Fix tests with MySQL

Author: Nicolas Rodriguez

spec/spec_helper.rb

@@ -57,10 +57,18 @@
 
 require 'ajax-datatables-rails'
 
-ActiveRecord::Base.establish_connection(
-  adapter:  ENV.fetch('DB_ADAPTER', 'postgresql'),
-  database: 'ajax_datatables_rails'
-)
+adapter = ENV.fetch('DB_ADAPTER', 'postgresql')
+
+options = {
+  adapter:  adapter,
+  database: 'ajax_datatables_rails',
+  encoding: 'utf8'
+}
+
+options = options.merge(username: 'root', host: '127.0.0.1') if adapter == 'mysql2'
+options = options.merge(database: 'tmp/test.sqlite3') if adapter == 'sqlite3'
+
+ActiveRecord::Base.establish_connection(options)
 
 AjaxDatatablesRails.configure do |c|
   c.db_adapter = ActiveRecord::Base.connection.adapter_name.downcase.to_sym