update transformer-test dep

lib/src/transformer/transformer.dart

@@ -17,7 +17,10 @@ import '../builder/build_step_impl.dart';
 /// A [Transformer] which runs multiple [Builder]s.
 /// Extend this class and define the [builders] getter to create a [Transformer]
 /// out of your custom [Builder]s.
-abstract class BuilderTransformer implements Transformer {
+///
+/// By default all [BuilderTransformer]s are [DeclaringTransformer]s. If you
+/// wish to run as a [LazyTransformer], simply mix that into your class as well.
+abstract class BuilderTransformer implements Transformer, DeclaringTransformer {
   /// The only thing you need to implement when extending this class. This
   /// declares which builders should be ran.
   ///
@@ -71,6 +74,13 @@ abstract class BuilderTransformer implements Transformer {
       await buildStep.outputsCompleted;
     }));
   }
+
+  @override
+  void declareOutputs(DeclaringTransform transform) {
+    for (var outputId in _expectedOutputs(transform.primaryId, builders)) {
+      transform.declareOutput(_toBarbackAssetId(outputId));
+    }
+  }
 }
 
 /// Very simple [AssetReader] which uses a [Transform].

pubspec.yaml

@@ -16,4 +16,4 @@ dependencies:
 
 dev_dependencies:
   test: ^0.12.0
-  transformer_test: ^0.1.0
+  transformer_test: ^0.2.0

test/transformer/transformer_test.dart

@@ -48,7 +48,7 @@ main() {
     ],
   ], {
     'a|web/a.txt': 'hello',
-  }, {}, [
+  }, {}, messages: [
     _fileExistsError('CopyBuilder', ['a|web/a.txt.copy']),
   ]);
 
@@ -80,23 +80,18 @@ main() {
   ], {
     'a|web/a.txt': 'hello',
     'a|web/a.txt.copy': 'hello',
-  }, {}, [
+  }, {}, messages: [
     _fileExistsError("CopyBuilder", ["a|web/a.txt.copy"]),
-  ]);
+  ], expectBarbackErrors: true);
 
-  // TODO(jakemac): Skipped because we can't detect this situation today.
-  // Instead you get a barback error, see
-  // https://github.com/dart-lang/transformer_test/issues/2
-  //
-  // testPhases('builders in the same phase can\'t output the same file', [
-  //   [singleCopyTransformer, new GenericBuilderTransformer([new CopyBuilder()])]
-  // ], {
-  //   'a|web/a.txt': 'hello',
-  // }, {
-  //   'a|web/a.txt.copy': 'hello',
-  // }, [
-  //   _fileExistsError("CopyBuilder", ["a|web/a.txt.copy"]),
-  // ]);
+  // Gives a barback error only, we can't detect this situation.
+  testPhases('builders in the same phase can\'t output the same file', [
+    [singleCopyTransformer, new GenericBuilderTransformer([new CopyBuilder()])]
+  ], {
+    'a|web/a.txt': 'hello',
+  }, {
+    'a|web/a.txt.copy': 'hello',
+  }, expectBarbackErrors: true);
 
   testPhases('builders in separate phases can\'t output the same file', [
     [singleCopyTransformer],
@@ -105,9 +100,9 @@ main() {
     'a|web/a.txt': 'hello',
   }, {
     'a|web/a.txt.copy': 'hello',
-  }, [
+  }, messages: [
     _fileExistsError("CopyBuilder", ["a|web/a.txt.copy"]),
-  ]);
+  ], expectBarbackErrors: true);
 }
 
 String _fileExistsError(String builder, List<String> files) {