Freeze the raw object along the wrapper for all fields

lib/rackstash/fields/abstract_collection.rb

@@ -29,6 +29,16 @@ module Rackstash
       end
       alias eql? ==
 
+      # Prevents further modifications to `self`. A `RuntimeError` will be
+      # raised if modification is attempted. There is no way to unfreeze a
+      # frozen object.
+      #
+      # @return [self]
+      def freeze
+        raw.freeze
+        super
+      end
+
       # Compute a hash-code for this collection.
       #
       # Two collections with the same raw content will have the same hash code

spec/rackstash/fields/abstract_collection_spec.rb

@@ -92,6 +92,20 @@ describe Rackstash::Fields::AbstractCollection do
     end
   end
 
+  describe '#freeze' do
+    it 'freezes the collection and the raw data' do
+      raw = [123, 'foo']
+      collection.send(:raw=, raw)
+
+      expect(raw).not_to be_frozen
+
+      collection.freeze
+
+      expect(collection).to be_frozen
+      expect(raw).to be_frozen
+    end
+  end
+
   describe '#hash' do
     it 'returns the same hash for the same raw content' do
       collection.send(:raw=, [123, 'foo'])