Avoid compiling regexs in AR::Base.respond_to?

Caches the patterns of ActiveRecord::DynamicMatchers in a class instance
variable.

activerecord/lib/active_record/dynamic_matchers.rb

@@ -35,7 +35,7 @@ def match(model, name)
         end
 
         def pattern
-          /^#{prefix}_([_a-zA-Z]\w*)#{suffix}$/
+          @pattern ||= /\A#{prefix}_([_a-zA-Z]\w*)#{suffix}\Z/
         end
 
         def prefix

activerecord/test/cases/finder_respond_to_test.rb

@@ -21,6 +21,11 @@ def test_should_respond_to_find_by_one_attribute_before_caching
     assert_respond_to Topic, :find_by_title
   end
 
+  def test_should_respond_to_find_by_with_bang
+    ensure_topic_method_is_not_cached(:find_by_title!)
+    assert_respond_to Topic, :find_by_title!
+  end
+
   def test_should_respond_to_find_by_two_attributes
     ensure_topic_method_is_not_cached(:find_by_title_and_author_name)
     assert_respond_to Topic, :find_by_title_and_author_name