Log input id not library (dart-lang/source_gen#252)

Author: jakemac53

source_gen/source_gen/CHANGELOG.md

@@ -34,6 +34,8 @@ findTokenField(DartObject o) {
   `TypeChecker.firstAnnotationOfExact`. Setting this to `false` will enable you
   to check for matching annotations with incomplete type information (at your
   own risk).
+* Builder logs now log the primary inputs `AssetId` instead of the `library`,
+  which is more useful for tracking down the actual files.
 
 ## 0.6.1+1
 

source_gen/source_gen/lib/src/builder.dart

@@ -199,15 +199,15 @@ Stream<GeneratedOutput> _generate(LibraryElement library,
   var libraryReader = new LibraryReader(library);
   for (var gen in generators) {
     try {
-      log.finer('Running $gen for $library');
+      log.finer('Running $gen for ${buildStep.inputId}');
       var createdUnit = await gen.generate(libraryReader, buildStep);
 
       if (createdUnit != null && createdUnit.isNotEmpty) {
-        log.finest(() => 'Generated $createdUnit for $library');
+        log.finest(() => 'Generated $createdUnit for ${buildStep.inputId}');
         yield new GeneratedOutput(gen, createdUnit);
       }
     } catch (e, stack) {
-      log.severe('Error running $gen for $library.', e, stack);
+      log.severe('Error running $gen for ${buildStep.inputId}.', e, stack);
       yield new GeneratedOutput.fromError(gen, e, stack);
     }
   }

source_gen/source_gen/pubspec.yaml

@@ -15,6 +15,7 @@ dev_dependencies:
   build_test: ^0.6.0
   collection: ^1.1.2
   cli_util: '>=0.1.0 <0.2.0'
+  logging: ^0.11.3
   meta: ^1.0.5
   test: ^0.12.3
   _test_annotations:

source_gen/source_gen/test/builder_test.dart

@@ -6,6 +6,7 @@
 import 'dart:async';
 
 import 'package:build_test/build_test.dart';
+import 'package:logging/logging.dart';
 import 'package:source_gen/source_gen.dart';
 import 'package:test/test.dart';
 
@@ -148,6 +149,16 @@ void main() {
           '$pkgName|lib/a.g.dart': contains(customOutput),
         });
   });
+
+  test('Error logs contain original input ids', () async {
+    var logs = <LogRecord>[];
+    await testBuilder(new LibraryBuilder(new _ThrowingGenerator()),
+        {'$pkgName|lib/a.dart': 'void hello() {}'},
+        onLog: logs.add);
+    await new Future(() {});
+    expect(
+        logs.map((l) => l.message), contains(contains('$pkgName|lib/a.dart')));
+  });
 }
 
 Future _generateTest(CommentGenerator gen, String expectedContent) async {
@@ -182,6 +193,10 @@ class _BadOutputGenerator extends Generator {
   Future<String> generate(LibraryReader library, _) async => 'not valid code!';
 }
 
+class _ThrowingGenerator extends Generator {
+  Future<String> generate(_, __) async => throw new UnimplementedError();
+}
+
 const pkgName = 'pkg';
 
 const _testLibContent = r'''