Run pub tests against older versions of barback.

sdk/lib/_internal/pub/test/serve/allows_arbitrary_modes_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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 pub_tests;
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import '../serve/utils.dart';
 
@@ skipping 13 matching lines @@
     return new Future.value().then((_) {
       var id = transform.primaryInput.id.changeExtension(".out");
       transform.addOutput(new Asset.fromString(id, settings.mode.toString()));
     });
   }
 }
 """;
 
 main() {
   initConfig();
-  integration("allows user-defined mode names", () {
-    d.dir(appPath, [
-      d.pubspec({
-        "name": "myapp",
-        "transformers": ["myapp/src/transformer"]
-      }),
-      d.dir("lib", [d.dir("src", [
-        d.file("transformer.dart", TRANSFORMER)
-      ])]),
-      d.dir("web", [
-        d.file("foo.txt", "foo")
-      ])
-    ]).create();
+  withBarbackVersions("any", () {
+    integration("allows user-defined mode names", () {
+      d.dir(appPath, [
+        d.pubspec({
+          "name": "myapp",
+          "transformers": ["myapp/src/transformer"]
+        }),
+        d.dir("lib", [d.dir("src", [
+          d.file("transformer.dart", TRANSFORMER)
+        ])]),
+        d.dir("web", [
+          d.file("foo.txt", "foo")
+        ])
+      ]).create();
 
-    createLockFile('myapp', pkg: ['barback']);
+      createLockFile('myapp', pkg: ['barback']);
 
-    pubServe(args: ["--mode", "depeche"]);
-    requestShouldSucceed("foo.out", "depeche");
-    endPubServe();
+      pubServe(args: ["--mode", "depeche"]);
+      requestShouldSucceed("foo.out", "depeche");
+      endPubServe();
+    });
   });
 }