Register mailer tests for minitest's spec DSL

actionmailer/lib/action_mailer/test_case.rb

@@ -10,6 +10,13 @@ module ActionMailer
   end
 
   class TestCase < ActiveSupport::TestCase
+
+    # Use AM::TestCase for the base class when describing a mailer
+    register_spec_type(self) do |desc|
+      Class === desc && desc < ActionMailer::Base
+    end
+    register_spec_type(/Mailer( ?Test)?\z/i, self)
+
     module Behavior
       extend ActiveSupport::Concern
 

actionmailer/test/spec_type_test.rb

@@ -0,0 +1,37 @@
+require 'abstract_unit'
+
+class NotificationMailer < ActionMailer::Base; end
+class Notifications < ActionMailer::Base; end
+
+class SpecTypeTest < ActiveSupport::TestCase
+  def assert_mailer actual
+    assert_equal ActionMailer::TestCase, actual
+  end
+
+  def refute_mailer actual
+    refute_equal ActionMailer::TestCase, actual
+  end
+
+  def test_spec_type_resolves_for_class_constants
+    assert_mailer MiniTest::Spec.spec_type(NotificationMailer)
+    assert_mailer MiniTest::Spec.spec_type(Notifications)
+  end
+
+  def test_spec_type_resolves_for_matching_strings
+    assert_mailer MiniTest::Spec.spec_type("WidgetMailer")
+    assert_mailer MiniTest::Spec.spec_type("WidgetMailerTest")
+    assert_mailer MiniTest::Spec.spec_type("Widget Mailer Test")
+    # And is not case sensitive
+    assert_mailer MiniTest::Spec.spec_type("widgetmailer")
+    assert_mailer MiniTest::Spec.spec_type("widgetmailertest")
+    assert_mailer MiniTest::Spec.spec_type("widget mailer test")
+  end
+
+  def test_spec_type_wont_match_non_space_characters
+    refute_mailer MiniTest::Spec.spec_type("Widget Mailer\tTest")
+    refute_mailer MiniTest::Spec.spec_type("Widget Mailer\rTest")
+    refute_mailer MiniTest::Spec.spec_type("Widget Mailer\nTest")
+    refute_mailer MiniTest::Spec.spec_type("Widget Mailer\fTest")
+    refute_mailer MiniTest::Spec.spec_type("Widget MailerXTest")
+  end
+end