Simplify actions specs

spec/producer/core/actions/echo_spec.rb

@@ -2,15 +2,11 @@ require 'spec_helper'
 
 module Producer::Core
   describe Actions::Echo do
-    let(:env)       { Env.new }
+    let(:env)       { double 'env' }
     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

spec/producer/core/actions/shell_command_spec.rb

@@ -8,9 +8,7 @@ module Producer::Core
     subject(:sh)        { Actions::ShellCommand.new(env, command) }
 
     describe '#apply' do
-      before do
-        env.output = StringIO.new
-      end
+      before { env.output = StringIO.new }
 
       it 'delegates the call to env.remote.execute method' do
         expect(env.remote).to receive(:execute).with(command)