assert_emails in block form use the given number as expected value

[y-yagi]

In assert_equal calling in assert_email, appoint the value that added original count and number to. However, appoint only number in error message.

Therefore, when call deliver_now before calling assert_equal, output is different from Expected in error message.

test "notifier mail" do
  NotifierMailer.welcome.deliver_now
  assert_emails 2 do
    NotifierMailer.welcome.deliver_now
  end
end

  1) Failure:
NotifierMailerTest#test_notifier_mail [/home/yaginuma/program/rails/master/test/mailers/notifier_mailer_test.rb:6]:
2 emails expected, but 1 were sent.
Expected: 3
  Actual: 2

This patch fixes the argument of assert_equal, so it's output as follows.

  1) Failure:
NotifierMailerTest#test_notifier_mail [/home/yaginuma/program/rails/master/test/mailers/notifier_mailer_test.rb:6]:
2 emails expected, but 1 were sent.
Expected: 2
  Actual: 1

[senny]

@y-yagi thank you 💛

[y-yagi]

@senny Thanks!