Try to slightly optimize EmailHeleprs

spec/support/email_helpers.rb

 module EmailHelpers
-  def sent_to_user?(user)
-    ActionMailer::Base.deliveries.flat_map(&:to).count(user.email) == 1
+  def sent_to_user?(user, recipients = nil)
+    recipients ||= ActionMailer::Base.deliveries.flat_map(&:to)
+
+    recipients.count(user.email) == 1
   end
 
   def reset_delivered_emails!
@@ -8,17 +10,19 @@ def reset_delivered_emails!
   end
 
   def should_only_email(*users)
-    users.each {|user| should_email(user) }
     recipients = ActionMailer::Base.deliveries.flat_map(&:to)
+
+    users.each { |user| should_email(user, recipients) }
+
     expect(recipients.count).to eq(users.count)
   end
 
-  def should_email(user)
-    expect(sent_to_user?(user)).to be_truthy
+  def should_email(user, recipients = nil)
+    expect(sent_to_user?(user, recipients)).to be_truthy
   end
 
-  def should_not_email(user)
-    expect(sent_to_user?(user)).to be_falsey
+  def should_not_email(user, recipients = nil)
+    expect(sent_to_user?(user, recipients)).to be_falsey
   end
 
   def should_email_no_one