Add test case for `collection_singular_ids` with symbol primary keys

This is a regression test for #27864.

2 files changed, 9 insertions, 1 deletions

diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index 046020e310..7c9c9e81ab 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -869,6 +869,14 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     assert_equal [dev], company.developers
   end
 
+  def test_collection_singular_ids_setter_with_required_type_cast
+    company = companies(:rails_core)
+    dev = Developer.first
+
+    company.developer_ids = [dev.id.to_s]
+    assert_equal [dev], company.developers
+  end
+
   def test_collection_singular_ids_setter_with_string_primary_keys
     assert_nothing_raised do
       book = books(:awdr)
diff --git a/activerecord/test/models/contract.rb b/activerecord/test/models/contract.rb
index 9454217e8d..f273badd85 100644
--- a/activerecord/test/models/contract.rb
+++ b/activerecord/test/models/contract.rb
@@ -2,7 +2,7 @@
 
 class Contract < ActiveRecord::Base
   belongs_to :company
-  belongs_to :developer
+  belongs_to :developer, primary_key: :id
   belongs_to :firm, foreign_key: "company_id"
 
   before_save :hi