ActionMailer::TestCase::Behavior Ruby on Rails 5.1.2 Module ActionMailer::TestCase::Behavior actionmailer/lib/action_mailer/test_case.rb Namespace MODULE ActionMailer::TestCase::Behavior::ClassMethods Included Modules ActiveSupport::Testing::ConstantLookup ActionMailer::TestHelper Rails::Dom::Testing::Assertions::SelectorAssertions Rails::Dom::Testing::Assertions::DomAssertions