Sometimes tests encode unreal situations

* mutant signalled some unhandled mutations around key.to_s

* which lead to the investigation that we should not need key.to_s at
  all

* the reason we have to do it is because of the tests,
  transformation tested on their own do not pass through
  SymbolizeMetadaKeys which is part of every mapper — when such
  transformation is not present as part of the pipeline the keys wound
  not be symbols: thus the key.to_s fallback

Author: mostlyobvious

ruby_event_store/lib/ruby_event_store/mappers/transformation/preserve_types.rb

@@ -143,7 +143,7 @@ def restore_type(argument, type)
           case type
           when Hash
             argument.reduce({}) do |hash, (key, value)|
-              key_type, value_type = type.fetch(key.to_sym) { type.fetch(key.to_s) }
+              key_type, value_type = type.fetch(key.to_sym)
               hash.merge(restore_type(key, key_type) => restore_type(value, value_type))
             end
           when Array

ruby_event_store/spec/mappers/transformation/preserve_types_spec.rb

@@ -35,6 +35,7 @@ module Transformation
             valid_at: time,
           )
         end
+
         let(:dump_of_record) do
           Record.new(
             event_id: uuid,
@@ -337,16 +338,14 @@ module Transformation
               event_id: uuid,
               metadata: {
               },
-              data: {
-                active_support_time_with_zone: active_support_time_with_zone,
-              },
+              data: active_support_time_with_zone,
               event_type: "TestEvent",
               timestamp: nil,
               valid_at: nil,
             )
 
           expect(transformation.dump(record).metadata[:types]).to eq(
-            { data: { "active_support_time_with_zone" => %w[Symbol ActiveSupport::TimeWithZone] }, metadata: {} },
+            { data: "ActiveSupport::TimeWithZone", metadata: {} },
           )
           expect(transformation.load(transformation.dump(record))).to eq(record)
         ensure