Polymer transformer logs now show on the frontend for pub serve.

pkg/polymer/test/build/common.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 polymer.test.build.common;
 
 import 'dart:async';
 
 import 'package:barback/barback.dart';
+import 'package:polymer/src/build/common.dart';
 import 'package:stack_trace/stack_trace.dart';
 import 'package:unittest/unittest.dart';
 
 String idToString(AssetId id) => '${id.package}|${id.path}';
 AssetId idFromString(String s) {
   int index = s.indexOf('|');
   return new AssetId(s.substring(0, index), s.substring(index + 1));
 }
 
 String _removeTrailingWhitespace(String str) =>
@@ skipping 101 matching lines @@
       if (messages == null) return;
       expect(messagesSeen, messages.length,
           reason: 'less messages than expected');
     });
   }
 }
 
 testPhases(String testName, List<List<Transformer>> phases,
     Map<String, String> inputFiles, Map<String, String> expectedFiles,
     [List<String> expectedMessages, bool solo = false]) {
-
   // Include mock versions of the polymer library that can be used to test
   // resolver-based code generation.
   POLYMER_MOCKS.forEach((file, contents) { inputFiles[file] = contents; });
   (solo ? solo_test : test)(testName, () {
     var helper = new TestHelper(phases, inputFiles, expectedMessages)..run();
     return helper.checkAll(expectedFiles).whenComplete(() => helper.tearDown());
   });
 }
 
 solo_testPhases(String testName, List<List<Transformer>> phases,
     Map<String, String> inputFiles, Map<String, String> expectedFiles,
     [List<String> expectedMessages]) =>
   testPhases(testName, phases, inputFiles, expectedFiles, expectedMessages,
       true);
 
+
+// Similar to testPhases, but tests all the cases around log behaviour in
+// different modes. Any expectedFiles with [LOG_EXTENSION] will be removed from
+// the expectation as appropriate, and any error logs will be changed to expect
+// warning logs as appropriate.
+testLogOutput(Function buildPhase, String testName,
+              Map<String, String> inputFiles, Map<String, String> expectedFiles,
+              [List<String> expectedMessages, bool solo = false]) {
+
+  final transformOptions = [
+      new TransformOptions(injectBuildLogsInOutput: false, releaseMode: false),
+      new TransformOptions(injectBuildLogsInOutput: false, releaseMode: true),
+      new TransformOptions(injectBuildLogsInOutput: true, releaseMode: false),
+      new TransformOptions(injectBuildLogsInOutput: true, releaseMode: true),
+  ];
+
+  for (var options in transformOptions) {
+    var phase = buildPhase(options);
+    var actualExpectedFiles = {};
+    expectedFiles.forEach((file, content) {
+      if (file.contains(LOG_EXTENSION)
+      && (!options.injectBuildLogsInOutput || options.releaseMode)) {
+        return;
+      }
+      actualExpectedFiles[file] = content;
+    });
+    var fullTestName = '$testName: '
+    'injectLogs=${options.injectBuildLogsInOutput} '
+    'releaseMode=${options.releaseMode}';
+    testPhases(
+        fullTestName, [[phase]], inputFiles,
+        actualExpectedFiles,
+        expectedMessages.map((m) =>
+            options.releaseMode ? m : m.replaceFirst('error:', 'warning:'))
+            .toList(),
+        solo);
+  }
+}
+
 /// Generate an expected ._data file, where all files are assumed to be in the
 /// same [package].
 String expectedData(List<String> urls, {package: 'a', experimental: false}) {
   var ids = urls.map((e) => '["$package","$e"]').join(',');
   return '{"experimental_bootstrap":$experimental,"script_ids":[$ids]}';
 }
 
 const EMPTY_DATA = '{"experimental_bootstrap":false,"script_ids":[]}';
 
 const WEB_COMPONENTS_TAG =
@@ skipping 45 matching lines @@
 
   'observe|lib/observe.dart':
       'library observe;\n'
       'export "src/metadata.dart";',
 
   'observe|lib/src/metadata.dart':
       'library observe.src.metadata;\n'
       'class ObservableProperty { const ObservableProperty(); }\n'
       'const observable = const ObservableProperty();\n',
 };