Support extensions with multiple periods in Transformer.allowedExtensions.

pkg/barback/test/transformer_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.
 
 library barback.test.transformer_test;
 
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 import 'package:unittest/unittest.dart';
 
 import 'utils.dart';
 
 main() {
   initConfig();
 
   group("isPrimary", () {
     test("defaults to allowedExtensions", () {
       var transformer = new ExtensionTransformer(".txt .bin");
       expect(transformer.isPrimary(makeAsset("foo.txt")),
           completion(isTrue));
 
       expect(transformer.isPrimary(makeAsset("foo.bin")),
           completion(isTrue));
 
       expect(transformer.isPrimary(makeAsset("foo.nottxt")),
           completion(isFalse));
     });
 
+    test("supports multi-level extensions with allowedExtensions", () {
+      var transformer = new ExtensionTransformer(".dart.js");
+      expect(transformer.isPrimary(makeAsset("foo.dart.js")),
+          completion(isTrue));
+
+      expect(transformer.isPrimary(makeAsset("foo.js")), completion(isFalse));
+      expect(transformer.isPrimary(makeAsset("foo.dart")), completion(isFalse));
+    });
+
+    test("throws an error for extensions without periods", () {
+      expect(() => new ExtensionTransformer("dart"), throwsFormatException);
+    });
+
     test("allows all files if allowedExtensions is not overridden", () {
       var transformer = new MockTransformer();
       expect(transformer.isPrimary(makeAsset("foo.txt")),
           completion(isTrue));
 
       expect(transformer.isPrimary(makeAsset("foo.bin")),
           completion(isTrue));
 
       expect(transformer.isPrimary(makeAsset("anything")),
           completion(isTrue));
@@ skipping 10 matching lines @@
   Future apply(Transform transform) => new Future.value();
 }
 
 class ExtensionTransformer extends Transformer {
   final String allowedExtensions;
 
   ExtensionTransformer(this.allowedExtensions);
 
   Future apply(Transform transform) => new Future.value();
 }