Print a warning when in dry run mode

features/cli_dry_run.feature

@@ -1,11 +1,17 @@
 Feature: CLI dry run option
 
-  Scenario: perfoms a trial run without applying actions
+  Background:
     Given a recipe with:
       """
       task :say_hello do
         echo 'hello'
       end
       """
+
+  Scenario: perfoms a trial run without applying actions
     When I successfully execute the recipe with option -n
     Then the output must not contain "hello"
+
+  Scenario: prints a warning before any output
+    When I successfully execute the recipe with option -n
+    Then the output must match /\AWarning: running in dry run mode, actions will NOT be applied/

lib/producer/core/env.rb

@@ -27,14 +27,14 @@ module Producer
       def logger
         @logger ||= begin
           logger = Logger.new(output)
-          logger.level = verbose? ? Logger::INFO : Logger::ERROR
+          logger.level = verbose? ? Logger::INFO : Logger::WARN
           logger.formatter = LoggerFormatter.new
           logger
         end
       end
 
-      def log(message)
+      def log(message, severity = :info)
-        logger.info message
+        logger.send severity, message
       end
 
       def verbose?

lib/producer/core/logger_formatter.rb

@@ -2,7 +2,14 @@ module Producer
   module Core
     class LoggerFormatter < Logger::Formatter
       def call(severity, datetime, progname, message)
-        message + "\n"
+        prefix(severity) + message + "\n"
+      end
+
+
+      private
+
+      def prefix(severity)
+        severity == 'WARN' ? 'Warning: ' : ''
       end
     end
   end

lib/producer/core/worker.rb

@@ -1,6 +1,9 @@
 module Producer
   module Core
     class Worker
+      DRY_RUN_WARNING =
+        'running in dry run mode, actions will NOT be applied'.freeze
+
       attr_accessor :env
 
       def initialize(env)
@@ -8,6 +11,8 @@ module Producer
       end
 
       def process(tasks)
+        env.log DRY_RUN_WARNING, :warn if env.dry_run?
+
         tasks.each { |t| process_task t }
       end
 

spec/producer/core/env_spec.rb

@@ -113,8 +113,8 @@ module Producer::Core
         expect(output.string).to include 'some message'
       end
 
-      it 'has a log level of ERROR' do
+      it 'has a log level of WARN' do
-        expect(env.logger.level).to eq Logger::ERROR
+        expect(env.logger.level).to eq Logger::WARN
       end
 
       it 'uses our formatter' do
@@ -135,6 +135,13 @@ module Producer::Core
         expect(env.logger).to receive(:info).with 'message'
         env.log 'message'
       end
+
+      context 'when second argument is :warn' do
+        it 'logs a warning message through the assigned logger' do
+          expect(env.logger).to receive(:warn).with 'message'
+          env.log 'message', :warn
+        end
+      end
     end
 
     describe '#verbose?' do

spec/producer/core/logger_formatter_spec.rb

@@ -13,6 +13,14 @@ module Producer::Core
       it 'returns the given message with a line separator' do
         expect(subject).to eq "#{message}\n"
       end
+
+      context 'when severity is WARN' do
+        let(:severity) { 'WARN' }
+
+        it 'prefix the message with `Warning:\'' do
+          expect(subject).to match /\AWarning: #{message}/
+        end
+      end
     end
   end
 end

spec/producer/core/worker_spec.rb

@@ -10,6 +10,18 @@ module Producer::Core
         expect(worker).to receive(:process_task).with(:some_task)
         worker.process [:some_task]
       end
+
+      context 'when dry run is enabled' do
+        before { allow(env).to receive(:dry_run?) { true } }
+
+        it 'warns dry run is enabled' do
+          expect(env).to receive(:log).with(
+            /\Arunning in dry run mode, actions will NOT be applied\z/,
+            :warn
+          )
+          worker.process []
+        end
+      end
     end
 
     describe '#process_task' do