Add a rackup option for a one-liner rack app server

lib/rack/builder.rb

@@ -37,15 +37,19 @@ def self.parse_file(config, opts = Server::Options.new)
           options = opts.parse! $1.split(/\s+/)
         end
         cfgfile.sub!(/^__END__\n.*\Z/m, '')
-        app = eval "Rack::Builder.new {\n" + cfgfile + "\n}.to_app",
-          TOPLEVEL_BINDING, config, 0
+        app = new_from_string cfgfile, config
       else
         require config
         app = Object.const_get(::File.basename(config, '.rb').capitalize)
       end
       return app, options
     end
 
+    def self.new_from_string(builder_script, file="(rackup)")
+      eval "Rack::Builder.new {\n" + builder_script + "\n}.to_app",
+        TOPLEVEL_BINDING, file, 0
+    end
+
     def initialize(default_app = nil,&block)
       @use, @map, @run = [], nil, default_app
       instance_eval(&block) if block_given?

lib/rack/server.rb

@@ -17,6 +17,10 @@ def parse!(args)
             lineno += 1
           }
 
+          opts.on("-b", "--builder BUILDER_LINE", "evaluate a BUILDER_LINE of code as a builder script") { |line|
+            options[:builder] = line
+          }
+
           opts.on("-d", "--debug", "set debugging flags (set $DEBUG to true)") {
             options[:debug] = true
           }
@@ -192,15 +196,7 @@ def default_options
     end
 
     def app
-      @app ||= begin
-        if !::File.exist? options[:config]
-          abort "configuration #{options[:config]} not found"
-        end
-
-        app, options = Rack::Builder.parse_file(self.options[:config], opt_parser)
-        self.options.merge! options
-        app
-      end
+      @app ||= options[:builder] ? build_app_from_string : build_app_and_options_from_config
     end
 
     def self.logging_middleware
@@ -273,6 +269,20 @@ def server
     end
 
     private
+      def build_app_and_options_from_config
+        if !::File.exist? options[:config]
+          abort "configuration #{options[:config]} not found"
+        end
+
+        app, options = Rack::Builder.parse_file(self.options[:config], opt_parser)
+        self.options.merge! options
+        app
+      end
+
+      def build_app_from_string
+        Rack::Builder.new_from_string(self.options[:builder])
+      end
+
       def parse_options(args)
         options = default_options
 

test/spec_builder.rb

@@ -204,4 +204,11 @@ def config_file(name)
       Rack::MockRequest.new(app).get("/").body.to_s.should.equal '1'
     end
   end
+
+  describe 'new_from_string' do
+    it "builds a rack app from string" do
+      app, = Rack::Builder.new_from_string "run lambda{|env| [200, {'Content-Type' => 'text/plane'}, ['OK']] }"
+      Rack::MockRequest.new(app).get("/").body.to_s.should.equal 'OK'
+    end
+  end
 end

test/spec_server.rb

@@ -22,6 +22,12 @@ def with_stderr
     server.app.should == "FOO"
   end
 
+  should "prefer to use :builder when it is passed in" do
+    server = Rack::Server.new(:builder => "run lambda { |env| [200, {'Content-Type' => 'text/plain'}, ['success']] }")
+    server.app.class.should == Proc
+    Rack::MockRequest.new(server.app).get("/").body.to_s.should.equal 'success'
+  end
+
   should "not include Rack::Lint in deployment or none environments" do
     server = Rack::Server.new(:app => 'foo')
     server.middleware['deployment'].flatten.should.not.include(Rack::Lint)