Fixed #30076 -- Added Model.get_FOO_display() even if field's choices are empty.

tests/model_fields/tests.py

@@ -1,12 +1,14 @@
 import pickle
 
 from django import forms
+from django.core.exceptions import ValidationError
 from django.db import models
 from django.test import SimpleTestCase, TestCase
 from django.utils.functional import lazy
 
 from .models import (
-    Bar, Foo, RenamedField, VerboseNameField, Whiz, WhizIter, WhizIterEmpty,
+    Bar, Choiceful, Foo, RenamedField, VerboseNameField, Whiz, WhizDelayed,
+    WhizIter, WhizIterEmpty,
 )
 
 
@@ -103,6 +105,51 @@ class BasicFieldTests(SimpleTestCase):
 
 class ChoicesTests(SimpleTestCase):
 
+    @classmethod
+    def setUpClass(cls):
+        super().setUpClass()
+        cls.no_choices = Choiceful._meta.get_field('no_choices')
+        cls.empty_choices = Choiceful._meta.get_field('empty_choices')
+        cls.empty_choices_bool = Choiceful._meta.get_field('empty_choices_bool')
+        cls.empty_choices_text = Choiceful._meta.get_field('empty_choices_text')
+        cls.with_choices = Choiceful._meta.get_field('with_choices')
+
+    def test_choices(self):
+        self.assertIsNone(self.no_choices.choices)
+        self.assertEqual(self.empty_choices.choices, ())
+        self.assertEqual(self.with_choices.choices, [(1, 'A')])
+
+    def test_flatchoices(self):
+        self.assertEqual(self.no_choices.flatchoices, [])
+        self.assertEqual(self.empty_choices.flatchoices, [])
+        self.assertEqual(self.with_choices.flatchoices, [(1, 'A')])
+
+    def test_check(self):
+        self.assertEqual(Choiceful.check(), [])
+
+    def test_invalid_choice(self):
+        model_instance = None  # Actual model instance not needed.
+        self.no_choices.validate(0, model_instance)
+        msg = "['Value 99 is not a valid choice.']"
+        with self.assertRaisesMessage(ValidationError, msg):
+            self.empty_choices.validate(99, model_instance)
+        with self.assertRaisesMessage(ValidationError, msg):
+            self.with_choices.validate(99, model_instance)
+
+    def test_formfield(self):
+        no_choices_formfield = self.no_choices.formfield()
+        self.assertIsInstance(no_choices_formfield, forms.IntegerField)
+        fields = (
+            self.empty_choices, self.with_choices, self.empty_choices_bool,
+            self.empty_choices_text,
+        )
+        for field in fields:
+            with self.subTest(field=field):
+                self.assertIsInstance(field.formfield(), forms.ChoiceField)
+
+
+class GetFieldDisplayTests(SimpleTestCase):
+
     def test_choices_and_field_display(self):
         """
         get_choices() interacts with get_FIELD_display() to return the expected
@@ -113,6 +160,7 @@ class ChoicesTests(SimpleTestCase):
         self.assertEqual(Whiz(c=9).get_c_display(), 9)          # Invalid value
         self.assertIsNone(Whiz(c=None).get_c_display())         # Blank value
         self.assertEqual(Whiz(c='').get_c_display(), '')        # Empty value
+        self.assertEqual(WhizDelayed(c=0).get_c_display(), 'Other')  # Delayed choices
 
     def test_iterator_choices(self):
         """
@@ -135,6 +183,11 @@ class ChoicesTests(SimpleTestCase):
 
 class GetChoicesTests(SimpleTestCase):
 
+    def test_empty_choices(self):
+        choices = []
+        f = models.CharField(choices=choices)
+        self.assertEqual(f.get_choices(include_blank=False), choices)
+
     def test_blank_in_choices(self):
         choices = [('', '<><>'), ('a', 'A')]
         f = models.CharField(choices=choices)