Add support for Rails 6 (Sorcery#238)

* Cache bundler on Travis

* Add support for Rails 6

Since the usage of `MigrationContext` was changed in rails/rails#36439,
adds a branch to MigrationHelper.

We are loading 'rails/all' in our test code, it implicitly load action_text from Rails 6.
ActionText requires ApplicationController, adds it.
ref: https://github.com/rails/rails/blob/v6.0.3/actiontext/lib/action_text/engine.rb#L50

* Exclude Ruby 2.4 for Rails 6

Rails 6 does't support Ruby 2.4.
ref: rails/rails#34754

.travis.yml

@@ -1,9 +1,17 @@
 language: ruby
+cache: bundler
+
 rvm:
   - 2.4.9
   - 2.5.7
   - 2.6.5
   - 2.7.1
 
 gemfile:
-  - Gemfile
+  - gemfiles/rails_52.gemfile
+  - gemfiles/rails_60.gemfile
+
+jobs:
+  exclude:
+  - rvm: 2.4.9
+    gemfile: gemfiles/rails_60.gemfile

Gemfile

@@ -1,8 +1,8 @@
 source 'https://rubygems.org'
 
 gem 'pry'
-gem 'rails', '~> 5.2.0'
+gem 'rails'
 gem 'rails-controller-testing'
-gem 'sqlite3', '~> 1.3.6'
+gem 'sqlite3'
 
 gemspec

gemfiles/rails_52.gemfile

@@ -0,0 +1,7 @@
+source 'https://rubygems.org'
+
+gem 'rails', '~> 5.2.0'
+gem 'rails-controller-testing'
+gem 'sqlite3', '~> 1.3.6'
+
+gemspec path: '..'

gemfiles/rails_60.gemfile

@@ -0,0 +1,7 @@
+source 'https://rubygems.org'
+
+gem 'rails', '~> 6.0.0'
+gem 'rails-controller-testing'
+gem 'sqlite3', '~> 1.4'
+
+gemspec path: '..'

spec/rails_app/app/controllers/application_controller.rb

@@ -0,0 +1,2 @@
+class ApplicationController < ActionController::Base
+end

spec/rails_app/app/controllers/sorcery_controller.rb

@@ -1,6 +1,6 @@
 require 'oauth'
 
-class SorceryController < ActionController::Base
+class SorceryController < ApplicationController
   protect_from_forgery
 
   before_action :require_login_from_http_basic, only: [:test_http_basic_auth]

spec/support/migration_helper.rb

@@ -1,19 +1,29 @@
 class MigrationHelper
   class << self
     def migrate(path)
-      if ActiveRecord.version >= Gem::Version.new('5.2.0')
+      if ActiveRecord.version >= Gem::Version.new('6.0.0')
+        ActiveRecord::MigrationContext.new(path, schema_migration).migrate
+      elsif ActiveRecord.version >= Gem::Version.new('5.2.0')
         ActiveRecord::MigrationContext.new(path).migrate
       else
         ActiveRecord::Migrator.migrate(path)
       end
     end
 
     def rollback(path)
-      if ActiveRecord.version >= Gem::Version.new('5.2.0')
+      if ActiveRecord.version >= Gem::Version.new('6.0.0')
+        ActiveRecord::MigrationContext.new(path, schema_migration).rollback
+      elsif ActiveRecord.version >= Gem::Version.new('5.2.0')
         ActiveRecord::MigrationContext.new(path).rollback
       else
         ActiveRecord::Migrator.rollback(path)
       end
     end
+
+    private
+
+    def schema_migration
+      ActiveRecord::Base.connection.schema_migration
+    end
   end
 end