Test against rails 5.2.0.rc to get early feedback without causing TravisCI build failures

.travis.yml

@@ -11,11 +11,17 @@ before_install:
   - gem install bundler
 
 gemfile:
+  - gemfiles/rails_5_2.gemfile
   - gemfiles/rails_5_1.gemfile
   - gemfiles/rails_5_0.gemfile
   - gemfiles/rails_4_2.gemfile
   - gemfiles/dalli2.gemfile
 
+matrix:
+  allow_failures:
+    - gemfile: gemfiles/rails_5_2.gemfile
+  fast_finish: true
+
 services:
   - redis
   - memcached

Appraisals

@@ -1,3 +1,8 @@
+appraise 'rails_5-2' do
+  gem 'activesupport', '~> 5.2.0.a'
+  gem 'actionpack', '~> 5.2.0.a'
+end
+
 appraise 'rails_5-1' do
   gem 'activesupport', '~> 5.1.0'
   gem 'actionpack', '~> 5.1.0'

gemfiles/rails_5_2.gemfile

@@ -0,0 +1,14 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "activesupport", "~> 5.2.0.a"
+gem "actionpack", "~> 5.2.0.a"
+
+group :development do
+  gem "pry"
+  gem "guard"
+  gem "guard-minitest"
+end
+
+gemspec path: "../"