missing_presence_validation: ignore type columns for required polymorphic belongs_to associations

lib/active_record_doctor/detectors/missing_presence_validation.rb

@@ -81,7 +81,8 @@ def presence_validator_present?(model, column)
         allowed_attributes = [column.name.to_sym]
 
         belongs_to = model.reflect_on_all_associations(:belongs_to).find do |reflection|
-          reflection.foreign_key == column.name
+          reflection.foreign_key == column.name ||
+            (reflection.polymorphic? && reflection.foreign_type == column.name)
         end
         allowed_attributes << belongs_to.name.to_sym if belongs_to
 

test/active_record_doctor/detectors/missing_presence_validation_test.rb

@@ -42,6 +42,17 @@ def test_non_null_column_is_not_reported_if_association_validation_present
     refute_problems
   end
 
+  def test_non_null_type_column_is_not_reported_if_association_validation_present
+    Context.create_table(:comments) do |t|
+      t.integer :commentable_id, null: false
+      t.string :commentable_type, null: false
+    end.define_model do
+      belongs_to :commentable, polymorphic: true, required: true
+    end
+
+    refute_problems
+  end
+
   def test_not_null_column_is_not_reported_if_habtm_association
     Context.create_table(:users).define_model do
       has_and_belongs_to_many :projects, class_name: "Context::Project"