refactor test by using let instead of before block when creating instance variables

spec/models/aspect_membership_spec.rb

@@ -7,25 +7,25 @@ require 'spec_helper'
 describe AspectMembership, :type => :model do
 
   describe '#before_destroy' do
-    before do
-      @aspect = alice.aspects.create(:name => "two")
-      @contact = alice.contact_for(bob.person)
+    let(:aspect) { alice.aspects.create(:name => "two") }
+    let(:contact) { alice.contact_for(bob.person) }
+    let(:am) { alice.aspects.where(:name => "generic").first.aspect_memberships.first }
 
-      @am = alice.aspects.where(:name => "generic").first.aspect_memberships.first
-      allow(@am).to receive(:user).and_return(alice)
+    before do
+      allow(am).to receive(:user).and_return(alice)
     end
 
     it 'calls disconnect if its the last aspect for the contact' do
-      expect(alice).to receive(:disconnect).with(@contact)
+      expect(alice).to receive(:disconnect).with(contact)
 
-      @am.destroy
+      am.destroy
     end
 
     it 'does not call disconnect if its not the last aspect for the contact' do
       expect(alice).not_to receive(:disconnect)
 
-      alice.add_contact_to_aspect(@contact, @aspect)
-      @am.destroy     
+      alice.add_contact_to_aspect(contact, aspect)
+      am.destroy
     end
   end