Detect Go files generated by Protocol Buffers

lib/linguist/generated.rb

@@ -62,6 +62,7 @@ module Linguist
       generated_parser? ||
       generated_net_docfile? ||
       generated_postscript? ||
+      generated_protocol_buffer_go? ||
       generated_protocol_buffer? ||
       generated_jni_header? ||
       vcr_cassette?
@@ -202,6 +203,13 @@ module Linguist
         creator.include?("ImageMagick")
     end
 
+    def generated_protocol_buffer_go?
+      return false unless extname == '.go'
+      return false unless lines.count > 1
+
+      return lines[0].include?("Code generated by protoc-gen-go")
+    end
+
     # Internal: Is the blob a C++, Java or Python source file generated by the
     # Protocol Buffer compiler?
     #

test/test_blob.rb

@@ -216,6 +216,7 @@ class TestBlob < Minitest::Test
     assert sample_blob("C++/protocol-buffer.pb.cc").generated?
     assert sample_blob("Java/ProtocolBuffer.java").generated?
     assert sample_blob("Python/protocol_buffer_pb2.py").generated?
+    assert sample_blob("Go/api.pb.go").generated?
 
     # Generated JNI
     assert sample_blob("C/jni_layer.h").generated?