First stab at "pub run" command.

sdk/lib/_internal/pub/test/run/displays_transformer_logs_test.dart

Index: sdk/lib/_internal/pub/test/run/displays_transformer_logs_test.dart
diff --git a/sdk/lib/_internal/pub/test/run/displays_transformer_logs_test.dart b/sdk/lib/_internal/pub/test/run/displays_transformer_logs_test.dart
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+++ b/sdk/lib/_internal/pub/test/run/displays_transformer_logs_test.dart
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+// Copyright (c) 2014, 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.
+
+import 'package:scheduled_test/scheduled_test.dart';
+
+import '../descriptor.dart' as d;
+import '../test_pub.dart';
+import 'utils.dart';
+
+const SCRIPT = """
+import "package:myapp/lib.dart";
+main() {
+  callLib();
+}
+""";
+
+const LIB = """
+callLib() {
+  print("lib");
+}
+""";
+
+// Make it lazy so that "lib.dart" isn't transformed until after the process
+// is started. Otherwise, since this tranformer modifies .dart files, it will
+// be run while the transformers themselves are loading during pub run's
+// startup.
+const TRANSFORMER = """
+import 'dart:async';
+
+import 'package:barback/barback.dart';
+
+class LoggingTransformer extends Transformer implements LazyTransformer {
+  LoggingTransformer.asPlugin();
+
+  String get allowedExtensions => '.dart';
+
+  void apply(Transform transform) {
+    transform.logger.info('\${transform.primaryInput.id}.');
+    transform.logger.warning('\${transform.primaryInput.id}.');
+  }
+
+  void declareOutputs(DeclaringTransform transform) {
+    // TODO(rnystrom): Remove this when #19408 is fixed.
+    transform.declareOutput(transform.primaryId);
+  }
+}
+""";
+
+main() {
+  initConfig();
+  withBarbackVersions("any", () {
+    integration('displays transformer log messages', () {
+      d.dir(appPath, [
+        d.pubspec({
+          "name": "myapp",
+          "transformers": ["myapp/src/transformer"]
+        }),
+        d.dir("lib", [
+          d.file("lib.dart", LIB),
+          d.dir("src", [
+            d.file("transformer.dart", TRANSFORMER)
+          ])
+        ]),
+        d.dir("bin", [
+          d.file("script.dart", SCRIPT)
+        ])
+      ]).create();
+
+      createLockFile('myapp', pkg: ['barback']);
+
+      var pub = pubRun(args: ["script"],
+          transformers: ["myapp/src/transformer"]);
+
+      // Note that the info log is only displayed here because the test
+      // harness runs pub in verbose mode. By default, only the warning would
+      // be shown.
+      pub.stdout.expect("[Info from Logging]:");
+      pub.stdout.expect("myapp|bin/script.dart.");
+
+      pub.stderr.expect("[Warning from Logging]:");
+      pub.stderr.expect("myapp|bin/script.dart.");
+
+      pub.stdout.expect("[Info from Logging]:");
+      pub.stdout.expect("myapp|lib/lib.dart.");
+
+      pub.stderr.expect("[Warning from Logging]:");
+      pub.stderr.expect("myapp|lib/lib.dart.");
+
+      pub.stdout.expect("lib");
+      pub.shouldExit();
+    });
+  });
+}