4 files changed, 92 insertions, 5 deletions
diff --git a/actionmailer/CHANGELOG b/actionmailer/CHANGELOG
index c7fadfed39..b4122e7072 100644
--- a/actionmailer/CHANGELOG
+++ b/actionmailer/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Introduce a new base test class for testing Mailers.  ActionMailer::TestCase [Koz]
+
 * Fix silent failure of rxml templates.  #9879 [jstewart]
 
 
diff --git a/actionmailer/lib/action_mailer/test_case.rb b/actionmailer/lib/action_mailer/test_case.rb
new file mode 100644
index 0000000000..5d0ddddce9
--- /dev/null
+++ b/actionmailer/lib/action_mailer/test_case.rb
@@ -0,0 +1,59 @@
+require 'active_support/test_case'
+
+module ActionMailer
+  class NonInferrableMailerError < ::StandardError
+    def initialize(name)
+      super "Unable to determine the mailer to test from #{name}. " +
+        "You'll need to specify it using tests YourMailer in your " +
+        "test case definition"
+    end
+  end
+  # New Test Super class for forward compatibility.
+  # To override
+  class TestCase < ActiveSupport::TestCase
+    include ActionMailer::Quoting
+
+    class << self
+      def tests(mailer)
+        write_inheritable_attribute(:mailer_class, mailer)
+      end
+
+      def mailer_class
+        if mailer = read_inheritable_attribute(:mailer_class)
+          mailer
+        else
+          tests determine_default_mailer(name)
+        end
+      end
+
+      def determine_default_mailer(name)
+        name.sub(/Test$/, '').constantize
+      rescue NameError => e
+        raise NonInferrableMailerError.new(name)
+      end
+    end
+
+    def setup
+      ActionMailer::Base.delivery_method = :test
+      ActionMailer::Base.perform_deliveries = true
+      ActionMailer::Base.deliveries = []
+
+      @expected = TMail::Mail.new
+      @expected.set_content_type "text", "plain", { "charset" => charset }
+      @expected.mime_version = '1.0'
+    end
+
+    private
+      def charset
+        "utf-8"
+      end
+
+      def encode(subject)
+        quoted_printable(subject, charset)
+      end
+
+      def read_fixture(action)
+        IO.readlines(File.join(RAILS_ROOT, 'test', 'fixtures', mailer_class.name.underscore, action))
+      end
+  end
+end
diff --git a/actionmailer/test/abstract_unit.rb b/actionmailer/test/abstract_unit.rb
index 649e7982cc..0a73b1b462 100644
--- a/actionmailer/test/abstract_unit.rb
+++ b/actionmailer/test/abstract_unit.rb
@@ -2,6 +2,7 @@ require 'test/unit'
 
 $:.unshift "#{File.dirname(__FILE__)}/../lib"
 require 'action_mailer'
+require 'action_mailer/test_case'
 
 # Show backtraces for deprecated behavior for quicker cleanup.
 ActiveSupport::Deprecation.debug = true
diff --git a/actionmailer/test/test_helper_test.rb b/actionmailer/test/test_helper_test.rb
index 08f92865ca..eb17e3e803 100644
--- a/actionmailer/test/test_helper_test.rb
+++ b/actionmailer/test/test_helper_test.rb
@@ -8,13 +8,38 @@ class TestHelperMailer < ActionMailer::Base
   end
 end
 
-class TestHelperTest < Test::Unit::TestCase
-  def setup
-    ActionMailer::Base.delivery_method = :test
-    ActionMailer::Base.perform_deliveries = true
-    ActionMailer::Base.deliveries = []
+class TestHelperMailerTest < ActionMailer::TestCase
+
+  def test_setup_sets_right_action_mailer_options
+    assert_equal :test, ActionMailer::Base.delivery_method
+    assert ActionMailer::Base.perform_deliveries
+    assert_equal [], ActionMailer::Base.deliveries
+  end
+
+  def test_setup_creates_the_expected_mailer
+    assert @expected.is_a?(TMail::Mail)
+    assert_equal "1.0", @expected.mime_version
+    assert_equal "text/plain", @expected.content_type
+  end
+
+  def test_mailer_class_is_correctly_inferred
+    assert_equal TestHelperMailer, self.class.mailer_class
+  end
+
+  def test_determine_default_mailer_raises_correct_error
+    assert_raises(ActionMailer::NonInferrableMailerError) do
+      self.class.determine_default_mailer("NotAMailerTest")
+    end
   end
   
+  def test_charset_is_utf_8
+    assert_equal "utf-8", charset
+  end
+
+  def test_encode
+    assert_equal "=?utf-8?Q?=0aasdf=0a?=", encode("\nasdf\n")
+  end
+
   def test_assert_emails
     assert_nothing_raised do
       assert_emails 1 do