Support transformers that depend on other transformers.

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

Index: sdk/lib/_internal/pub/test/serve/runs_one_third_party_transformer_on_another_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/runs_one_third_party_transformer_on_another_test.dart b/sdk/lib/_internal/pub/test/serve/runs_one_third_party_transformer_on_another_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..96732e907b6a657145f7bad699b56dbdea01e380
--- /dev/null
+++ b/sdk/lib/_internal/pub/test/serve/runs_one_third_party_transformer_on_another_test.dart
@@ -0,0 +1,54 @@
+// 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 'utils.dart';
+
+main() {
+  initConfig();
+  integration("runs one third-party transformer on another", () {
+    d.dir("foo", [
+      d.pubspec({
+        "name": "foo",
+        "version": "1.0.0"
+      }),
+      d.dir("lib", [
+        d.file("transformer.dart", dartTransformer('foo')),
+      ])
+    ]).create();
+
+    d.dir("bar", [
+      d.pubspec({
+        "name": "bar",
+        "version": "1.0.0",
+        "transformers": ["foo/transformer"],
+        "dependencies": {"foo": {"path": "../foo"}}
+      }),
+      d.dir("lib", [
+        d.file("transformer.dart", dartTransformer('bar')),
+      ])
+    ]).create();
+
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "transformers": ["bar/transformer"],
+        "dependencies": {'bar': {'path': '../bar'}}
+      }),
+      d.dir("web", [
+        d.file("main.dart", 'const TOKEN = "main.dart";')
+      ])
+    ]).create();
+
+    createLockFile('myapp', sandbox: ['foo', 'bar'], pkg: ['barback']);
+
+    startPubServe();
+    requestShouldSucceed("main.dart",
+        'const TOKEN = "(main.dart, (bar, foo))";');
+    endPubServe();
+  });
+}