Implement a key/value registry at env level

lib/producer/core/env.rb

@@ -1,18 +1,27 @@
 module Producer
   module Core
     class Env
-      attr_reader   :input, :output
+      attr_reader   :input, :output, :registry
       attr_accessor :target
 
-      def initialize(input: $stdin, output: $stdout)
-        @input  = input
-        @output = output
-        @target = nil
+      def initialize(input: $stdin, output: $stdout, registry: {})
+        @input    = input
+        @output   = output
+        @target   = nil
+        @registry = registry
       end
 
       def remote
         @remote ||= Remote.new(target)
       end
+
+      def [](key)
+        @registry[key]
+      end
+
+      def []=(key, value)
+        @registry[key] = value
+      end
     end
   end
 end

spec/producer/core/env_spec.rb

@@ -17,6 +17,10 @@ module Producer::Core
         expect(env.target).not_to be
       end
 
+      it 'assigns an empty registry' do
+        expect(env.registry).to be_empty
+      end
+
       context 'when input is given as argument' do
         let(:input)   { double 'input' }
         subject(:env) { described_class.new(input: input) }
@@ -62,5 +66,20 @@ module Producer::Core
         expect(env.remote).to be env.remote
       end
     end
+
+    describe '#[]' do
+      subject(:env) { Env.new(registry: { some_key: :some_value }) }
+
+      it 'returns the value indexed by given key from the registry' do
+        expect(env[:some_key]).to eq :some_value
+      end
+    end
+
+    describe '#[]=' do
+      it 'registers given value at given index in the registry' do
+        env[:some_key] = :some_value
+        expect(env[:some_key]).to eq :some_value
+      end
+    end
   end
 end