Raise on create for singular association when parent is unpersisted

A collection association will raise on `#create_association` when the parent is
unpersisted. A singular association should do the same. This addresses
issue #29219.

1 files changed, 9 insertions, 0 deletions

diff --git a/activerecord/test/cases/associations/has_one_associations_test.rb b/activerecord/test/cases/associations/has_one_associations_test.rb
index 7c11d2e7fc..bf3b8dcd63 100644
--- a/activerecord/test/cases/associations/has_one_associations_test.rb
+++ b/activerecord/test/cases/associations/has_one_associations_test.rb
@@ -307,6 +307,15 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
     end
   end
 
+  def test_create_when_parent_is_new_raises
+    firm = Firm.new
+    error = assert_raise(ActiveRecord::RecordNotSaved) do
+      firm.create_account
+    end
+
+    assert_equal "You cannot call create unless the parent is saved", error.message
+  end
+
   def test_reload_association
     odegy = companies(:odegy)