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packages/barback/test/transformer/check_content.dart

Index: packages/barback/test/transformer/check_content.dart
diff --git a/packages/barback/test/transformer/check_content.dart b/packages/barback/test/transformer/check_content.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 barback.test.transformer.check_content;
+
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+
+import 'mock.dart';
+
+/// A transformer that modifies assets that contains the given content.
+class CheckContentTransformer extends MockTransformer {
+  final Pattern content;
+  final String addition;
+
+  CheckContentTransformer(this.content, this.addition);
+
+  bool doIsPrimary(AssetId id) => true;
+
+  Future doApply(Transform transform) {
+    return getPrimary(transform).then((primary) {
+      return primary.readAsString().then((value) {
+        if (!value.contains(content)) return;
+
+        transform.addOutput(
+            new Asset.fromString(primary.id, "$value$addition"));
+      });
+    });
+  }
+}