Refs #26813 -- Added test for ModelChoiceField.choices when using RadioSelect widget.

tests/model_forms/tests.py

@@ -259,6 +259,20 @@ class ModelFormBaseTest(TestCase):
         award = form.save()
         self.assertIsNone(award.character)
 
+    def test_blank_foreign_key_with_radio(self):
+        class BookForm(forms.ModelForm):
+            class Meta:
+                model = Book
+                fields = ['author']
+                widgets = {'author': forms.RadioSelect()}
+
+        writer = Writer.objects.create(name='Joe Doe')
+        form = BookForm()
+        self.assertEqual(list(form.fields['author'].choices), [
+            ('', '---------'),
+            (writer.pk, 'Joe Doe'),
+        ])
+
     def test_save_blank_false_with_required_false(self):
         """
         A ModelForm with a model with a field set to blank=False and the form