Associations now raise `ArgumentError` on name conflicts.

Dangerous association names conflicts include instance or class
methods already defined by `ActiveRecord::Base`.

3 files changed, 30 insertions, 0 deletions

diff --git a/activerecord/test/cases/associations/belongs_to_associations_test.rb b/activerecord/test/cases/associations/belongs_to_associations_test.rb
index 2283ba66db..9340bc0a83 100644
--- a/activerecord/test/cases/associations/belongs_to_associations_test.rb
+++ b/activerecord/test/cases/associations/belongs_to_associations_test.rb
@@ -853,4 +853,14 @@ class BelongsToAssociationsTest < ActiveRecord::TestCase
     assert post.save
     assert_equal post.author_id, author2.id
   end
+
+  test 'dangerous association name raises ArgumentError' do
+    [:errors, 'errors', :save, 'save'].each do |name|
+      assert_raises(ArgumentError, "Association #{name} should not be allowed") do
+        Class.new(ActiveRecord::Base) do
+          belongs_to name
+        end
+      end
+    end
+  end
 end
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index cf1e50890e..a86fb15719 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -1820,4 +1820,14 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
       topic.approved_replies.create!
     end
   end
+
+  test 'dangerous association name raises ArgumentError' do
+    [:errors, 'errors', :save, 'save'].each do |name|
+      assert_raises(ArgumentError, "Association #{name} should not be allowed") do
+        Class.new(ActiveRecord::Base) do
+          has_many name
+        end
+      end
+    end
+  end
 end
diff --git a/activerecord/test/cases/associations/has_one_associations_test.rb b/activerecord/test/cases/associations/has_one_associations_test.rb
index d4edef03d6..a4650ccdf2 100644
--- a/activerecord/test/cases/associations/has_one_associations_test.rb
+++ b/activerecord/test/cases/associations/has_one_associations_test.rb
@@ -564,4 +564,14 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
       end
     end
   end
+
+  test 'dangerous association name raises ArgumentError' do
+    [:errors, 'errors', :save, 'save'].each do |name|
+      assert_raises(ArgumentError, "Association #{name} should not be allowed") do
+        Class.new(ActiveRecord::Base) do
+          has_one name
+        end
+      end
+    end
+  end
 end