Inject include Clearance::User inside model body (#677)

* Inject `include Clearance::User` inside model body

Clearance generator was inserting `include Clearance::User` between
`class User <` and `ActiveRecord::Base`, which is not correct.

Our spec was not checking if the generator was including clearance
user model correctly or not. Let's add the test to ensure the generator
is inserting the content properly. This commit fixes #676.

* Add versionize app templates for test helpers

lib/generators/clearance/install/install_generator.rb

@@ -24,7 +24,7 @@ def create_or_inject_clearance_into_user_model
           inject_into_file(
             "app/models/user.rb",
             "  include Clearance::User\n\n",
-            after: "class User < ",
+            after: "class User < #{models_inherit_from}\n",
           )
         else
           @inherit_from = models_inherit_from

spec/app_templates/app/models/rails5/user.rb

@@ -0,0 +1,5 @@
+class User < ApplicationRecord
+  def previously_existed?
+    true
+  end
+end

spec/generators/clearance/install/install_generator_spec.rb

@@ -37,8 +37,8 @@
 
         expect(user_class).to exist
         expect(user_class).to have_correct_syntax
+        expect(user_class).to contain_models_inherit_from
         expect(user_class).to contain("include Clearance::User")
-        expect(user_class).to contain proper_model_superclass
       end
     end
 
@@ -52,6 +52,7 @@
 
         expect(user_class).to exist
         expect(user_class).to have_correct_syntax
+        expect(user_class).to contain_models_inherit_from
         expect(user_class).to contain("include Clearance::User")
         expect(user_class).to have_method("previously_existed?")
       end
@@ -129,7 +130,11 @@ def table_does_not_exist(name)
     end
   end
 
-  def proper_model_superclass
+  def contain_models_inherit_from
+    contain "< #{models_inherit_from}\n"
+  end
+
+  def models_inherit_from
     if Rails.version >= "5.0.0"
       "ApplicationRecord"
     else

spec/support/generator_spec_helpers.rb

@@ -18,7 +18,7 @@ def provide_existing_application_controller
   end
 
   def provide_existing_user_class
-    copy_to_generator_root("app/models", "user.rb")
+    copy_to_generator_root("app/models", versionize_template("user.rb"))
     allow(File).to receive(:exist?).and_call_original
     allow(File).to receive(:exist?).with("app/models/user.rb").and_return(true)
   end
@@ -32,6 +32,14 @@ def copy_to_generator_root(destination, template)
     FileUtils.mkdir_p(destination)
     FileUtils.cp(template_file, destination)
   end
+
+  def versionize_template(template_file)
+    if Rails.version >= "5.0.0"
+      template_file = ["rails5", template_file].join("/")
+    end
+
+    template_file
+  end
 end
 
 RSpec.configure do |config|