Add discard unknown API in ruby. (#3990)

* 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

1 files changed, 13 insertions, 0 deletions

diff --git a/ruby/tests/generated_code.proto b/ruby/tests/generated_code.proto
index 62fd83ed..3b934bd6 100644
--- a/ruby/tests/generated_code.proto
+++ b/ruby/tests/generated_code.proto
@@ -57,6 +57,9 @@ message TestMessage {
   }
 
   NestedMessage nested_message = 80;
+
+  // Reserved for non-existing field test.
+  // int32 non_exist = 89;
 }
 
 enum TestEnum {
@@ -65,3 +68,13 @@ enum TestEnum {
   B = 2;
   C = 3;
 }
+
+message TestUnknown {
+  TestUnknown optional_unknown = 11;
+  repeated TestUnknown repeated_unknown = 31;
+  oneof my_oneof {
+    TestUnknown oneof_unknown = 51;
+  }
+  map<string, TestUnknown> map_unknown = 67;
+  int32 unknown_field = 89;
+}