django/tests/invalid_models_tests/test_ordinary_fields.py

import unittest
import uuid

from django.core.checks import Error
from django.core.checks import Warning as DjangoWarning
from django.db import connection, models
from django.db.models.functions import Coalesce, Pi
from django.test import SimpleTestCase, TestCase, skipIfDBFeature, skipUnlessDBFeature
from django.test.utils import isolate_apps, override_settings
from django.utils.functional import lazy
from django.utils.timezone import now
from django.utils.translation import gettext_lazy as _
from django.utils.version import get_docs_version


@isolate_apps("invalid_models_tests")
class AutoFieldTests(SimpleTestCase):
    def test_valid_case(self):
        class Model(models.Model):
            id = models.AutoField(primary_key=True)

        field = Model._meta.get_field("id")
        self.assertEqual(field.check(), [])

    def test_primary_key(self):
        # primary_key must be True. Refs #12467.
        class Model(models.Model):
            field = models.AutoField(primary_key=False)

            # Prevent Django from autocreating `id` AutoField, which would
            # result in an error, because a model must have exactly one
            # AutoField.
            another = models.IntegerField(primary_key=True)

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "AutoFields must set primary_key=True.",
                    obj=field,
                    id="fields.E100",
                ),
            ],
        )

    def test_max_length_warning(self):
        class Model(models.Model):
            auto = models.AutoField(primary_key=True, max_length=2)

        field = Model._meta.get_field("auto")
        self.assertEqual(
            field.check(),
            [
                DjangoWarning(
                    "'max_length' is ignored when used with %s."
                    % field.__class__.__name__,
                    hint="Remove 'max_length' from field",
                    obj=field,
                    id="fields.W122",
                ),
            ],
        )


@isolate_apps("invalid_models_tests")
class BinaryFieldTests(SimpleTestCase):
    def test_valid_default_value(self):
        class Model(models.Model):
            field1 = models.BinaryField(default=b"test")
            field2 = models.BinaryField(default=None)

        for field_name in ("field1", "field2"):
            field = Model._meta.get_field(field_name)
            self.assertEqual(field.check(), [])

    def test_str_default_value(self):
        class Model(models.Model):
            field = models.BinaryField(default="test")

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "BinaryField's default cannot be a string. Use bytes content "
                    "instead.",
                    obj=field,
                    id="fields.E170",
                ),
            ],
        )


@isolate_apps("invalid_models_tests")
class CharFieldTests(TestCase):
    def test_valid_field(self):
        class Model(models.Model):
            field = models.CharField(
                max_length=255,
                choices=[
                    ("1", "item1"),
                    ("2", "item2"),
                ],
                db_index=True,
            )

        field = Model._meta.get_field("field")
        self.assertEqual(field.check(), [])

    def test_missing_max_length(self):
        class Model(models.Model):
            field = models.CharField()

        field = Model._meta.get_field("field")
        expected = (
            []
            if connection.features.supports_unlimited_charfield
            else [
                Error(
                    "CharFields must define a 'max_length' attribute.",
                    obj=field,
                    id="fields.E120",
                ),
            ]
        )
        self.assertEqual(field.check(), expected)

    def test_negative_max_length(self):
        class Model(models.Model):
            field = models.CharField(max_length=-1)

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'max_length' must be a positive integer.",
                    obj=field,
                    id="fields.E121",
                ),
            ],
        )

    def test_bad_max_length_value(self):
        class Model(models.Model):
            field = models.CharField(max_length="bad")

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'max_length' must be a positive integer.",
                    obj=field,
                    id="fields.E121",
                ),
            ],
        )

    def test_str_max_length_value(self):
        class Model(models.Model):
            field = models.CharField(max_length="20")

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'max_length' must be a positive integer.",
                    obj=field,
                    id="fields.E121",
                ),
            ],
        )

    def test_str_max_length_type(self):
        class Model(models.Model):
            field = models.CharField(max_length=True)

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'max_length' must be a positive integer.",
                    obj=field,
                    id="fields.E121",
                ),
            ],
        )

    def test_non_iterable_choices(self):
        class Model(models.Model):
            field = models.CharField(max_length=10, choices="bad")

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'choices' must be an iterable (e.g., a list or tuple).",
                    obj=field,
                    id="fields.E004",
                ),
            ],
        )

    def test_non_iterable_choices_two_letters(self):
        """Two letters isn't a valid choice pair."""

        class Model(models.Model):
            field = models.CharField(max_length=10, choices=["ab"])

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'choices' must be an iterable containing (actual value, "
                    "human readable name) tuples.",
                    obj=field,
                    id="fields.E005",
                ),
            ],
        )

    def test_iterable_of_iterable_choices(self):
        class ThingItem:
            def __init__(self, value, display):
                self.value = value
                self.display = display

            def __iter__(self):
                return iter((self.value, self.display))

            def __len__(self):
                return 2

        class Things:
            def __iter__(self):
                return iter((ThingItem(1, 2), ThingItem(3, 4)))

        class ThingWithIterableChoices(models.Model):
            thing = models.CharField(max_length=100, blank=True, choices=Things())

        self.assertEqual(ThingWithIterableChoices._meta.get_field("thing").check(), [])

    def test_choices_containing_non_pairs(self):
        class Model(models.Model):
            field = models.CharField(max_length=10, choices=[(1, 2, 3), (1, 2, 3)])

        class Model2(models.Model):
            field = models.IntegerField(choices=[0])

        for model in (Model, Model2):
            with self.subTest(model.__name__):
                field = model._meta.get_field("field")
                self.assertEqual(
                    field.check(),
                    [
                        Error(
                            "'choices' must be an iterable containing (actual "
                            "value, human readable name) tuples.",
                            obj=field,
                            id="fields.E005",
                        ),
                    ],
                )

    def test_choices_containing_lazy(self):
        class Model(models.Model):
            field = models.CharField(
                max_length=10, choices=[["1", _("1")], ["2", _("2")]]
            )

        self.assertEqual(Model._meta.get_field("field").check(), [])

    def test_lazy_choices(self):
        class Model(models.Model):
            field = models.CharField(
                max_length=10, choices=lazy(lambda: [[1, "1"], [2, "2"]], tuple)()
            )

        self.assertEqual(Model._meta.get_field("field").check(), [])

    def test_choices_named_group(self):
        class Model(models.Model):
            field = models.CharField(
                max_length=10,
                choices=[
                    ["knights", [["L", "Lancelot"], ["G", "Galahad"]]],
                    ["wizards", [["T", "Tim the Enchanter"]]],
                    ["R", "Random character"],
                ],
            )

        self.assertEqual(Model._meta.get_field("field").check(), [])

    def test_choices_named_group_non_pairs(self):
        class Model(models.Model):
            field = models.CharField(
                max_length=10,
                choices=[["knights", [["L", "Lancelot", "Du Lac"]]]],
            )

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'choices' must be an iterable containing (actual value, "
                    "human readable name) tuples.",
                    obj=field,
                    id="fields.E005",
                ),
            ],
        )

    def test_choices_named_group_bad_structure(self):
        class Model(models.Model):
            field = models.CharField(
                max_length=10,
                choices=[
                    [
                        "knights",
                        [
                            ["Noble", [["G", "Galahad"]]],
                            ["Combative", [["L", "Lancelot"]]],
                        ],
                    ],
                ],
            )

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'choices' must be an iterable containing (actual value, "
                    "human readable name) tuples.",
                    obj=field,
                    id="fields.E005",
                ),
            ],
        )

    def test_choices_named_group_lazy(self):
        class Model(models.Model):
            field = models.CharField(
                max_length=10,
                choices=[
                    [_("knights"), [["L", _("Lancelot")], ["G", _("Galahad")]]],
                    ["R", _("Random character")],
                ],
            )

        self.assertEqual(Model._meta.get_field("field").check(), [])

    def test_choices_in_max_length(self):
        class Model(models.Model):
            field = models.CharField(
                max_length=2,
                choices=[("ABC", "Value Too Long!"), ("OK", "Good")],
            )
            group = models.CharField(
                max_length=2,
                choices=[
                    ("Nested", [("OK", "Good"), ("Longer", "Longer")]),
                    ("Grouped", [("Bad", "Bad")]),
                ],
            )

        for name, choice_max_length in (("field", 3), ("group", 6)):
            with self.subTest(name):
                field = Model._meta.get_field(name)
                self.assertEqual(
                    field.check(),
                    [
                        Error(
                            "'max_length' is too small to fit the longest value "
                            "in 'choices' (%d characters)." % choice_max_length,
                            obj=field,
                            id="fields.E009",
                        ),
                    ],
                )

    def test_bad_db_index_value(self):
        class Model(models.Model):
            field = models.CharField(max_length=10, db_index="bad")

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'db_index' must be None, True or False.",
                    obj=field,
                    id="fields.E006",
                ),
            ],
        )

    def test_bad_validators(self):
        class Model(models.Model):
            field = models.CharField(max_length=10, validators=[True])

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "All 'validators' must be callable.",
                    hint=(
                        "validators[0] (True) isn't a function or instance of a "
                        "validator class."
                    ),
                    obj=field,
                    id="fields.E008",
                ),
            ],
        )

    @unittest.skipUnless(connection.vendor == "mysql", "Test valid only for MySQL")
    def test_too_long_char_field_under_mysql(self):
        from django.db.backends.mysql.validation import DatabaseValidation

        class Model(models.Model):
            field = models.CharField(unique=True, max_length=256)

        field = Model._meta.get_field("field")
        validator = DatabaseValidation(connection=connection)
        self.assertEqual(
            validator.check_field(field),
            [
                DjangoWarning(
                    "%s may not allow unique CharFields to have a max_length > "
                    "255." % connection.display_name,
                    hint=(
                        "See: https://docs.djangoproject.com/en/%s/ref/databases/"
                        "#mysql-character-fields" % get_docs_version()
                    ),
                    obj=field,
                    id="mysql.W003",
                )
            ],
        )

    def test_db_collation(self):
        class Model(models.Model):
            field = models.CharField(max_length=100, db_collation="anything")

        field = Model._meta.get_field("field")
        error = Error(
            "%s does not support a database collation on CharFields."
            % connection.display_name,
            id="fields.E190",
            obj=field,
        )
        expected = (
            [] if connection.features.supports_collation_on_charfield else [error]
        )
        self.assertEqual(field.check(databases=self.databases), expected)

    def test_db_collation_required_db_features(self):
        class Model(models.Model):
            field = models.CharField(max_length=100, db_collation="anything")

            class Meta:
                required_db_features = {"supports_collation_on_charfield"}

        field = Model._meta.get_field("field")
        self.assertEqual(field.check(databases=self.databases), [])


@isolate_apps("invalid_models_tests")
class DateFieldTests(SimpleTestCase):
    maxDiff = None

    def test_auto_now_and_auto_now_add_raise_error(self):
        class Model(models.Model):
            field0 = models.DateTimeField(auto_now=True, auto_now_add=True, default=now)
            field1 = models.DateTimeField(
                auto_now=True, auto_now_add=False, default=now
            )
            field2 = models.DateTimeField(
                auto_now=False, auto_now_add=True, default=now
            )
            field3 = models.DateTimeField(
                auto_now=True, auto_now_add=True, default=None
            )

        expected = []
        checks = []
        for i in range(4):
            field = Model._meta.get_field("field%d" % i)
            expected.append(
                Error(
                    "The options auto_now, auto_now_add, and default "
                    "are mutually exclusive. Only one of these options "
                    "may be present.",
                    obj=field,
                    id="fields.E160",
                )
            )
            checks.extend(field.check())
            self.assertEqual(checks, expected)

    def test_fix_default_value(self):
        class Model(models.Model):
            field_dt = models.DateField(default=now())
            field_d = models.DateField(default=now().date())
            field_now = models.DateField(default=now)

        field_dt = Model._meta.get_field("field_dt")
        field_d = Model._meta.get_field("field_d")
        field_now = Model._meta.get_field("field_now")
        errors = field_dt.check()
        errors.extend(field_d.check())
        errors.extend(field_now.check())  # doesn't raise a warning
        self.assertEqual(
            errors,
            [
                DjangoWarning(
                    "Fixed default value provided.",
                    hint="It seems you set a fixed date / time / datetime "
                    "value as default for this field. This may not be "
                    "what you want. If you want to have the current date "
                    "as default, use `django.utils.timezone.now`",
                    obj=field_dt,
                    id="fields.W161",
                ),
                DjangoWarning(
                    "Fixed default value provided.",
                    hint="It seems you set a fixed date / time / datetime "
                    "value as default for this field. This may not be "
                    "what you want. If you want to have the current date "
                    "as default, use `django.utils.timezone.now`",
                    obj=field_d,
                    id="fields.W161",
                ),
            ],
        )

    @override_settings(USE_TZ=True)
    def test_fix_default_value_tz(self):
        self.test_fix_default_value()


@isolate_apps("invalid_models_tests")
class DateTimeFieldTests(SimpleTestCase):
    maxDiff = None

    def test_fix_default_value(self):
        class Model(models.Model):
            field_dt = models.DateTimeField(default=now())
            field_d = models.DateTimeField(default=now().date())
            field_now = models.DateTimeField(default=now)

        field_dt = Model._meta.get_field("field_dt")
        field_d = Model._meta.get_field("field_d")
        field_now = Model._meta.get_field("field_now")
        errors = field_dt.check()
        errors.extend(field_d.check())
        errors.extend(field_now.check())  # doesn't raise a warning
        self.assertEqual(
            errors,
            [
                DjangoWarning(
                    "Fixed default value provided.",
                    hint="It seems you set a fixed date / time / datetime "
                    "value as default for this field. This may not be "
                    "what you want. If you want to have the current date "
                    "as default, use `django.utils.timezone.now`",
                    obj=field_dt,
                    id="fields.W161",
                ),
                DjangoWarning(
                    "Fixed default value provided.",
                    hint="It seems you set a fixed date / time / datetime "
                    "value as default for this field. This may not be "
                    "what you want. If you want to have the current date "
                    "as default, use `django.utils.timezone.now`",
                    obj=field_d,
                    id="fields.W161",
                ),
            ],
        )

    @override_settings(USE_TZ=True)
    def test_fix_default_value_tz(self):
        self.test_fix_default_value()


@isolate_apps("invalid_models_tests")
class DecimalFieldTests(SimpleTestCase):
    def test_required_attributes(self):
        class Model(models.Model):
            field = models.DecimalField()

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "DecimalFields must define a 'decimal_places' attribute.",
                    obj=field,
                    id="fields.E130",
                ),
                Error(
                    "DecimalFields must define a 'max_digits' attribute.",
                    obj=field,
                    id="fields.E132",
                ),
            ],
        )

    def test_negative_max_digits_and_decimal_places(self):
        class Model(models.Model):
            field = models.DecimalField(max_digits=-1, decimal_places=-1)

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'decimal_places' must be a non-negative integer.",
                    obj=field,
                    id="fields.E131",
                ),
                Error(
                    "'max_digits' must be a positive integer.",
                    obj=field,
                    id="fields.E133",
                ),
            ],
        )

    def test_bad_values_of_max_digits_and_decimal_places(self):
        class Model(models.Model):
            field = models.DecimalField(max_digits="bad", decimal_places="bad")

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'decimal_places' must be a non-negative integer.",
                    obj=field,
                    id="fields.E131",
                ),
                Error(
                    "'max_digits' must be a positive integer.",
                    obj=field,
                    id="fields.E133",
                ),
            ],
        )

    def test_decimal_places_greater_than_max_digits(self):
        class Model(models.Model):
            field = models.DecimalField(max_digits=9, decimal_places=10)

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'max_digits' must be greater or equal to 'decimal_places'.",
                    obj=field,
                    id="fields.E134",
                ),
            ],
        )

    def test_valid_field(self):
        class Model(models.Model):
            field = models.DecimalField(max_digits=10, decimal_places=10)

        field = Model._meta.get_field("field")
        self.assertEqual(field.check(), [])


@isolate_apps("invalid_models_tests")
class FileFieldTests(SimpleTestCase):
    def test_valid_default_case(self):
        class Model(models.Model):
            field = models.FileField()

        self.assertEqual(Model._meta.get_field("field").check(), [])

    def test_valid_case(self):
        class Model(models.Model):
            field = models.FileField(upload_to="somewhere")

        field = Model._meta.get_field("field")
        self.assertEqual(field.check(), [])

    def test_primary_key(self):
        class Model(models.Model):
            field = models.FileField(primary_key=False, upload_to="somewhere")

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "'primary_key' is not a valid argument for a FileField.",
                    obj=field,
                    id="fields.E201",
                )
            ],
        )

    def test_upload_to_starts_with_slash(self):
        class Model(models.Model):
            field = models.FileField(upload_to="/somewhere")

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "FileField's 'upload_to' argument must be a relative path, not "
                    "an absolute path.",
                    obj=field,
                    id="fields.E202",
                    hint="Remove the leading slash.",
                )
            ],
        )

    def test_upload_to_callable_not_checked(self):
        def callable(instance, filename):
            return "/" + filename

        class Model(models.Model):
            field = models.FileField(upload_to=callable)

        field = Model._meta.get_field("field")
        self.assertEqual(field.check(), [])


@isolate_apps("invalid_models_tests")
class FilePathFieldTests(SimpleTestCase):
    def test_forbidden_files_and_folders(self):
        class Model(models.Model):
            field = models.FilePathField(allow_files=False, allow_folders=False)

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    "FilePathFields must have either 'allow_files' or 'allow_folders' "
                    "set to True.",
                    obj=field,
                    id="fields.E140",
                ),
            ],
        )


@isolate_apps("invalid_models_tests")
class GenericIPAddressFieldTests(SimpleTestCase):
    def test_non_nullable_blank(self):
        class Model(models.Model):
            field = models.GenericIPAddressField(null=False, blank=True)

        field = Model._meta.get_field("field")
        self.assertEqual(
            field.check(),
            [
                Error(
                    (
                        "GenericIPAddressFields cannot have blank=True if null=False, "
                        "as blank values are stored as nulls."
                    ),
                    obj=field,
                    id="fields.E150",
                ),
            ],
        )


@isolate_apps("invalid_models_tests")
class ImageFieldTests(SimpleTestCase):
    def test_pillow_installed(self):
        try:
            from PIL import Image  # NOQA
        except ImportError:
            pillow_installed = False
        else:
            pillow_installed = True

        class Model(models.Model):
            field = models.ImageField(upload_to="somewhere")

        field = Model._meta.get_field("field")
        errors = field.check()
        expected = (
            []
            if pillow_installed
            else [
                Error(
                    "Cannot use ImageField because Pillow is not installed.",
                    hint=(
                        "Get Pillow at https://pypi.org/project/Pillow/ "
                        'or run command "python -m pip install Pillow".'
                    ),
                    obj=field,
                    id="fields.E210",
                ),
            ]
        )
        self.assertEqual(errors, expected)


@isolate_apps("invalid_models_tests")
class IntegerFieldTests(SimpleTestCase):
    def test_max_length_warning(self):
        class Model(models.Model):
            integer = models.IntegerField(max_length=2)
            biginteger = models.BigIntegerField(max_length=2)
            smallinteger = models.SmallIntegerField(max_length=2)
            positiveinteger = models.PositiveIntegerField(max_length=2)
            positivebiginteger = models.PositiveBigIntegerField(max_length=2)
            positivesmallinteger = models.PositiveSmallIntegerField(max_length=2)

        for field in Model._meta.get_fields():
            if field.auto_created:
                continue
            with self.subTest(name=field.name):
                self.assertEqual(
                    field.check(),
                    [
                        DjangoWarning(
                            "'max_length' is ignored when used with %s."
                            % field.__class__.__name__,
                            hint="Remove 'max_length' from field",
                            obj=field,
                            id="fields.W122",
                        )
                    ],
                )


@isolate_apps("invalid_models_tests")
class TimeFieldTests(SimpleTestCase):
    maxDiff = None

    def test_fix_default_value(self):
        class Model(models.Model):
            field_dt = models.TimeField(default=now())
            field_t = models.TimeField(default=now().time())
            # Timezone-aware time object (when USE_TZ=True).
            field_tz = models.TimeField(default=now().timetz())
            field_now = models.DateField(default=now)

        names = ["field_dt", "field_t", "field_tz", "field_now"]
        fields = [Model._meta.get_field(name) for name in names]
        errors = []
        for field in fields:
            errors.extend(field.check())

        self.assertEqual(
            errors,
            [
                DjangoWarning(
                    "Fixed default value provided.",
                    hint="It seems you set a fixed date / time / datetime "
                    "value as default for this field. This may not be "
                    "what you want. If you want to have the current date "
                    "as default, use `django.utils.timezone.now`",
                    obj=fields[0],
                    id="fields.W161",
                ),
                DjangoWarning(
                    "Fixed default value provided.",
                    hint="It seems you set a fixed date / time / datetime "
                    "value as default for this field. This may not be "
                    "what you want. If you want to have the current date "
                    "as default, use `django.utils.timezone.now`",
                    obj=fields[1],
                    id="fields.W161",
                ),
                DjangoWarning(
                    "Fixed default value provided.",
                    hint=(
                        "It seems you set a fixed date / time / datetime value as "
                        "default for this field. This may not be what you want. "
                        "If you want to have the current date as default, use "
                        "`django.utils.timezone.now`"
                    ),
                    obj=fields[2],
                    id="fields.W161",
                ),
                # field_now doesn't raise a warning.
            ],
        )

    @override_settings(USE_TZ=True)
    def test_fix_default_value_tz(self):
        self.test_fix_default_value()


@isolate_apps("invalid_models_tests")
class TextFieldTests(TestCase):
    @skipIfDBFeature("supports_index_on_text_field")
    def test_max_length_warning(self):
        class Model(models.Model):
            value = models.TextField(db_index=True)

        field = Model._meta.get_field("value")
        field_type = field.db_type(connection)
        self.assertEqual(
            field.check(databases=self.databases),
            [
                DjangoWarning(
                    "%s does not support a database index on %s columns."
                    % (connection.display_name, field_type),
                    hint=(
                        "An index won't be created. Silence this warning if you "
                        "don't care about it."
                    ),
                    obj=field,
                    id="fields.W162",
                )
            ],
        )

    def test_db_collation(self):
        class Model(models.Model):
            field = models.TextField(db_collation="anything")

        field = Model._meta.get_field("field")
        error = Error(
            "%s does not support a database collation on TextFields."
            % connection.display_name,
            id="fields.E190",
            obj=field,
        )
        expected = (
            [] if connection.features.supports_collation_on_textfield else [error]
        )
        self.assertEqual(field.check(databases=self.databases), expected)

    def test_db_collation_required_db_features(self):
        class Model(models.Model):
            field = models.TextField(db_collation="anything")

            class Meta:
                required_db_features = {"supports_collation_on_textfield"}

        field = Model._meta.get_field("field")
        self.assertEqual(field.check(databases=self.databases), [])


@isolate_apps("invalid_models_tests")
class UUIDFieldTests(TestCase):
    def test_choices_named_group(self):
        class Model(models.Model):
            field = models.UUIDField(
                choices=[
                    [
                        "knights",
                        [
                            [
                                uuid.UUID("5c859437-d061-4847-b3f7-e6b78852f8c8"),
                                "Lancelot",
                            ],
                            [
                                uuid.UUID("c7853ec1-2ea3-4359-b02d-b54e8f1bcee2"),
                                "Galahad",
                            ],
                        ],
                    ],
                    [uuid.UUID("25d405be-4895-4d50-9b2e-d6695359ce47"), "Other"],
                ],
            )

        self.assertEqual(Model._meta.get_field("field").check(), [])


@isolate_apps("invalid_models_tests")
@skipUnlessDBFeature("supports_json_field")
class JSONFieldTests(TestCase):
    def test_invalid_default(self):
        class Model(models.Model):
            field = models.JSONField(default={})

        self.assertEqual(
            Model._meta.get_field("field").check(),
            [
                DjangoWarning(
                    msg=(
                        "JSONField default should be a callable instead of an "
                        "instance so that it's not shared between all field "
                        "instances."
                    ),
                    hint=("Use a callable instead, e.g., use `dict` instead of `{}`."),
                    obj=Model._meta.get_field("field"),
                    id="fields.E010",
                )
            ],
        )

    def test_valid_default(self):
        class Model(models.Model):
            field = models.JSONField(default=dict)

        self.assertEqual(Model._meta.get_field("field").check(), [])

    def test_valid_default_none(self):
        class Model(models.Model):
            field = models.JSONField(default=None)

        self.assertEqual(Model._meta.get_field("field").check(), [])

    def test_valid_callable_default(self):
        def callable_default():
            return {"it": "works"}

        class Model(models.Model):
            field = models.JSONField(default=callable_default)

        self.assertEqual(Model._meta.get_field("field").check(), [])


@isolate_apps("invalid_models_tests")
class DbCommentTests(TestCase):
    def test_db_comment(self):
        class Model(models.Model):
            field = models.IntegerField(db_comment="Column comment")

        errors = Model._meta.get_field("field").check(databases=self.databases)
        expected = (
            []
            if connection.features.supports_comments
            else [
                DjangoWarning(
                    f"{connection.display_name} does not support comments on columns "
                    f"(db_comment).",
                    obj=Model._meta.get_field("field"),
                    id="fields.W163",
                ),
            ]
        )
        self.assertEqual(errors, expected)

    def test_db_comment_required_db_features(self):
        class Model(models.Model):
            field = models.IntegerField(db_comment="Column comment")

            class Meta:
                required_db_features = {"supports_comments"}

        errors = Model._meta.get_field("field").check(databases=self.databases)
        self.assertEqual(errors, [])


@isolate_apps("invalid_models_tests")
class InvalidDBDefaultTests(TestCase):
    def test_db_default(self):
        class Model(models.Model):
            field = models.FloatField(db_default=Pi())

        field = Model._meta.get_field("field")
        errors = field.check(databases=self.databases)

        if connection.features.supports_expression_defaults:
            expected_errors = []
        else:
            msg = (
                f"{connection.display_name} does not support default database values "
                "with expressions (db_default)."
            )
            expected_errors = [Error(msg=msg, obj=field, id="fields.E011")]
        self.assertEqual(errors, expected_errors)

    def test_db_default_literal(self):
        class Model(models.Model):
            field = models.IntegerField(db_default=1)

        field = Model._meta.get_field("field")
        errors = field.check(databases=self.databases)
        self.assertEqual(errors, [])

    def test_db_default_required_db_features(self):
        class Model(models.Model):
            field = models.FloatField(db_default=Pi())

            class Meta:
                required_db_features = {"supports_expression_defaults"}

        field = Model._meta.get_field("field")
        errors = field.check(databases=self.databases)
        self.assertEqual(errors, [])

    def test_db_default_expression_invalid(self):
        expression = models.F("field_name")

        class Model(models.Model):
            field = models.FloatField(db_default=expression)

        field = Model._meta.get_field("field")
        errors = field.check(databases=self.databases)

        if connection.features.supports_expression_defaults:
            msg = f"{expression} cannot be used in db_default."
            expected_errors = [Error(msg=msg, obj=field, id="fields.E012")]
        else:
            msg = (
                f"{connection.display_name} does not support default database values "
                "with expressions (db_default)."
            )
            expected_errors = [Error(msg=msg, obj=field, id="fields.E011")]
        self.assertEqual(errors, expected_errors)

    def test_db_default_expression_required_db_features(self):
        expression = models.F("field_name")

        class Model(models.Model):
            field = models.FloatField(db_default=expression)

            class Meta:
                required_db_features = {"supports_expression_defaults"}

        field = Model._meta.get_field("field")
        errors = field.check(databases=self.databases)

        if connection.features.supports_expression_defaults:
            msg = f"{expression} cannot be used in db_default."
            expected_errors = [Error(msg=msg, obj=field, id="fields.E012")]
        else:
            expected_errors = []
        self.assertEqual(errors, expected_errors)

    @skipUnlessDBFeature("supports_expression_defaults")
    def test_db_default_combined_invalid(self):
        expression = models.Value(4.5) + models.F("field_name")

        class Model(models.Model):
            field = models.FloatField(db_default=expression)

        field = Model._meta.get_field("field")
        errors = field.check(databases=self.databases)

        msg = f"{expression} cannot be used in db_default."
        expected_error = Error(msg=msg, obj=field, id="fields.E012")
        self.assertEqual(errors, [expected_error])

    @skipUnlessDBFeature("supports_expression_defaults")
    def test_db_default_function_arguments_invalid(self):
        expression = Coalesce(models.Value(4.5), models.F("field_name"))

        class Model(models.Model):
            field = models.FloatField(db_default=expression)

        field = Model._meta.get_field("field")
        errors = field.check(databases=self.databases)

        msg = f"{expression} cannot be used in db_default."
        expected_error = Error(msg=msg, obj=field, id="fields.E012")
        self.assertEqual(errors, [expected_error])