Implement `echo' task action

features/actions/echo.feature

@@ -0,0 +1,12 @@
+Feature: `echo' task action
+
+  Scenario: ouputs text
+    Given a recipe with:
+      """
+      task :some_task do
+        echo 'hello'
+      end
+      """
+    When I execute the recipe
+    Then the exit status must be 0
+    And the output must contain exactly "hello\n"

lib/producer/core.rb

@@ -1,4 +1,5 @@
 require 'producer/core/action'
+require 'producer/core/actions/echo'
 require 'producer/core/actions/shell_command'
 require 'producer/core/cli'
 require 'producer/core/env'

lib/producer/core/actions/echo.rb

@@ -0,0 +1,11 @@
+module Producer
+  module Core
+    module Actions
+      class Echo < Action
+        def apply
+          env.output arguments.first
+        end
+      end
+    end
+  end
+end

lib/producer/core/task/dsl.rb

@@ -10,6 +10,7 @@ module Producer
           end
         end
 
+        define_action :echo,  Actions::Echo
         define_action :sh,    Actions::ShellCommand
 
         attr_accessor :actions

spec/producer/core/actions/echo_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+module Producer::Core
+  describe Actions::Echo do
+    let(:env)       { Env.new }
+    let(:text)      { 'hello' }
+    subject(:echo)  { Actions::Echo.new(env, text) }
+
+    describe '#apply' do
+      before do
+        env.output = StringIO.new
+      end
+
+      it 'outputs the string given as argument through env.output' do
+        expect(env).to receive(:output).with(text)
+        echo.apply
+      end
+    end
+  end
+end
+

spec/producer/core/task/dsl_spec.rb

@@ -6,7 +6,7 @@ module Producer::Core
     let(:env)     { double('env') }
     subject(:dsl) { Task::DSL.new &block }
 
-    %w[sh].each do |action|
+    %w[echo sh].each do |action|
       it "has `#{action}' action defined" do
         expect(dsl).to respond_to action.to_sym
       end