[1.11.x] Refs #28192 -- Fixed documentation of ChoiceField choices requirement

Thanks Tim Graham for noticing the issue.
Backport of 54caca2d34 from master.

tests/forms_tests/field_tests/test_choicefield.py

@@ -55,6 +55,10 @@ class ChoiceFieldTest(FormFieldAssertionsMixin, SimpleTestCase):
         with self.assertRaisesMessage(ValidationError, msg):
             f.clean('6')
 
+    def test_choicefield_choices_default(self):
+        f = ChoiceField()
+        self.assertEqual(f.choices, [])
+
     def test_choicefield_callable(self):
         def choices():
             return [('J', 'John'), ('P', 'Paul')]