Add Rackstash::Fields::Array#<< to add a value at the end of the array

lib/rackstash/fields/array.rb

@@ -20,6 +20,17 @@ module Rackstash
         @raw[index] = normalize(value)
       end
 
+      # Add a given value at the end of the array
+      #
+      # @param value [#call, Object] any value which can be serialized to JSON.
+      #   The value will be normalized before being added so that only JSON-
+      #   compatible objects are added into the array.
+      # @return [self]
+      def <<(value)
+        @raw << normalize(value)
+        self
+      end
+
       def as_json(*)
         @raw.map { |value|
           value.is_a?(AbstractCollection) ? value.as_json : value

spec/rackstash/fields/array_spec.rb

@@ -30,6 +30,24 @@ describe Rackstash::Fields::Array do
     end
   end
 
+  describe '#<<' do
+    it 'normalized the value' do
+      expect(array).to receive(:normalize).with('value').twice.and_return('normalized')
+
+      array << 'value'
+      expect(array[0]).to eql 'normalized'
+      expect(array[1]).to be nil
+
+      array << 'value'
+      expect(array[0]).to eql 'normalized'
+      expect(array[1]).to eql 'normalized'
+    end
+
+    it 'returns the array' do
+      expect(array << 'value').to equal array
+    end
+  end
+
   describe '#as_json' do
     before do
       array[0] = 'value'