feat(6178): emit ruby enum as integer

ruby/ext/google/protobuf_c/message.c

@@ -1164,6 +1164,11 @@ static VALUE Message_encode_json(int argc, VALUE* argv, VALUE klass) {
                               Qfalse))) {
       options |= upb_JsonEncode_EmitDefaults;
     }
+
+    if (RTEST(rb_hash_lookup2(hash_args, ID2SYM(rb_intern("enums_as_integers")),
+                              Qfalse))) {
+      options |= upb_JsonEncode_FormatEnumsAsIntegers;
+    }
   }
 
   upb_Status_Clear(&status);

ruby/tests/encode_decode_test.rb

@@ -84,6 +84,34 @@ class EncodeDecodeTest < Test::Unit::TestCase
     )
 
     assert_match 'optional_int32', json
+
+
+    # Test for enums printing as ints.
+    msg = A::B::C::TestMessage.new({ optional_enum: 1 })
+    json = A::B::C::TestMessage.encode_json(
+      msg, 
+      { :enums_as_integers => true }
+    )
+
+    assert_match '"optionalEnum":1', json
+
+    # Test for default enum being printed as int.
+    msg = A::B::C::TestMessage.new({ optional_enum: 0 })
+    json = A::B::C::TestMessage.encode_json(
+      msg, 
+      { :enums_as_integers => true, :emit_defaults => true }
+    )
+
+    assert_match '"optionalEnum":0', json
+
+    # Test for repeated enums printing as ints.
+    msg = A::B::C::TestMessage.new({ repeated_enum: [0,1,2,3] })
+    json = A::B::C::TestMessage.encode_json(
+      msg, 
+      { :enums_as_integers => true }
+    )
+
+    assert_match '"repeatedEnum":[0,1,2,3]', json
   end
 
   def test_encode_wrong_msg