName(symbol) != 'fisk') {
     // This happened in dart2js due to how early library metadata is
     // computed.
     throw 'Bad constant: $symbol';
   }
-  print(metadata);
+
+  MirrorSystem mirrors = currentMirrorSystem();
+  checkMetadata(mirrors.findLibrary(const Symbol('test.metadata_test')).first,
+                [fisk, symbol]);
+  checkMetadata(reflect(new MyClass()).type, [symbol, fisk]);
 }