Add a utility function to parse annotations in a test file.

lib/src/util/dart.dart

Index: lib/src/util/dart.dart
diff --git a/lib/src/util/dart.dart b/lib/src/util/dart.dart
index 3ee861b23de6263d9a02f0fc307e65994db758dd..76f10b51fa15fb9240e172fbfdedb7fd3a907563 100644
--- a/lib/src/util/dart.dart
+++ b/lib/src/util/dart.dart
@@ -8,6 +8,7 @@ import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
+import 'package:analyzer/analyzer.dart';
 import 'package:path/path.dart' as p;
 
 import 'io.dart';
@@ -70,3 +71,13 @@ void _isolateBuffer(message) {
     });
   });
 }
+
+/// Parse all the annotations at the beginning of a Dart file.
+///
+/// This will parse annotations until the first non-annotation production is
+/// reached.
+List<Annotation> parseAnnotations(String path) {
+  var contents = new File(path).readAsStringSync();
+  var directives = parseDirectives(contents, name: path).directives;
+  return directives.isEmpty ? [] : directives.first.metadata;
+}