Fix has_and_belongs_to_many in a namespaced model pointing to a non namespaced model

Now the following case will work fine

    class Tag < ActiveRecord::Base
    end

    class Publisher::Article < ActiveRecord::Base
      has_and_belongs_to_many :tags
    end

Fixes #15761

1 files changed, 9 insertions, 0 deletions

diff --git a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
index 080c499444..3f8b26980f 100644
--- a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
@@ -869,6 +869,15 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     assert_includes magazine.articles, article
   end
 
+  def test_has_and_belongs_to_many_in_a_namespaced_model_pointing_to_a_non_namespaced_model
+    article = Publisher::Article.create
+    tag = Tag.create
+    article.tags << tag
+    article.save
+
+    assert_includes article.tags, tag
+  end
+
   def test_redefine_habtm
     child = SubDeveloper.new("name" => "Aredridel")
     child.special_projects << SpecialProject.new("name" => "Special Project")