Implement recipe evaluation feature

features/recipe.feature

@@ -0,0 +1,10 @@
+Feature: recipe evaluation
+
+  Scenario: evaluates ruby code in a recipe
+    Given a recipe with:
+      """
+      puts 'hello from recipe'
+      """
+    When I execute the recipe
+    Then the exit status must be 0
+    And the output must contain "hello from recipe"

features/steps/recipe_steps.rb

@@ -0,0 +1,7 @@
+Given(/^a recipe with:$/) do |recipe_body|
+  write_file 'recipe.rb', recipe_body
+end
+
+When(/^I execute the recipe$/) do
+  run_simple('producer localhost recipe.rb', false)
+end

lib/producer/core.rb

@@ -2,6 +2,7 @@ require 'producer/core/version'
 
 module Producer
   module Core
-    autoload :CLI, 'producer/core/cli'
+    autoload :CLI,    'producer/core/cli'
+    autoload :Recipe, 'producer/core/recipe'
   end
 end

lib/producer/core/cli.rb

@@ -12,6 +12,8 @@ module Producer
 
       def run!
         print_usage_and_exit(64) unless @arguments.length == 2
+
+        Recipe.from_file(@arguments[1]).evaluate
       end
 
 

lib/producer/core/recipe.rb

@@ -0,0 +1,19 @@
+module Producer
+  module Core
+    class Recipe
+      attr_reader :code
+
+      def self.from_file(filepath)
+        new(File.read(filepath))
+      end
+
+      def initialize(code)
+        @code = code
+      end
+
+      def evaluate
+        Object.new.instance_eval @code
+      end
+    end
+  end
+end

spec/fixtures/recipes/empty.rb

@@ -0,0 +1 @@
+# can contain tasks written in ruby language.

spec/producer/core/cli_spec.rb

@@ -2,7 +2,9 @@ require 'spec_helper'
 
 module Producer::Core
   describe CLI do
-    let(:arguments) { %w{host recipe.rb} }
+    include FixturesHelpers
+
+    let(:arguments) { ['host', fixture_path_for('recipes/empty.rb')] }
     subject(:cli)   { CLI.new(arguments) }
 
     describe '#initialize' do
@@ -12,6 +14,18 @@ module Producer::Core
     end
 
     describe '#run!' do
+      it 'builds a recipe' do
+        expect(Recipe).to receive(:from_file).with(arguments[1]).and_call_original
+        cli.run!
+      end
+
+      it 'evaluates the recipe' do
+        recipe = double('recipe')
+        allow(Recipe).to receive(:from_file).and_return(recipe)
+        expect(recipe).to receive(:evaluate)
+        cli.run!
+      end
+
       context 'missing argument' do
         let(:arguments) { %w{host} }
         let(:stdout)    { StringIO.new }

spec/producer/core/recipe_spec.rb

@@ -0,0 +1,39 @@
+require 'spec_helper'
+
+module Producer::Core
+  describe Recipe do
+    include FixturesHelpers
+
+    let(:code)        { 'some ruby code' }
+    subject(:recipe)  { Recipe.new(code) }
+
+    describe '.from_file' do
+      it 'builds a recipe whose code is read from given file path' do
+        filepath = fixture_path_for 'recipes/empty.rb'
+        recipe = Recipe.from_file(filepath)
+        expect(recipe.code).to eq File.read(filepath)
+      end
+    end
+
+    describe '#initialize' do
+      it 'builds a recipe' do
+        expect(recipe).to be_a Recipe
+      end
+    end
+
+    describe '#code' do
+      it 'returns the assigned code' do
+        expect(recipe.code).to eq code
+      end
+    end
+
+    describe '#evaluate' do
+      let(:message) { 'error from recipe' }
+      let(:code)    { "raise '#{message}'" }
+
+      it 'evaluates its code' do
+        expect { recipe.evaluate }.to raise_error(RuntimeError, 'error from recipe')
+      end
+    end
+  end
+end