Support mailer methods with default/optional arguments; Support matching email methods that accept parameters when no specific arguments are expected.

Author: Joel Lubrano

lib/rspec/rails/matchers/have_enqueued_mail.rb

@@ -9,6 +9,8 @@ module Matchers
       #
       # @see RSpec::Rails::Matchers#have_enqueued_mail
       class HaveEnqueuedMail < RSpec::Matchers::BuiltIn::BaseMatcher
+        include RSpec::Mocks::ExampleMethods
+
         def initialize(mailer_class, method_name)
           @mailer_class = mailer_class
           @method_name = method_name
@@ -71,7 +73,21 @@ def expected_count_message
         end
 
         def mailer_args
-          [@mailer_class.name, @method_name.to_s, 'deliver_now'] + @args
+          base_args = [@mailer_class.name, @method_name.to_s, 'deliver_now']
+
+          if @args.any?
+            base_args + @args
+          else
+            mailer_method_arity = @mailer_class.instance_method(@method_name).arity
+
+            number_of_args = if mailer_method_arity.negative?
+                               (mailer_method_arity + 1).abs
+                             else
+                               mailer_method_arity
+                             end
+
+            base_args + Array.new(number_of_args) { anything }
+          end
         end
 
         def check_active_job_adapter

spec/rspec/rails/matchers/have_enqueued_mail_spec.rb

@@ -8,6 +8,7 @@
   class TestMailer < ActionMailer::Base
     def test_email; end
     def email_with_args(arg1, arg2); end
+    def email_with_optional_args(required_arg, optional_arg = nil); end
   end
 end
 
@@ -110,6 +111,20 @@ def email_with_args(arg1, arg2); end
       }.to have_enqueued_mail(TestMailer, :email_with_args)
     end
 
+    it "passes for mailer methods with default arguments" do
+      expect {
+        TestMailer.email_with_optional_args('required').deliver_later
+      }.to have_enqueued_mail(TestMailer, :email_with_optional_args)
+
+      expect {
+        TestMailer.email_with_optional_args('required').deliver_later
+      }.to have_enqueued_mail(TestMailer, :email_with_optional_args).with('required')
+
+      expect {
+        TestMailer.email_with_optional_args('required', 'optional').deliver_later
+      }.to have_enqueued_mail(TestMailer, :email_with_optional_args).with('required', 'optional')
+    end
+
     it "passes with provided argument matchers" do
       expect {
         TestMailer.email_with_args(1, 2).deliver_later