Write output from `sh' task action directly:

* Accept output as argument in Remote#execute;
* Modify ShellCommand so that env output is directly handled.

lib/producer/core/actions/shell_command.rb

@@ -3,7 +3,8 @@ module Producer
     module Actions
       class ShellCommand < Action
         def apply
-          output.puts remote.execute(arguments.first)
+          remote.execute(arguments.first, output)
+          output.puts
         end
       end
     end

lib/producer/core/remote.rb

@@ -23,8 +23,7 @@ module Producer
         @fs ||= Remote::FS.new(session.sftp.connect)
       end
 
-      def execute(command)
-        output = ''
+      def execute(command, output = '')
         channel = session.open_channel do |channel|
           channel.exec command do |ch, success|
             ch.on_data do |c, data|

lib/producer/core/testing/mock_remote.rb

@@ -6,18 +6,20 @@ module Producer
           raise 'no session for mock remote!'
         end
 
-        def execute(command)
+        def execute(command, output = '')
           tokens = command.split
           program = tokens.shift
 
           case program
           when 'echo'
-            tokens.join ' '
+            output << tokens.join(' ')
           when 'true'
-            ''
+            output << ''
           when 'false'
             raise RemoteCommandExecutionError
           end
+
+          output
         end
       end
     end

spec/producer/core/remote_spec.rb

@@ -79,6 +79,7 @@ module Producer::Core
     describe '#execute', :ssh do
       let(:arguments) { 'some remote command' }
       let(:command)   { "echo #{arguments}" }
+      let(:output)    { StringIO.new }
 
       it 'executes the given command in a new channel' do
         story_with_new_channel do |ch|
@@ -88,7 +89,7 @@ module Producer::Core
         expect_story_completed { remote.execute command }
       end
 
-      it 'returns the output' do
+      it 'returns the command standard output output' do
         story_with_new_channel do |ch|
           ch.sends_exec command
           ch.gets_data arguments
@@ -96,6 +97,15 @@ module Producer::Core
         expect(remote.execute command).to eq arguments
       end
 
+      it 'writes command standard output to provided output' do
+        story_with_new_channel do |ch|
+          ch.sends_exec command
+          ch.gets_data arguments
+        end
+        remote.execute command, output
+        expect(output.string).to eq arguments
+      end
+
       it 'raises an exception when the exit status code is not 0' do
         story_with_new_channel do |ch|
           ch.sends_exec command

spec/support/test_env_helpers.rb

@@ -15,7 +15,9 @@ module TestEnvHelpers
 
   def expect_execution(command)
     opts = { expected_from: caller.first }
-    RSpec::Mocks.expect_message(env.remote, :execute, opts).with(command)
+    RSpec::Mocks
+      .expect_message(env.remote, :execute, opts)
+      .with(command, env.output)
   end