Ensure DomainEvent transformation does not change passed event

#1002
RailsEventStore · Feb 27, 2021 · 3ba0549 · 3ba0549
1 parent bb8af1f
commit 3ba0549
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Showing 2 changed files with 26 additions and 2 deletions.
diff --git a/ruby_event_store/lib/ruby_event_store/mappers/transformation/domain_event.rb b/ruby_event_store/lib/ruby_event_store/mappers/transformation/domain_event.rb
@@ -5,9 +5,9 @@ module Mappers
     module Transformation
       class DomainEvent
         def dump(domain_event)
-          metadata = domain_event.metadata.to_h
+          metadata  = domain_event.metadata.dup.to_h
           timestamp = metadata.delete(:timestamp)
-          valid_at = metadata.delete(:valid_at)
+          valid_at  = metadata.delete(:valid_at)
           Record.new(
             event_id:   domain_event.event_id,
             metadata:   metadata,

diff --git a/ruby_event_store/spec/mappers/transformation/domain_event_spec.rb b/ruby_event_store/spec/mappers/transformation/domain_event_spec.rb
@@ -36,6 +36,30 @@ module Transformation
           expect(loaded).to eq(event)
           expect(loaded.metadata.to_h).to eq(event.metadata.to_h)
         end
+
+        specify "does not mutate custom event" do
+          event_klass = Class.new do
+            def initialize(data, metadata)
+              @event_id = SecureRandom.uuid
+              @data     = data
+              @metadata = metadata
+            end
+
+            attr_reader :event_id, :data, :metadata
+
+            def event_type
+              "bazinga"
+            end
+          end
+
+          DomainEvent.new.dump(event = event_klass.new(
+            {some: 'data'},
+            {some: 'meta', valid_at: time, timestamp: time}
+          ))
+
+          expect(event.data).to      eq({some: 'data'})
+          expect(event.metadata).to  eq({some: 'meta', valid_at: time, timestamp: time})
+        end
       end
     end
   end