require abstract_mysql_adapter if it exists

Gemfile

@@ -16,11 +16,11 @@ group :development do
     gem "dm-migrations",      "1.0.0"
     gem "dm-sqlite-adapter",  "1.0.0"
   gem "mongoid"
-    gem "tzinfo"             
+    gem "tzinfo"
     gem "mongo_ext"
     gem "bson_ext"
-  gem "mongo_mapper"         
-  gem "couch_potato"         
+  gem "mongo_mapper"
+  gem "couch_potato"
   gem "sequel",               "~>3.21.0"
   #gem "ibm_db"  # I don't want to add this dependency, even as a dev one since it requires DB2 to be installed
   gem 'mysql'

lib/database_cleaner/active_record/truncation.rb

@@ -1,5 +1,12 @@
 require 'active_record/base'
+
 require 'active_record/connection_adapters/abstract_adapter'
+
+begin
+  require 'active_record/connection_adapters/abstract_mysql_adapter'
+rescue LoadError
+end
+
 require "database_cleaner/generic/truncation"
 require 'database_cleaner/active_record/base'
 

spec/database_cleaner/configuration_spec.rb

@@ -17,7 +17,7 @@ describe ::DatabaseCleaner do
 
   context "orm specification" do
     it "should not accept unrecognised orms" do
-      expect { ::DatabaseCleaner[nil] }.should raise_error(::DatabaseCleaner::NoORMDetected)
+      expect { ::DatabaseCleaner[nil] }.to raise_error(::DatabaseCleaner::NoORMDetected)
     end
 
     it "should accept :active_record" do