Ensure user input option is valid

app.rb

@@ -1,3 +1,22 @@
 #!/usr/bin/ruby
 
-# Entry point
+require_relative './lib/handle_input'
+
+command = HandleInput.new
+
+$stdout.print "Would you like to LIST available products, SHOP, VIEW basket, EXIT without placing an order? \n"
+
+# Read user input
+loop do
+  input = gets.chomp
+
+  next if input.empty?
+
+  unless 'EXIT'.match?(input)
+    command.interpret(input)
+    next
+  end
+
+  $stdout.print "Goodbye! \n"
+  break
+end

lib/handle_input.rb

@@ -0,0 +1,16 @@
+require_relative 'item'
+
+# HandleInput class
+class HandleInput
+  # Actions
+  ACTIONS = %w[LIST SHOP VIEW EXIT].freeze
+
+  # Interpret method
+  # @param command [String]
+  # @return
+  def interpret(command)
+    return unless ACTIONS.include?(command)
+
+    $stdout.print "#{command} \n"
+  end
+end

lib/watermelon.rb

@@ -11,11 +11,14 @@ def initialize(name)
     @pack = nil
   end
 
-  def pack_size(selection)
-    return unless OPTIONS.include?(selection)
-
-    return @pack = Pack.new(3, Money.new(699, 'NZD')) if selection == 3
-    @pack = Pack.new(5, Money.new(899, 'NZD')) if selection == 5
+  # Pack size method
+  # @Param qty [Int]
+  # @Return @pack
+  def pack_size(qty)
+    return unless OPTIONS.include?(qty)
+
+    return @pack = Pack.new(3, Money.new(699, 'NZD')) if qty == 3
+    @pack = Pack.new(5, Money.new(899, 'NZD')) if qty == 5
   end
 end
 

spec/handle_input_spec.rb

@@ -0,0 +1,13 @@
+require 'rspec'
+require 'spec_helper'
+require './lib/handle_input'
+
+describe HandleInput do
+  describe '#interpret' do
+    it 'should return nil unless command matches a value in ACTIONS array' do
+      instance = HandleInput.new
+
+      expect(instance.interpret('hello')).to be_nil
+    end
+  end
+end