Slightly refactor presence matcher

...in preparation for detecting models that support the full Attributes
API more closely.

lib/shoulda/matchers/active_model/validate_presence_of_matcher.rb

@@ -234,7 +234,7 @@ def disallows_original_or_typecast_value?(value)
         end
 
         def disallowed_values
-          if collection?
+          if collection_association?
             [Array.new]
           else
             values = []
@@ -251,16 +251,6 @@ def disallowed_values
           end
         end
 
-        def collection?
-          if association_reflection
-            [:has_many, :has_and_belongs_to_many].include?(
-              association_reflection.macro,
-            )
-          else
-            false
-          end
-        end
-
         def should_add_footnote_about_belongs_to?
           belongs_to_association_being_validated? &&
             presence_validation_exists_on_attribute?
@@ -316,18 +306,27 @@ def belongs_to_association_configured_to_be_required?
         end
 
         def belongs_to_association_being_validated?
-          !!association_reflection &&
-            association_reflection.macro == :belongs_to
+          association? && association_reflection.macro == :belongs_to
         end
 
         def attribute_accepts_string_values?
-          !association_reflection && (
+          !association? && (
             !attribute_type.respond_to?(:coder) ||
             !attribute_type.coder ||
             attribute_type.coder.object_class == String
           )
         end
 
+        def association?
+          association_reflection.present?
+        end
+
+        def collection_association?
+          association? && association_reflection.macro.in?(
+            [:has_many, :has_and_belongs_to_many],
+          )
+        end
+
         def association_name
           association_reflection.name
         end
@@ -337,16 +336,11 @@ def association_options
         end
 
         def association_reflection
-          model.respond_to?(:reflect_on_association) &&
-            model.reflect_on_association(@attribute)
+          model.try(:reflect_on_association, @attribute)
         end
 
         def attribute_type
-          if model.respond_to?(:attribute_types)
-            model.attribute_types[@attribute.to_s]
-          else
-            LegacyAttributeType.new(model, @attribute)
-          end
+          RailsShim.attribute_type_for(model, @attribute)
         end
 
         def presence_validation_exists_on_attribute?
@@ -356,25 +350,6 @@ def presence_validation_exists_on_attribute?
         def model
           @subject.class
         end
-
-        class LegacyAttributeType
-          def initialize(model, attribute_name)
-            @model = model
-            @attribute_name = attribute_name
-          end
-
-          def coder
-            if model.respond_to?(:serialized_attributes)
-              ActiveSupport::Deprecation.silence do
-                model.serialized_attributes[attribute_name.to_s]
-              end
-            end
-          end
-
-          private
-
-          attr_reader :model, :attribute_name
-        end
       end
     end
   end

lib/shoulda/matchers/rails_shim.rb

@@ -156,6 +156,14 @@ def secure_password_module
           nil
         end
 
+        def attribute_type_for(model, attribute_name)
+          if model.respond_to?(:attribute_types)
+            model.attribute_types[attribute_name.to_s]
+          else
+            LegacyAttributeType.new(model, attribute_name)
+          end
+        end
+
         private
 
         def simply_generate_validation_message(
@@ -179,6 +187,25 @@ def simply_generate_validation_message(
             { default: default_translation_keys }.merge(options)
           I18n.translate(primary_translation_key, translate_options)
         end
+
+        class LegacyAttributeType
+          def initialize(model, attribute_name)
+            @model = model
+            @attribute_name = attribute_name
+          end
+
+          def coder
+            if model.respond_to?(:serialized_attributes)
+              ActiveSupport::Deprecation.silence do
+                model.serialized_attributes[attribute_name.to_s]
+              end
+            end
+          end
+
+          private
+
+          attr_reader :model, :attribute_name
+        end
       end
     end
   end