* Fix most of the unused variable warnings in Ruby tests * Add encoded_field_b back in tests/common_tests.rb
* Check the message to be encoded is the wrong type. (#4885) * Change TypeError to ArgumentError
* Add discard unknown API in ruby. * Add test for oneof message field. * Add TestUnknown to represent unknown field data clearly. * Only serialize the message with unknown fields itself in test. * Move discard_unknown from Message to Google.Protobuf