lib/rack/app/test.rb in rack-app-3.2.1 vs lib/rack/app/test.rb in rack-app-3.3.0

@@ -23,12 +23,18 @@
 
     end
   end
 
   def rack_app(&block)
-    app_class = defined?(__rack_app_class__) ? __rack_app_class__ : nil
-    constructors = []
-    constructors << __rack_app_constructor__ if defined?(__rack_app_constructor__) and __rack_app_constructor__.is_a?(Proc)
-    Rack::App::Test::Utils.rack_app_by(app_class, constructors, &block)
+
+    @app ||= lambda do
+      app_class = defined?(__rack_app_class__) ? __rack_app_class__ : nil
+      constructors = []
+      constructors << __rack_app_constructor__ if defined?(__rack_app_constructor__) and __rack_app_constructor__.is_a?(Proc)
+      Rack::App::Test::Utils.rack_app_by(app_class, constructors)
+    end.call
+
+    block.is_a?(Proc) ? @app.instance_exec(&block) : @app
+
   end
 
 end
\ No newline at end of file