Fixed #26813 -- Prevented empty choice in ModelChoiceField with RadioSelect for fields with blank=False.

tests/model_forms/test_modelchoicefield.py

@@ -139,6 +139,26 @@ class ModelChoiceFieldTests(TestCase):
         Category.objects.all().delete()
         self.assertIs(bool(f.choices), True)
 
+    def test_choices_radio_blank(self):
+        choices = [
+            (self.c1.pk, 'Entertainment'),
+            (self.c2.pk, 'A test'),
+            (self.c3.pk, 'Third'),
+        ]
+        categories = Category.objects.all()
+        for widget in [forms.RadioSelect, forms.RadioSelect()]:
+            for blank in [True, False]:
+                with self.subTest(widget=widget, blank=blank):
+                    f = forms.ModelChoiceField(
+                        categories,
+                        widget=widget,
+                        blank=blank,
+                    )
+                    self.assertEqual(
+                        list(f.choices),
+                        [('', '---------')] + choices if blank else choices,
+                    )
+
     def test_deepcopies_widget(self):
         class ModelChoiceForm(forms.Form):
             category = forms.ModelChoiceField(Category.objects.all())