Use an empty AttributeMethodMatcher by default.

This means that attribute methods which don't exist will get generated
when define_attribute_methods is called, so we don't have to use hacks
like `attribute_method_suffix ''`.

activemodel/lib/active_model/attribute_methods.rb

@@ -60,7 +60,7 @@ module ActiveModel
 
     included do
       class_attribute :attribute_method_matchers, :instance_writer => false
-      self.attribute_method_matchers = []
+      self.attribute_method_matchers = [ClassMethods::AttributeMethodMatcher.new]
     end
 
     module ClassMethods
@@ -357,8 +357,11 @@ module ActiveModel
           if attribute_method_matchers_cache.key?(method_name)
             attribute_method_matchers_cache[method_name]
           else
+            # Must try to match prefixes/suffixes first, or else the matcher with no prefix/suffix
+            # will match every time.
+            matchers = attribute_method_matchers.partition(&:plain?).reverse.flatten(1)
             match = nil
-            attribute_method_matchers.detect { |method| match = method.match(method_name) }
+            matchers.detect { |method| match = method.match(method_name) }
             attribute_method_matchers_cache[method_name] = match
           end
         end
@@ -387,6 +390,10 @@ module ActiveModel
           def method_name(attr_name)
             @method_name % attr_name
           end
+
+          def plain?
+            prefix.empty? && suffix.empty?
+          end
         end
     end
 

activemodel/test/cases/attribute_methods_test.rb

@@ -24,7 +24,16 @@ end
 class ModelWithAttributes2
   include ActiveModel::AttributeMethods
 
+  attr_accessor :attributes
+
   attribute_method_suffix '_test'
+
+private
+  def attribute(name)
+    attributes[name.to_s]
+  end
+
+  alias attribute_test attribute
 end
 
 class ModelWithAttributesWithSpaces
@@ -129,4 +138,12 @@ class AttributeMethodsTest < ActiveModel::TestCase
     assert !ModelWithAttributes.new.respond_to?(:foo)
     assert_raises(NoMethodError) { ModelWithAttributes.new.foo }
   end
+
+  test 'acessing a suffixed attribute' do
+    m = ModelWithAttributes2.new
+    m.attributes = { 'foo' => 'bar' }
+
+    assert_equal 'bar', m.foo
+    assert_equal 'bar', m.foo_test
+  end
 end