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protoc_plugin/test/file_generator_test.dart

diff --git a/protoc_plugin/test/file_generator_test.dart b/protoc_plugin/test/file_generator_test.dart
index ae9805c..34d9e9a 100644
--- a/protoc_plugin/test/file_generator_test.dart
+++ b/protoc_plugin/test/file_generator_test.dart
@@ -350,6 +350,9 @@
 
     final writer = IndentingWriter(filename: '');
     fg.writeMainHeader(writer);
+    // We use a '.~dart' file extension here, insead of '.dart', so that
+    // 'pub publish' won't try and validate that all the imports for this file
+    // are listed in the pubspec.
     expectGolden(fg.generateGrpcFile(), 'grpc_service.pbgrpc.~dart');
   });