Fix the mailer generator for rails 5

Author: Sam Phippen

lib/generators/rspec/mailer/templates/mailer_spec.rb

@@ -1,10 +1,10 @@
 require "rails_helper"
 
 <% module_namespacing do -%>
-RSpec.describe <%= class_name %>, <%= type_metatag(:mailer) %> do
+RSpec.describe <%= class_name %><%= Rails.version.to_f >= 5.0 ? "Mailer" : "" %>, <%= type_metatag(:mailer) %> do
 <% for action in actions -%>
   describe "<%= action %>" do
-    let(:mail) { <%= class_name %>.<%= action %> }
+    let(:mail) { <%= class_name %><%= Rails.version.to_f >= 5.0 ? "Mailer" : "" %>.<%= action %> }
 
     it "renders the headers" do
       expect(mail.subject).to eq(<%= action.to_s.humanize.inspect %>)

spec/generators/rspec/mailer/mailer_generator_spec.rb

@@ -13,7 +13,12 @@
       end
       it { is_expected.to exist }
       it { is_expected.to contain(/require "rails_helper"/) }
-      it { is_expected.to contain(/^RSpec.describe Posts, #{type_metatag(:mailer)}/) }
+      if Rails.version.to_f >= 5.0
+        # Rails 5 automatically appends Mailer to the provided constant so we do too
+        it { is_expected.to contain(/^RSpec.describe PostsMailer, #{type_metatag(:mailer)}/) }
+      else
+        it { is_expected.to contain(/^RSpec.describe Posts, #{type_metatag(:mailer)}/) }
+      end
       it { is_expected.to contain(/describe "index" do/) }
       it { is_expected.to contain(/describe "show" do/) }
     end