JSONClient can now preserve OpenStruct type

Until now, OpenStruct in data (or metadata) would be serialized to String.
E.g. `#<OpenStruct a=1>` and returned in such form after reading the
event since no deserialization would occur.

Co-authored-by: Łukasz Reszke <[email protected]>

Author: fidel

rails_event_store/lib/rails_event_store/json_client.rb

@@ -22,7 +22,8 @@ def initialize(
               )
               .register(Date, serializer: ->(v) { v.iso8601 }, deserializer: ->(v) { Date.iso8601(v) })
               .register(DateTime, serializer: ->(v) { v.iso8601 }, deserializer: ->(v) { DateTime.iso8601(v) })
-              .register(BigDecimal, serializer: ->(v) { v.to_s }, deserializer: ->(v) { BigDecimal(v) }),
+              .register(BigDecimal, serializer: ->(v) { v.to_s }, deserializer: ->(v) { BigDecimal(v) })
+              .register(OpenStruct, serializer: ->(v) { v.to_h }, deserializer: ->(v) { OpenStruct.new(v) }),
             RubyEventStore::Mappers::Transformation::SymbolizeMetadataKeys.new
           )
         ),

rails_event_store/spec/json_client_spec.rb

@@ -64,6 +64,13 @@ module RailsEventStore
       expect(client.read.event(event.event_id)).to eq(event)
     end
 
+    specify "reads type of OpenStruct" do
+      event = DummyEvent.new(data: OpenStruct.new(a: 1))
+      client.append(event)
+
+      expect(client.read.event(event.event_id)).to eq(event)
+    end
+
     private
 
     def with_precision(time)