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packages/stack_trace/test/utils.dart

Index: packages/stack_trace/test/utils.dart
diff --git a/packages/stack_trace/test/utils.dart b/packages/stack_trace/test/utils.dart
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+// 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 stack_trace.test.utils;
+
+import 'package:test/test.dart';
+
+/// Returns a matcher that runs [matcher] against a [Frame]'s `member` field.
+Matcher frameMember(matcher) =>
+  transform((frame) => frame.member, matcher, 'member');
+
+/// Returns a matcher that runs [matcher] against a [Frame]'s `library` field.
+Matcher frameLibrary(matcher) =>
+  transform((frame) => frame.library, matcher, 'library');
+
+/// Returns a matcher that runs [transformation] on its input, then matches
+/// the output against [matcher].
+///
+/// [description] should be a noun phrase that describes the relation of the
+/// output of [transformation] to its input.
+Matcher transform(transformation(value), matcher, String description) =>
+  new _TransformMatcher(transformation, wrapMatcher(matcher), description);
+
+class _TransformMatcher extends Matcher {
+  final Function _transformation;
+  final Matcher _matcher;
+  final String _description;
+
+  _TransformMatcher(this._transformation, this._matcher, this._description);
+
+  bool matches(item, Map matchState) =>
+    _matcher.matches(_transformation(item), matchState);
+
+  Description describe(Description description) =>
+    description.add(_description).add(' ').addDescriptionOf(_matcher);
+}