deprecate loading adapters from database_cleaner core gem.

lib/database_cleaner/base.rb

@@ -159,14 +159,22 @@ module DatabaseCleaner
     end
 
     def orm_strategy(strategy)
-      require "database_cleaner/#{orm.to_s}/#{strategy.to_s}"
       orm_module.const_get(strategy.to_s.capitalize)
-    rescue LoadError
-      if orm_module.respond_to? :available_strategies
-        raise UnknownStrategySpecified, "The '#{strategy}' strategy does not exist for the #{orm} ORM!  Available strategies: #{orm_module.available_strategies.join(', ')}"
-      else
-        raise UnknownStrategySpecified, "The '#{strategy}' strategy does not exist for the #{orm} ORM!"
+    rescue NameError
+      $stderr.puts <<-TEXT
+        Requiring the `database_cleaner` gem directly is deprecated, and will raise an error in database_cleaner 2.0. Instead, please require the specific gem (or gems) for your ORM.
+        For example, replace `gem "database_cleaner"` with `gem "database_cleaner-active_record"` in your Gemfile. See ### for more information.
+      TEXT
+      begin
+        require "database_cleaner/#{orm.to_s}/#{strategy.to_s}"
+      rescue LoadError
+        if orm_module.respond_to?(:available_strategies)
+          raise UnknownStrategySpecified, "The '#{strategy}' strategy does not exist for the #{orm} ORM!  Available strategies: #{orm_module.available_strategies.join(', ')}"
+        else
+          raise UnknownStrategySpecified, "The '#{strategy}' strategy does not exist for the #{orm} ORM!"
+        end
       end
+      retry
     end
 
     def autodetect

spec/database_cleaner/base_spec.rb

@@ -314,7 +314,6 @@ module DatabaseCleaner
 
       it "loads and instantiates the described strategy" do
         stub_const "DatabaseCleaner::ActiveRecord::Cunningplan", strategy_class
-        expect(subject).to receive(:require).with("database_cleaner/active_record/cunningplan")
 
         subject.strategy = :cunningplan
         expect(subject.strategy).to be_a strategy_class