Fix deprecation warning on Rails 6.0

Gemfile

@@ -7,3 +7,4 @@ gemspec
 gem 'rails'
 gem 'rspec-rails', '>= 3.2.0'
 gem 'sqlite3'
+gem 'rails-controller-testing'

lib/faml/rails_handler.rb

@@ -1,12 +1,13 @@
 # frozen_string_literal: true
 module Faml
   class RailsHandler
-    def call(template)
+    def call(template, source = nil)
+      source ||= template.source
       Engine.new(
         use_html_safe: true,
         generator: Temple::Generators::RailsOutputBuffer,
         filename: template.identifier,
-      ).call(template.source)
+      ).call(source)
     end
   end
 end

spec/rails/app/assets/config/manifest.js

@@ -0,0 +1,3 @@
+//= link_tree ../images
+//= link_directory ../javascripts .js
+//= link_directory ../stylesheets .css

spec/rails/spec/requests/faml_spec.rb

@@ -61,7 +61,7 @@
     end
 
     it 'works with id' do
-      get '/books/object_ref', id: 123
+      get '/books/object_ref', params: { id: 123 }
       expect(response).to be_ok
       expect(response.body).to include("<div class='book' id='book_123'>")
     end