Fixes the test suite in Rails 6.1

Appraisals

@@ -15,6 +15,10 @@ if RUBY_VERSION >= "2.5.0"
     gem "rails", "~> 6.0.0"
   end
 
+  appraise "rails-6-1" do
+    gem "rails", "~> 6.1.0"
+  end
+
   appraise "rails-head" do
     gem "rails", github: "rails/rails"
   end

gemfiles/rails_6_1.gemfile

@@ -0,0 +1,10 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "rake"
+gem "mocha", :require => false
+gem "appraisal"
+gem "rails", "~> 6.1.0"
+
+gemspec :path => "../"

test/jbuilder_template_test.rb

@@ -290,7 +290,7 @@ def render(*args)
 
     def render_without_parsing(source, assigns = {})
       view = build_view(fixtures: PARTIALS.merge("source.json.jbuilder" => source), assigns: assigns)
-      view.render(template: "source.json.jbuilder")
+      view.render(template: "source")
     end
 
     def build_view(options = {})