Improve pidfile reporting and test coverage

 * Output reduced to a single line
 * Integration test added that also suppresses and checks output

lib/rack/server.rb

@@ -325,14 +325,10 @@ def write_pid
 
       def check_pid!
         case pidfile_process_status
-        when :running
-          STDERR.puts "The process is still alive. aborting."
-          exit(1)
-        when :not_owned
-          STDERR.puts "The process is still alive. And owned by another user aborting."
+        when :running, :not_owned
+          $stderr.puts "A server is already running. Check #{options[:pid]}."
           exit(1)
         when :dead
-          STDERR.puts "The process is no longer running. Removing the pid file."
           ::File.delete(options[:pid])
         end
       end
@@ -341,7 +337,6 @@ def pidfile_process_status
         return :exited unless ::File.exist?(options[:pid])
 
         pid = ::File.read(options[:pid]).to_i
-        STDERR.puts "There is already a pid file wrote a by process with pid #{pid}"
         Process.kill(0, pid)
         :running
       rescue Errno::ESRCH

test/spec_server.rb

@@ -10,6 +10,13 @@ def app
     lambda { |env| [200, {'Content-Type' => 'text/plain'}, ['success']] }
   end
 
+  def with_stderr
+    old, $stderr = $stderr, StringIO.new
+    yield $stderr
+  ensure
+    $stderr = old
+  end
+
   it "overrides :config if :app is passed in" do
     server = Rack::Server.new(:app => "FOO")
     server.app.should == "FOO"
@@ -97,4 +104,18 @@ def app
     server.send(:pidfile_process_status).should.eql :not_owned
   end
 
+  should "inform the user about existing pidfiles with running processes" do
+    pidfile = Tempfile.open('pidfile') { |f| f.write(1); break f }.path
+    server = Rack::Server.new(:pid => pidfile)
+    with_stderr do |err|
+      should.raise(SystemExit) do
+        server.start
+      end
+      err.rewind
+      output = err.read
+      output.should.match(/already running/)
+      output.should.include? pidfile
+    end
+  end
+
 end