Improve small details in specs:

* Fix coding standards;
* Simplify some expectations (eq instead of be matcher);
* Expect identity on block instead of calling;
* Change some before call as oneliners;
* Avoid shadowing variable names;
* Improve wording where needed.

spec/producer/core/interpreter_spec.rb

@@ -12,24 +12,22 @@ module Producer::Core
     end
 
     describe '#process_task' do
-      let(:action)  { double('action') }
+      let(:action)  { double 'action' }
       let(:task)    { double('task', actions: [action]).as_null_object }
 
       context 'when task condition is met' do
         it 'applies the actions' do
-          expect(action).to receive(:apply)
-          interpreter.process_task(task)
+          expect(action).to receive :apply
+          interpreter.process_task task
         end
       end
 
       context 'when task condition is not met' do
-        before do
-          allow(task).to receive(:condition_met?) { false }
-        end
+        before { allow(task).to receive(:condition_met?) { false } }
 
         it 'does not apply the actions' do
-          expect(action).not_to receive(:apply)
-          interpreter.process_task(task)
+          expect(action).not_to receive :apply
+          interpreter.process_task task
         end
       end
     end