Support declaring and lazy transformers in pub.

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

Index: sdk/lib/_internal/pub/test/serve/supports_user_defined_declaring_transformers.dart
diff --git a/sdk/lib/_internal/pub/test/serve/supports_user_defined_declaring_transformers.dart b/sdk/lib/_internal/pub/test/serve/supports_user_defined_declaring_transformers.dart
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index 0000000000000000000000000000000000000000..d066b2d81ae69b5fc854195b693c6f98ddca11af
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+++ b/sdk/lib/_internal/pub/test/serve/supports_user_defined_declaring_transformers.dart
@@ -0,0 +1,96 @@
+// Copyright (c) 2014, 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';
+
+const LAZY_TRANSFORMER = """
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+
+class LazyRewriteTransformer extends Transformer implements LazyTransformer {
+  LazyRewriteTransformer.asPlugin();
+
+  String get allowedExtensions => '.in';
+
+  Future apply(Transform transform) {
+    transform.logger.info('Rewriting \${transform.primaryInput.id}.');
+    return transform.primaryInput.readAsString().then((contents) {
+      var id = transform.primaryInput.id.changeExtension(".mid");
+      transform.addOutput(new Asset.fromString(id, "\$contents.mid"));
+    });
+  }
+
+  Future declareOutputs(DeclaringTransform transform) {
+    transform.declareOutput(transform.primaryId.changeExtension(".mid"));
+    return new Future.value();
+  }
+}
+""";
+
+const DECLARING_TRANSFORMER = """
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+
+class DeclaringRewriteTransformer extends Transformer
+    implements DeclaringTransformer {
+  DeclaringRewriteTransformer.asPlugin();
+
+  String get allowedExtensions => '.mid';
+
+  Future apply(Transform transform) {
+    transform.logger.info('Rewriting \${transform.primaryInput.id}.');
+    return transform.primaryInput.readAsString().then((contents) {
+      var id = transform.primaryInput.id.changeExtension(".final");
+      transform.addOutput(new Asset.fromString(id, "\$contents.final"));
+    });
+  }
+
+  Future declareOutputs(DeclaringTransform transform) {
+    transform.declareOutput(transform.primaryId.changeExtension(".final"));
+    return new Future.value();
+  }
+}
+""";
+
+main() {
+  initConfig();
+  integration("supports a user-defined declaring transformer", () {
+    d.dir(appPath, [
+      d.pubspec({
+        "name": "myapp",
+        "transformers": ["myapp/src/lazy", "myapp/src/declaring"]
+      }),
+      d.dir("lib", [d.dir("src", [
+        // Include a lazy transformer before the declaring transformer, because
+        // otherwise its behavior is indistinguishable from a normal
+        // transformer.
+        d.file("lazy.dart", LAZY_TRANSFORMER),
+        d.file("declaring.dart", DECLARING_TRANSFORMER)
+      ])]),
+      d.dir("web", [
+        d.file("foo.in", "foo")
+      ])
+    ]).create();
+
+    createLockFile('myapp', pkg: ['barback']);
+
+    var server = pubServe();
+    // The build should complete without either transformer logging anything.
+    server.stdout.expect('Build completed successfully');
+
+    requestShouldSucceed("foo.final", "foo.mid.final");
+    server.stdout.expect(emitsLines(
+        '[Info from LazyRewrite]:\n'
+        'Rewriting myapp|web/foo.in.\n'
+        '[Info from DeclaringRewrite]:\n'
+        'Rewriting myapp|web/foo.mid.'));
+    endPubServe();
+  });
+}