bring back single process starting

lib/foreman/cli.rb

@@ -10,7 +10,7 @@ class Foreman::CLI < Thor
 
   class_option :procfile, :type => :string, :aliases => "-f", :desc => "Default: Procfile"
 
-  desc "start", "Start the application"
+  desc "start [PROCESS]", "Start the application (or a specific PROCESS)"
 
   class_option :procfile, :type => :string, :aliases => "-f", :desc => "Default: Procfile"
   class_option :app_root, :type => :string, :aliases => "-d", :desc => "Default: Procfile directory"
@@ -27,8 +27,9 @@ class Foreman::CLI < Thor
     end
   end
 
-  def start
+  def start(process=nil)
     check_procfile!
+    engine.options[:concurrency] = "#{process}=1" if process
     engine.start
   end
 

lib/foreman/engine.rb

@@ -23,7 +23,7 @@ class Foreman::Engine
   def initialize(procfile, options={})
     @procfile  = Foreman::Procfile.new(procfile)
     @directory = options[:app_root] || File.expand_path(File.dirname(procfile))
-    @options = options
+    @options = options.dup
     @environment = read_environment_files(options[:env])
     @output_mutex = Mutex.new
   end

spec/foreman/cli_spec.rb

@@ -3,6 +3,8 @@ require "foreman/cli"
 
 describe "Foreman::CLI", :fakefs do
   subject { Foreman::CLI.new }
+  let(:engine) { subject.send(:engine) }
+  let(:entries) { engine.procfile.entries.inject({}) { |h,e| h.update(e.name => e) } }
 
   describe "start" do
     describe "with a non-existent Procfile" do
@@ -22,6 +24,15 @@ describe "Foreman::CLI", :fakefs do
         mock.instance_of(Foreman::Engine).start
         subject.start
       end
+
+      it "can run a single process" do
+        dont_allow(subject).error
+        stub(engine).watch_for_output
+        stub(engine).watch_for_termination
+        mock(entries["alpha"]).spawn(1, is_a(IO), engine.directory, {}, 5000) { [] }
+        mock(entries["bravo"]).spawn(0, is_a(IO), engine.directory, {}, 5100) { [] }
+        subject.start("alpha")
+      end
     end
   end