Use instances rather than class methods

Rather than sending Griddler.configuration.processor_method to
Griddler.configuration.processor_class with a Griddler::Email as an
argument (i.e., EmailProcessor.process(email)), instantiate
Griddler.configuration.processor_class with a Griddler::Email and call
Griddler.configuration.processor_method on that object (i.e.,
EmailProcessor.new(email).process).

This encourages the behavior of separating logic into methods within an
EmailProcessor, which is better than having a single class method with
many responsibilities or passing state around between class methods.

NEWS.md

@@ -1,5 +1,9 @@
 ## 1.0.0
 
+* Use instances of email processor classes rather than calling class methods.
+  https://github.com/thoughtbot/griddler/pull/153
+
+  *Caleb Thompson*
 * Remove configuration of email addresses for to, from, and cc.
   https://github.com/thoughtbot/griddler/pull/150
 

app/controllers/griddler/emails_controller.rb

@@ -9,13 +9,17 @@ def create
 
   private
 
+  delegate :processor_class, :processor_method, :email_service, to: :griddler_configuration
+
   def normalized_params
-    Array.wrap(Griddler.configuration.email_service.normalize_params(params))
+    Array.wrap(email_service.normalize_params(params))
   end
 
   def process_email(email)
-    processor_class  = Griddler.configuration.processor_class
-    processor_method = Griddler.configuration.processor_method
-    processor_class.public_send(processor_method, email)
+    processor_class.new(email).public_send(processor_method)
+  end
+
+  def griddler_configuration
+    Griddler.configuration
   end
 end

spec/controllers/griddler/emails_controller_spec.rb

@@ -24,21 +24,21 @@
     end
 
     it 'calls process on the custom processor class' do
-      my_handler = double
-      my_handler.should_receive(:process)
+      my_handler = double(process: nil)
+      my_handler.should_receive(:new).and_return(my_handler)
       Griddler.configuration.stub(processor_class: my_handler)
 
       post :create, email_params
     end
 
     it 'calls the custom processor method on the processor class' do
       Griddler.configuration.stub(processor_method: :perform)
-      griddler_email = double
-      Griddler::Email.should_receive(:new).and_return(griddler_email)
+      fake_processor = double(perform: nil)
 
-      EmailProcessor.should_receive(:perform).with(griddler_email)
+      EmailProcessor.should_receive(:new).and_return(fake_processor)
+      fake_processor.should_receive(:perform)
 
-      post :create, to: '[email protected]'
+      post :create, email_params
     end
   end
 

spec/dummy/app/models/email_processor.rb

@@ -1,6 +1,7 @@
 class EmailProcessor
-  cattr_accessor :email
-  def self.process(email)
-    @@email = email
+  def initialize(email)
+    @email = email
   end
+
+  def process; end
 end