django/tests/expressions_case/tests.py

import unittest
from datetime import date, datetime, time, timedelta
from decimal import Decimal
from operator import attrgetter, itemgetter
from uuid import UUID

from django.core.exceptions import FieldError
from django.db import connection
from django.db.models import (
    BinaryField,
    BooleanField,
    Case,
    Count,
    DecimalField,
    F,
    GenericIPAddressField,
    IntegerField,
    Max,
    Min,
    Q,
    Sum,
    TextField,
    Value,
    When,
)
from django.test import SimpleTestCase, TestCase

from .models import CaseTestModel, Client, FKCaseTestModel, O2OCaseTestModel

try:
    from PIL import Image
except ImportError:
    Image = None


class CaseExpressionTests(TestCase):
    @classmethod
    def setUpTestData(cls):
        o = CaseTestModel.objects.create(integer=1, integer2=1, string="1")
        O2OCaseTestModel.objects.create(o2o=o, integer=1)
        FKCaseTestModel.objects.create(fk=o, integer=1)

        o = CaseTestModel.objects.create(integer=2, integer2=3, string="2")
        O2OCaseTestModel.objects.create(o2o=o, integer=2)
        FKCaseTestModel.objects.create(fk=o, integer=2)
        FKCaseTestModel.objects.create(fk=o, integer=3)

        o = CaseTestModel.objects.create(integer=3, integer2=4, string="3")
        O2OCaseTestModel.objects.create(o2o=o, integer=3)
        FKCaseTestModel.objects.create(fk=o, integer=3)
        FKCaseTestModel.objects.create(fk=o, integer=4)

        o = CaseTestModel.objects.create(integer=2, integer2=2, string="2")
        O2OCaseTestModel.objects.create(o2o=o, integer=2)
        FKCaseTestModel.objects.create(fk=o, integer=2)
        FKCaseTestModel.objects.create(fk=o, integer=3)

        o = CaseTestModel.objects.create(integer=3, integer2=4, string="3")
        O2OCaseTestModel.objects.create(o2o=o, integer=3)
        FKCaseTestModel.objects.create(fk=o, integer=3)
        FKCaseTestModel.objects.create(fk=o, integer=4)

        o = CaseTestModel.objects.create(integer=3, integer2=3, string="3")
        O2OCaseTestModel.objects.create(o2o=o, integer=3)
        FKCaseTestModel.objects.create(fk=o, integer=3)
        FKCaseTestModel.objects.create(fk=o, integer=4)

        o = CaseTestModel.objects.create(integer=4, integer2=5, string="4")
        O2OCaseTestModel.objects.create(o2o=o, integer=1)
        FKCaseTestModel.objects.create(fk=o, integer=5)

        cls.group_by_fields = [
            f.name
            for f in CaseTestModel._meta.get_fields()
            if not (f.is_relation and f.auto_created)
            and (
                connection.features.allows_group_by_lob
                or not isinstance(f, (BinaryField, TextField))
            )
        ]

    def test_annotate(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                test=Case(
                    When(integer=1, then=Value("one")),
                    When(integer=2, then=Value("two")),
                    default=Value("other"),
                )
            ).order_by("pk"),
            [
                (1, "one"),
                (2, "two"),
                (3, "other"),
                (2, "two"),
                (3, "other"),
                (3, "other"),
                (4, "other"),
            ],
            transform=attrgetter("integer", "test"),
        )

    def test_annotate_without_default(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                test=Case(
                    When(integer=1, then=1),
                    When(integer=2, then=2),
                )
            ).order_by("pk"),
            [(1, 1), (2, 2), (3, None), (2, 2), (3, None), (3, None), (4, None)],
            transform=attrgetter("integer", "test"),
        )

    def test_annotate_with_expression_as_value(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                f_test=Case(
                    When(integer=1, then=F("integer") + 1),
                    When(integer=2, then=F("integer") + 3),
                    default="integer",
                )
            ).order_by("pk"),
            [(1, 2), (2, 5), (3, 3), (2, 5), (3, 3), (3, 3), (4, 4)],
            transform=attrgetter("integer", "f_test"),
        )

    def test_annotate_with_expression_as_condition(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                f_test=Case(
                    When(integer2=F("integer"), then=Value("equal")),
                    When(integer2=F("integer") + 1, then=Value("+1")),
                )
            ).order_by("pk"),
            [
                (1, "equal"),
                (2, "+1"),
                (3, "+1"),
                (2, "equal"),
                (3, "+1"),
                (3, "equal"),
                (4, "+1"),
            ],
            transform=attrgetter("integer", "f_test"),
        )

    def test_annotate_with_join_in_value(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                join_test=Case(
                    When(integer=1, then=F("o2o_rel__integer") + 1),
                    When(integer=2, then=F("o2o_rel__integer") + 3),
                    default="o2o_rel__integer",
                )
            ).order_by("pk"),
            [(1, 2), (2, 5), (3, 3), (2, 5), (3, 3), (3, 3), (4, 1)],
            transform=attrgetter("integer", "join_test"),
        )

    def test_annotate_with_in_clause(self):
        fk_rels = FKCaseTestModel.objects.filter(integer__in=[5])
        self.assertQuerysetEqual(
            CaseTestModel.objects.only("pk", "integer")
            .annotate(
                in_test=Sum(
                    Case(
                        When(fk_rel__in=fk_rels, then=F("fk_rel__integer")),
                        default=Value(0),
                    )
                )
            )
            .order_by("pk"),
            [(1, 0), (2, 0), (3, 0), (2, 0), (3, 0), (3, 0), (4, 5)],
            transform=attrgetter("integer", "in_test"),
        )

    def test_annotate_with_join_in_condition(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                join_test=Case(
                    When(integer2=F("o2o_rel__integer"), then=Value("equal")),
                    When(integer2=F("o2o_rel__integer") + 1, then=Value("+1")),
                    default=Value("other"),
                )
            ).order_by("pk"),
            [
                (1, "equal"),
                (2, "+1"),
                (3, "+1"),
                (2, "equal"),
                (3, "+1"),
                (3, "equal"),
                (4, "other"),
            ],
            transform=attrgetter("integer", "join_test"),
        )

    def test_annotate_with_join_in_predicate(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                join_test=Case(
                    When(o2o_rel__integer=1, then=Value("one")),
                    When(o2o_rel__integer=2, then=Value("two")),
                    When(o2o_rel__integer=3, then=Value("three")),
                    default=Value("other"),
                )
            ).order_by("pk"),
            [
                (1, "one"),
                (2, "two"),
                (3, "three"),
                (2, "two"),
                (3, "three"),
                (3, "three"),
                (4, "one"),
            ],
            transform=attrgetter("integer", "join_test"),
        )

    def test_annotate_with_annotation_in_value(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                f_plus_1=F("integer") + 1,
                f_plus_3=F("integer") + 3,
            )
            .annotate(
                f_test=Case(
                    When(integer=1, then="f_plus_1"),
                    When(integer=2, then="f_plus_3"),
                    default="integer",
                ),
            )
            .order_by("pk"),
            [(1, 2), (2, 5), (3, 3), (2, 5), (3, 3), (3, 3), (4, 4)],
            transform=attrgetter("integer", "f_test"),
        )

    def test_annotate_with_annotation_in_condition(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                f_plus_1=F("integer") + 1,
            )
            .annotate(
                f_test=Case(
                    When(integer2=F("integer"), then=Value("equal")),
                    When(integer2=F("f_plus_1"), then=Value("+1")),
                ),
            )
            .order_by("pk"),
            [
                (1, "equal"),
                (2, "+1"),
                (3, "+1"),
                (2, "equal"),
                (3, "+1"),
                (3, "equal"),
                (4, "+1"),
            ],
            transform=attrgetter("integer", "f_test"),
        )

    def test_annotate_with_annotation_in_predicate(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                f_minus_2=F("integer") - 2,
            )
            .annotate(
                test=Case(
                    When(f_minus_2=-1, then=Value("negative one")),
                    When(f_minus_2=0, then=Value("zero")),
                    When(f_minus_2=1, then=Value("one")),
                    default=Value("other"),
                ),
            )
            .order_by("pk"),
            [
                (1, "negative one"),
                (2, "zero"),
                (3, "one"),
                (2, "zero"),
                (3, "one"),
                (3, "one"),
                (4, "other"),
            ],
            transform=attrgetter("integer", "test"),
        )

    def test_annotate_with_aggregation_in_value(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.values(*self.group_by_fields)
            .annotate(
                min=Min("fk_rel__integer"),
                max=Max("fk_rel__integer"),
            )
            .annotate(
                test=Case(
                    When(integer=2, then="min"),
                    When(integer=3, then="max"),
                ),
            )
            .order_by("pk"),
            [
                (1, None, 1, 1),
                (2, 2, 2, 3),
                (3, 4, 3, 4),
                (2, 2, 2, 3),
                (3, 4, 3, 4),
                (3, 4, 3, 4),
                (4, None, 5, 5),
            ],
            transform=itemgetter("integer", "test", "min", "max"),
        )

    def test_annotate_with_aggregation_in_condition(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.values(*self.group_by_fields)
            .annotate(
                min=Min("fk_rel__integer"),
                max=Max("fk_rel__integer"),
            )
            .annotate(
                test=Case(
                    When(integer2=F("min"), then=Value("min")),
                    When(integer2=F("max"), then=Value("max")),
                ),
            )
            .order_by("pk"),
            [
                (1, 1, "min"),
                (2, 3, "max"),
                (3, 4, "max"),
                (2, 2, "min"),
                (3, 4, "max"),
                (3, 3, "min"),
                (4, 5, "min"),
            ],
            transform=itemgetter("integer", "integer2", "test"),
        )

    def test_annotate_with_aggregation_in_predicate(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.values(*self.group_by_fields)
            .annotate(
                max=Max("fk_rel__integer"),
            )
            .annotate(
                test=Case(
                    When(max=3, then=Value("max = 3")),
                    When(max=4, then=Value("max = 4")),
                    default=Value(""),
                ),
            )
            .order_by("pk"),
            [
                (1, 1, ""),
                (2, 3, "max = 3"),
                (3, 4, "max = 4"),
                (2, 3, "max = 3"),
                (3, 4, "max = 4"),
                (3, 4, "max = 4"),
                (4, 5, ""),
            ],
            transform=itemgetter("integer", "max", "test"),
        )

    def test_annotate_exclude(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                test=Case(
                    When(integer=1, then=Value("one")),
                    When(integer=2, then=Value("two")),
                    default=Value("other"),
                )
            )
            .exclude(test="other")
            .order_by("pk"),
            [(1, "one"), (2, "two"), (2, "two")],
            transform=attrgetter("integer", "test"),
        )

    def test_annotate_filter_decimal(self):
        obj = CaseTestModel.objects.create(integer=0, decimal=Decimal("1"))
        qs = CaseTestModel.objects.annotate(
            x=Case(When(integer=0, then=F("decimal"))),
            y=Case(When(integer=0, then=Value(Decimal("1")))),
        )
        self.assertSequenceEqual(qs.filter(Q(x=1) & Q(x=Decimal("1"))), [obj])
        self.assertSequenceEqual(qs.filter(Q(y=1) & Q(y=Decimal("1"))), [obj])

    def test_annotate_values_not_in_order_by(self):
        self.assertEqual(
            list(
                CaseTestModel.objects.annotate(
                    test=Case(
                        When(integer=1, then=Value("one")),
                        When(integer=2, then=Value("two")),
                        When(integer=3, then=Value("three")),
                        default=Value("other"),
                    )
                )
                .order_by("test")
                .values_list("integer", flat=True)
            ),
            [1, 4, 3, 3, 3, 2, 2],
        )

    def test_annotate_with_empty_when(self):
        objects = CaseTestModel.objects.annotate(
            selected=Case(
                When(pk__in=[], then=Value("selected")),
                default=Value("not selected"),
            )
        )
        self.assertEqual(len(objects), CaseTestModel.objects.count())
        self.assertTrue(all(obj.selected == "not selected" for obj in objects))

    def test_combined_expression(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                test=Case(
                    When(integer=1, then=2),
                    When(integer=2, then=1),
                    default=3,
                )
                + 1,
            ).order_by("pk"),
            [(1, 3), (2, 2), (3, 4), (2, 2), (3, 4), (3, 4), (4, 4)],
            transform=attrgetter("integer", "test"),
        )

    def test_in_subquery(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(
                pk__in=CaseTestModel.objects.annotate(
                    test=Case(
                        When(integer=F("integer2"), then="pk"),
                        When(integer=4, then="pk"),
                    ),
                ).values("test")
            ).order_by("pk"),
            [(1, 1), (2, 2), (3, 3), (4, 5)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_condition_with_lookups(self):
        qs = CaseTestModel.objects.annotate(
            test=Case(
                When(Q(integer2=1), string="2", then=Value(False)),
                When(Q(integer2=1), string="1", then=Value(True)),
                default=Value(False),
                output_field=BooleanField(),
            ),
        )
        self.assertIs(qs.get(integer=1).test, True)

    def test_case_reuse(self):
        SOME_CASE = Case(
            When(pk=0, then=Value("0")),
            default=Value("1"),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(somecase=SOME_CASE).order_by("pk"),
            CaseTestModel.objects.annotate(somecase=SOME_CASE)
            .order_by("pk")
            .values_list("pk", "somecase"),
            lambda x: (x.pk, x.somecase),
        )

    def test_aggregate(self):
        self.assertEqual(
            CaseTestModel.objects.aggregate(
                one=Sum(
                    Case(
                        When(integer=1, then=1),
                    )
                ),
                two=Sum(
                    Case(
                        When(integer=2, then=1),
                    )
                ),
                three=Sum(
                    Case(
                        When(integer=3, then=1),
                    )
                ),
                four=Sum(
                    Case(
                        When(integer=4, then=1),
                    )
                ),
            ),
            {"one": 1, "two": 2, "three": 3, "four": 1},
        )

    def test_aggregate_with_expression_as_value(self):
        self.assertEqual(
            CaseTestModel.objects.aggregate(
                one=Sum(Case(When(integer=1, then="integer"))),
                two=Sum(Case(When(integer=2, then=F("integer") - 1))),
                three=Sum(Case(When(integer=3, then=F("integer") + 1))),
            ),
            {"one": 1, "two": 2, "three": 12},
        )

    def test_aggregate_with_expression_as_condition(self):
        self.assertEqual(
            CaseTestModel.objects.aggregate(
                equal=Sum(
                    Case(
                        When(integer2=F("integer"), then=1),
                    )
                ),
                plus_one=Sum(
                    Case(
                        When(integer2=F("integer") + 1, then=1),
                    )
                ),
            ),
            {"equal": 3, "plus_one": 4},
        )

    def test_filter(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(
                integer2=Case(
                    When(integer=2, then=3),
                    When(integer=3, then=4),
                    default=1,
                )
            ).order_by("pk"),
            [(1, 1), (2, 3), (3, 4), (3, 4)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_filter_without_default(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(
                integer2=Case(
                    When(integer=2, then=3),
                    When(integer=3, then=4),
                )
            ).order_by("pk"),
            [(2, 3), (3, 4), (3, 4)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_filter_with_expression_as_value(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(
                integer2=Case(
                    When(integer=2, then=F("integer") + 1),
                    When(integer=3, then=F("integer")),
                    default="integer",
                )
            ).order_by("pk"),
            [(1, 1), (2, 3), (3, 3)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_filter_with_expression_as_condition(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(
                string=Case(
                    When(integer2=F("integer"), then=Value("2")),
                    When(integer2=F("integer") + 1, then=Value("3")),
                )
            ).order_by("pk"),
            [(3, 4, "3"), (2, 2, "2"), (3, 4, "3")],
            transform=attrgetter("integer", "integer2", "string"),
        )

    def test_filter_with_join_in_value(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(
                integer2=Case(
                    When(integer=2, then=F("o2o_rel__integer") + 1),
                    When(integer=3, then=F("o2o_rel__integer")),
                    default="o2o_rel__integer",
                )
            ).order_by("pk"),
            [(1, 1), (2, 3), (3, 3)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_filter_with_join_in_condition(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(
                integer=Case(
                    When(integer2=F("o2o_rel__integer") + 1, then=2),
                    When(integer2=F("o2o_rel__integer"), then=3),
                )
            ).order_by("pk"),
            [(2, 3), (3, 3)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_filter_with_join_in_predicate(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(
                integer2=Case(
                    When(o2o_rel__integer=1, then=1),
                    When(o2o_rel__integer=2, then=3),
                    When(o2o_rel__integer=3, then=4),
                )
            ).order_by("pk"),
            [(1, 1), (2, 3), (3, 4), (3, 4)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_filter_with_annotation_in_value(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                f=F("integer"),
                f_plus_1=F("integer") + 1,
            )
            .filter(
                integer2=Case(
                    When(integer=2, then="f_plus_1"),
                    When(integer=3, then="f"),
                ),
            )
            .order_by("pk"),
            [(2, 3), (3, 3)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_filter_with_annotation_in_condition(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                f_plus_1=F("integer") + 1,
            )
            .filter(
                integer=Case(
                    When(integer2=F("integer"), then=2),
                    When(integer2=F("f_plus_1"), then=3),
                ),
            )
            .order_by("pk"),
            [(3, 4), (2, 2), (3, 4)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_filter_with_annotation_in_predicate(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                f_plus_1=F("integer") + 1,
            )
            .filter(
                integer2=Case(
                    When(f_plus_1=3, then=3),
                    When(f_plus_1=4, then=4),
                    default=1,
                ),
            )
            .order_by("pk"),
            [(1, 1), (2, 3), (3, 4), (3, 4)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_filter_with_aggregation_in_value(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.values(*self.group_by_fields)
            .annotate(
                min=Min("fk_rel__integer"),
                max=Max("fk_rel__integer"),
            )
            .filter(
                integer2=Case(
                    When(integer=2, then="min"),
                    When(integer=3, then="max"),
                ),
            )
            .order_by("pk"),
            [(3, 4, 3, 4), (2, 2, 2, 3), (3, 4, 3, 4)],
            transform=itemgetter("integer", "integer2", "min", "max"),
        )

    def test_filter_with_aggregation_in_condition(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.values(*self.group_by_fields)
            .annotate(
                min=Min("fk_rel__integer"),
                max=Max("fk_rel__integer"),
            )
            .filter(
                integer=Case(
                    When(integer2=F("min"), then=2),
                    When(integer2=F("max"), then=3),
                ),
            )
            .order_by("pk"),
            [(3, 4, 3, 4), (2, 2, 2, 3), (3, 4, 3, 4)],
            transform=itemgetter("integer", "integer2", "min", "max"),
        )

    def test_filter_with_aggregation_in_predicate(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.values(*self.group_by_fields)
            .annotate(
                max=Max("fk_rel__integer"),
            )
            .filter(
                integer=Case(
                    When(max=3, then=2),
                    When(max=4, then=3),
                ),
            )
            .order_by("pk"),
            [(2, 3, 3), (3, 4, 4), (2, 2, 3), (3, 4, 4), (3, 3, 4)],
            transform=itemgetter("integer", "integer2", "max"),
        )

    def test_update(self):
        CaseTestModel.objects.update(
            string=Case(
                When(integer=1, then=Value("one")),
                When(integer=2, then=Value("two")),
                default=Value("other"),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, "one"),
                (2, "two"),
                (3, "other"),
                (2, "two"),
                (3, "other"),
                (3, "other"),
                (4, "other"),
            ],
            transform=attrgetter("integer", "string"),
        )

    def test_update_without_default(self):
        CaseTestModel.objects.update(
            integer2=Case(
                When(integer=1, then=1),
                When(integer=2, then=2),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, 1), (2, 2), (3, None), (2, 2), (3, None), (3, None), (4, None)],
            transform=attrgetter("integer", "integer2"),
        )

    def test_update_with_expression_as_value(self):
        CaseTestModel.objects.update(
            integer=Case(
                When(integer=1, then=F("integer") + 1),
                When(integer=2, then=F("integer") + 3),
                default="integer",
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [("1", 2), ("2", 5), ("3", 3), ("2", 5), ("3", 3), ("3", 3), ("4", 4)],
            transform=attrgetter("string", "integer"),
        )

    def test_update_with_expression_as_condition(self):
        CaseTestModel.objects.update(
            string=Case(
                When(integer2=F("integer"), then=Value("equal")),
                When(integer2=F("integer") + 1, then=Value("+1")),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, "equal"),
                (2, "+1"),
                (3, "+1"),
                (2, "equal"),
                (3, "+1"),
                (3, "equal"),
                (4, "+1"),
            ],
            transform=attrgetter("integer", "string"),
        )

    def test_update_with_join_in_condition_raise_field_error(self):
        with self.assertRaisesMessage(
            FieldError, "Joined field references are not permitted in this query"
        ):
            CaseTestModel.objects.update(
                integer=Case(
                    When(integer2=F("o2o_rel__integer") + 1, then=2),
                    When(integer2=F("o2o_rel__integer"), then=3),
                ),
            )

    def test_update_with_join_in_predicate_raise_field_error(self):
        with self.assertRaisesMessage(
            FieldError, "Joined field references are not permitted in this query"
        ):
            CaseTestModel.objects.update(
                string=Case(
                    When(o2o_rel__integer=1, then=Value("one")),
                    When(o2o_rel__integer=2, then=Value("two")),
                    When(o2o_rel__integer=3, then=Value("three")),
                    default=Value("other"),
                ),
            )

    def test_update_big_integer(self):
        CaseTestModel.objects.update(
            big_integer=Case(
                When(integer=1, then=1),
                When(integer=2, then=2),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, 1), (2, 2), (3, None), (2, 2), (3, None), (3, None), (4, None)],
            transform=attrgetter("integer", "big_integer"),
        )

    def test_update_binary(self):
        CaseTestModel.objects.update(
            binary=Case(
                When(integer=1, then=b"one"),
                When(integer=2, then=b"two"),
                default=b"",
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, b"one"),
                (2, b"two"),
                (3, b""),
                (2, b"two"),
                (3, b""),
                (3, b""),
                (4, b""),
            ],
            transform=lambda o: (o.integer, bytes(o.binary)),
        )

    def test_update_boolean(self):
        CaseTestModel.objects.update(
            boolean=Case(
                When(integer=1, then=True),
                When(integer=2, then=True),
                default=False,
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, True),
                (2, True),
                (3, False),
                (2, True),
                (3, False),
                (3, False),
                (4, False),
            ],
            transform=attrgetter("integer", "boolean"),
        )

    def test_update_date(self):
        CaseTestModel.objects.update(
            date=Case(
                When(integer=1, then=date(2015, 1, 1)),
                When(integer=2, then=date(2015, 1, 2)),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, date(2015, 1, 1)),
                (2, date(2015, 1, 2)),
                (3, None),
                (2, date(2015, 1, 2)),
                (3, None),
                (3, None),
                (4, None),
            ],
            transform=attrgetter("integer", "date"),
        )

    def test_update_date_time(self):
        CaseTestModel.objects.update(
            date_time=Case(
                When(integer=1, then=datetime(2015, 1, 1)),
                When(integer=2, then=datetime(2015, 1, 2)),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, datetime(2015, 1, 1)),
                (2, datetime(2015, 1, 2)),
                (3, None),
                (2, datetime(2015, 1, 2)),
                (3, None),
                (3, None),
                (4, None),
            ],
            transform=attrgetter("integer", "date_time"),
        )

    def test_update_decimal(self):
        CaseTestModel.objects.update(
            decimal=Case(
                When(integer=1, then=Decimal("1.1")),
                When(
                    integer=2, then=Value(Decimal("2.2"), output_field=DecimalField())
                ),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, Decimal("1.1")),
                (2, Decimal("2.2")),
                (3, None),
                (2, Decimal("2.2")),
                (3, None),
                (3, None),
                (4, None),
            ],
            transform=attrgetter("integer", "decimal"),
        )

    def test_update_duration(self):
        CaseTestModel.objects.update(
            duration=Case(
                When(integer=1, then=timedelta(1)),
                When(integer=2, then=timedelta(2)),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, timedelta(1)),
                (2, timedelta(2)),
                (3, None),
                (2, timedelta(2)),
                (3, None),
                (3, None),
                (4, None),
            ],
            transform=attrgetter("integer", "duration"),
        )

    def test_update_email(self):
        CaseTestModel.objects.update(
            email=Case(
                When(integer=1, then=Value("1@example.com")),
                When(integer=2, then=Value("2@example.com")),
                default=Value(""),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, "1@example.com"),
                (2, "2@example.com"),
                (3, ""),
                (2, "2@example.com"),
                (3, ""),
                (3, ""),
                (4, ""),
            ],
            transform=attrgetter("integer", "email"),
        )

    def test_update_file(self):
        CaseTestModel.objects.update(
            file=Case(
                When(integer=1, then=Value("~/1")),
                When(integer=2, then=Value("~/2")),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, "~/1"), (2, "~/2"), (3, ""), (2, "~/2"), (3, ""), (3, ""), (4, "")],
            transform=lambda o: (o.integer, str(o.file)),
        )

    def test_update_file_path(self):
        CaseTestModel.objects.update(
            file_path=Case(
                When(integer=1, then=Value("~/1")),
                When(integer=2, then=Value("~/2")),
                default=Value(""),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, "~/1"), (2, "~/2"), (3, ""), (2, "~/2"), (3, ""), (3, ""), (4, "")],
            transform=attrgetter("integer", "file_path"),
        )

    def test_update_float(self):
        CaseTestModel.objects.update(
            float=Case(
                When(integer=1, then=1.1),
                When(integer=2, then=2.2),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, 1.1), (2, 2.2), (3, None), (2, 2.2), (3, None), (3, None), (4, None)],
            transform=attrgetter("integer", "float"),
        )

    @unittest.skipUnless(Image, "Pillow not installed")
    def test_update_image(self):
        CaseTestModel.objects.update(
            image=Case(
                When(integer=1, then=Value("~/1")),
                When(integer=2, then=Value("~/2")),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, "~/1"), (2, "~/2"), (3, ""), (2, "~/2"), (3, ""), (3, ""), (4, "")],
            transform=lambda o: (o.integer, str(o.image)),
        )

    def test_update_generic_ip_address(self):
        CaseTestModel.objects.update(
            generic_ip_address=Case(
                When(integer=1, then=Value("1.1.1.1")),
                When(integer=2, then=Value("2.2.2.2")),
                output_field=GenericIPAddressField(),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, "1.1.1.1"),
                (2, "2.2.2.2"),
                (3, None),
                (2, "2.2.2.2"),
                (3, None),
                (3, None),
                (4, None),
            ],
            transform=attrgetter("integer", "generic_ip_address"),
        )

    def test_update_null_boolean(self):
        CaseTestModel.objects.update(
            null_boolean=Case(
                When(integer=1, then=True),
                When(integer=2, then=False),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, True),
                (2, False),
                (3, None),
                (2, False),
                (3, None),
                (3, None),
                (4, None),
            ],
            transform=attrgetter("integer", "null_boolean"),
        )

    def test_update_positive_big_integer(self):
        CaseTestModel.objects.update(
            positive_big_integer=Case(
                When(integer=1, then=1),
                When(integer=2, then=2),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, 1), (2, 2), (3, None), (2, 2), (3, None), (3, None), (4, None)],
            transform=attrgetter("integer", "positive_big_integer"),
        )

    def test_update_positive_integer(self):
        CaseTestModel.objects.update(
            positive_integer=Case(
                When(integer=1, then=1),
                When(integer=2, then=2),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, 1), (2, 2), (3, None), (2, 2), (3, None), (3, None), (4, None)],
            transform=attrgetter("integer", "positive_integer"),
        )

    def test_update_positive_small_integer(self):
        CaseTestModel.objects.update(
            positive_small_integer=Case(
                When(integer=1, then=1),
                When(integer=2, then=2),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, 1), (2, 2), (3, None), (2, 2), (3, None), (3, None), (4, None)],
            transform=attrgetter("integer", "positive_small_integer"),
        )

    def test_update_slug(self):
        CaseTestModel.objects.update(
            slug=Case(
                When(integer=1, then=Value("1")),
                When(integer=2, then=Value("2")),
                default=Value(""),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, "1"), (2, "2"), (3, ""), (2, "2"), (3, ""), (3, ""), (4, "")],
            transform=attrgetter("integer", "slug"),
        )

    def test_update_small_integer(self):
        CaseTestModel.objects.update(
            small_integer=Case(
                When(integer=1, then=1),
                When(integer=2, then=2),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, 1), (2, 2), (3, None), (2, 2), (3, None), (3, None), (4, None)],
            transform=attrgetter("integer", "small_integer"),
        )

    def test_update_string(self):
        CaseTestModel.objects.filter(string__in=["1", "2"]).update(
            string=Case(
                When(integer=1, then=Value("1")),
                When(integer=2, then=Value("2")),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(string__in=["1", "2"]).order_by("pk"),
            [(1, "1"), (2, "2"), (2, "2")],
            transform=attrgetter("integer", "string"),
        )

    def test_update_text(self):
        CaseTestModel.objects.update(
            text=Case(
                When(integer=1, then=Value("1")),
                When(integer=2, then=Value("2")),
                default=Value(""),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [(1, "1"), (2, "2"), (3, ""), (2, "2"), (3, ""), (3, ""), (4, "")],
            transform=attrgetter("integer", "text"),
        )

    def test_update_time(self):
        CaseTestModel.objects.update(
            time=Case(
                When(integer=1, then=time(1)),
                When(integer=2, then=time(2)),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, time(1)),
                (2, time(2)),
                (3, None),
                (2, time(2)),
                (3, None),
                (3, None),
                (4, None),
            ],
            transform=attrgetter("integer", "time"),
        )

    def test_update_url(self):
        CaseTestModel.objects.update(
            url=Case(
                When(integer=1, then=Value("http://1.example.com/")),
                When(integer=2, then=Value("http://2.example.com/")),
                default=Value(""),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, "http://1.example.com/"),
                (2, "http://2.example.com/"),
                (3, ""),
                (2, "http://2.example.com/"),
                (3, ""),
                (3, ""),
                (4, ""),
            ],
            transform=attrgetter("integer", "url"),
        )

    def test_update_uuid(self):
        CaseTestModel.objects.update(
            uuid=Case(
                When(integer=1, then=UUID("11111111111111111111111111111111")),
                When(integer=2, then=UUID("22222222222222222222222222222222")),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, UUID("11111111111111111111111111111111")),
                (2, UUID("22222222222222222222222222222222")),
                (3, None),
                (2, UUID("22222222222222222222222222222222")),
                (3, None),
                (3, None),
                (4, None),
            ],
            transform=attrgetter("integer", "uuid"),
        )

    def test_update_fk(self):
        obj1, obj2 = CaseTestModel.objects.all()[:2]

        CaseTestModel.objects.update(
            fk=Case(
                When(integer=1, then=obj1.pk),
                When(integer=2, then=obj2.pk),
            ),
        )
        self.assertQuerysetEqual(
            CaseTestModel.objects.order_by("pk"),
            [
                (1, obj1.pk),
                (2, obj2.pk),
                (3, None),
                (2, obj2.pk),
                (3, None),
                (3, None),
                (4, None),
            ],
            transform=attrgetter("integer", "fk_id"),
        )

    def test_lookup_in_condition(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                test=Case(
                    When(integer__lt=2, then=Value("less than 2")),
                    When(integer__gt=2, then=Value("greater than 2")),
                    default=Value("equal to 2"),
                ),
            ).order_by("pk"),
            [
                (1, "less than 2"),
                (2, "equal to 2"),
                (3, "greater than 2"),
                (2, "equal to 2"),
                (3, "greater than 2"),
                (3, "greater than 2"),
                (4, "greater than 2"),
            ],
            transform=attrgetter("integer", "test"),
        )

    def test_lookup_different_fields(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                test=Case(
                    When(integer=2, integer2=3, then=Value("when")),
                    default=Value("default"),
                ),
            ).order_by("pk"),
            [
                (1, 1, "default"),
                (2, 3, "when"),
                (3, 4, "default"),
                (2, 2, "default"),
                (3, 4, "default"),
                (3, 3, "default"),
                (4, 5, "default"),
            ],
            transform=attrgetter("integer", "integer2", "test"),
        )

    def test_combined_q_object(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.annotate(
                test=Case(
                    When(Q(integer=2) | Q(integer2=3), then=Value("when")),
                    default=Value("default"),
                ),
            ).order_by("pk"),
            [
                (1, 1, "default"),
                (2, 3, "when"),
                (3, 4, "default"),
                (2, 2, "when"),
                (3, 4, "default"),
                (3, 3, "when"),
                (4, 5, "default"),
            ],
            transform=attrgetter("integer", "integer2", "test"),
        )

    def test_order_by_conditional_implicit(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(integer__lte=2)
            .annotate(
                test=Case(
                    When(integer=1, then=2),
                    When(integer=2, then=1),
                    default=3,
                )
            )
            .order_by("test", "pk"),
            [(2, 1), (2, 1), (1, 2)],
            transform=attrgetter("integer", "test"),
        )

    def test_order_by_conditional_explicit(self):
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(integer__lte=2)
            .annotate(
                test=Case(
                    When(integer=1, then=2),
                    When(integer=2, then=1),
                    default=3,
                )
            )
            .order_by(F("test").asc(), "pk"),
            [(2, 1), (2, 1), (1, 2)],
            transform=attrgetter("integer", "test"),
        )

    def test_join_promotion(self):
        o = CaseTestModel.objects.create(integer=1, integer2=1, string="1")
        # Testing that:
        # 1. There isn't any object on the remote side of the fk_rel
        #    relation. If the query used inner joins, then the join to fk_rel
        #    would remove o from the results. So, in effect we are testing that
        #    we are promoting the fk_rel join to a left outer join here.
        # 2. The default value of 3 is generated for the case expression.
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(pk=o.pk).annotate(
                foo=Case(
                    When(fk_rel__pk=1, then=2),
                    default=3,
                ),
            ),
            [(o, 3)],
            lambda x: (x, x.foo),
        )
        # Now 2 should be generated, as the fk_rel is null.
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(pk=o.pk).annotate(
                foo=Case(
                    When(fk_rel__isnull=True, then=2),
                    default=3,
                ),
            ),
            [(o, 2)],
            lambda x: (x, x.foo),
        )

    def test_join_promotion_multiple_annotations(self):
        o = CaseTestModel.objects.create(integer=1, integer2=1, string="1")
        # Testing that:
        # 1. There isn't any object on the remote side of the fk_rel
        #    relation. If the query used inner joins, then the join to fk_rel
        #    would remove o from the results. So, in effect we are testing that
        #    we are promoting the fk_rel join to a left outer join here.
        # 2. The default value of 3 is generated for the case expression.
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(pk=o.pk).annotate(
                foo=Case(
                    When(fk_rel__pk=1, then=2),
                    default=3,
                ),
                bar=Case(
                    When(fk_rel__pk=1, then=4),
                    default=5,
                ),
            ),
            [(o, 3, 5)],
            lambda x: (x, x.foo, x.bar),
        )
        # Now 2 should be generated, as the fk_rel is null.
        self.assertQuerysetEqual(
            CaseTestModel.objects.filter(pk=o.pk).annotate(
                foo=Case(
                    When(fk_rel__isnull=True, then=2),
                    default=3,
                ),
                bar=Case(
                    When(fk_rel__isnull=True, then=4),
                    default=5,
                ),
            ),
            [(o, 2, 4)],
            lambda x: (x, x.foo, x.bar),
        )

    def test_m2m_exclude(self):
        CaseTestModel.objects.create(integer=10, integer2=1, string="1")
        qs = (
            CaseTestModel.objects.values_list("id", "integer")
            .annotate(
                cnt=Sum(
                    Case(When(~Q(fk_rel__integer=1), then=1), default=2),
                ),
            )
            .order_by("integer")
        )
        # The first o has 2 as its fk_rel__integer=1, thus it hits the
        # default=2 case. The other ones have 2 as the result as they have 2
        # fk_rel objects, except for integer=4 and integer=10 (created above).
        # The integer=4 case has one integer, thus the result is 1, and
        # integer=10 doesn't have any and this too generates 1 (instead of 0)
        # as ~Q() also matches nulls.
        self.assertQuerysetEqual(
            qs,
            [(1, 2), (2, 2), (2, 2), (3, 2), (3, 2), (3, 2), (4, 1), (10, 1)],
            lambda x: x[1:],
        )

    def test_m2m_reuse(self):
        CaseTestModel.objects.create(integer=10, integer2=1, string="1")
        # Need to use values before annotate so that Oracle will not group
        # by fields it isn't capable of grouping by.
        qs = (
            CaseTestModel.objects.values_list("id", "integer")
            .annotate(
                cnt=Sum(
                    Case(When(~Q(fk_rel__integer=1), then=1), default=2),
                ),
            )
            .annotate(
                cnt2=Sum(
                    Case(When(~Q(fk_rel__integer=1), then=1), default=2),
                ),
            )
            .order_by("integer")
        )
        self.assertEqual(str(qs.query).count(" JOIN "), 1)
        self.assertQuerysetEqual(
            qs,
            [
                (1, 2, 2),
                (2, 2, 2),
                (2, 2, 2),
                (3, 2, 2),
                (3, 2, 2),
                (3, 2, 2),
                (4, 1, 1),
                (10, 1, 1),
            ],
            lambda x: x[1:],
        )

    def test_aggregation_empty_cases(self):
        tests = [
            # Empty cases and default.
            (Case(output_field=IntegerField()), None),
            # Empty cases and a constant default.
            (Case(default=Value("empty")), "empty"),
            # Empty cases and column in the default.
            (Case(default=F("url")), ""),
        ]
        for case, value in tests:
            with self.subTest(case=case):
                self.assertQuerysetEqual(
                    CaseTestModel.objects.values("string")
                    .annotate(
                        case=case,
                        integer_sum=Sum("integer"),
                    )
                    .order_by("string"),
                    [
                        ("1", value, 1),
                        ("2", value, 4),
                        ("3", value, 9),
                        ("4", value, 4),
                    ],
                    transform=itemgetter("string", "case", "integer_sum"),
                )


class CaseDocumentationExamples(TestCase):
    @classmethod
    def setUpTestData(cls):
        Client.objects.create(
            name="Jane Doe",
            account_type=Client.REGULAR,
            registered_on=date.today() - timedelta(days=36),
        )
        Client.objects.create(
            name="James Smith",
            account_type=Client.GOLD,
            registered_on=date.today() - timedelta(days=5),
        )
        Client.objects.create(
            name="Jack Black",
            account_type=Client.PLATINUM,
            registered_on=date.today() - timedelta(days=10 * 365),
        )

    def test_simple_example(self):
        self.assertQuerysetEqual(
            Client.objects.annotate(
                discount=Case(
                    When(account_type=Client.GOLD, then=Value("5%")),
                    When(account_type=Client.PLATINUM, then=Value("10%")),
                    default=Value("0%"),
                ),
            ).order_by("pk"),
            [("Jane Doe", "0%"), ("James Smith", "5%"), ("Jack Black", "10%")],
            transform=attrgetter("name", "discount"),
        )

    def test_lookup_example(self):
        a_month_ago = date.today() - timedelta(days=30)
        a_year_ago = date.today() - timedelta(days=365)
        self.assertQuerysetEqual(
            Client.objects.annotate(
                discount=Case(
                    When(registered_on__lte=a_year_ago, then=Value("10%")),
                    When(registered_on__lte=a_month_ago, then=Value("5%")),
                    default=Value("0%"),
                ),
            ).order_by("pk"),
            [("Jane Doe", "5%"), ("James Smith", "0%"), ("Jack Black", "10%")],
            transform=attrgetter("name", "discount"),
        )

    def test_conditional_update_example(self):
        a_month_ago = date.today() - timedelta(days=30)
        a_year_ago = date.today() - timedelta(days=365)
        Client.objects.update(
            account_type=Case(
                When(registered_on__lte=a_year_ago, then=Value(Client.PLATINUM)),
                When(registered_on__lte=a_month_ago, then=Value(Client.GOLD)),
                default=Value(Client.REGULAR),
            ),
        )
        self.assertQuerysetEqual(
            Client.objects.order_by("pk"),
            [("Jane Doe", "G"), ("James Smith", "R"), ("Jack Black", "P")],
            transform=attrgetter("name", "account_type"),
        )

    def test_conditional_aggregation_example(self):
        Client.objects.create(
            name="Jean Grey",
            account_type=Client.REGULAR,
            registered_on=date.today(),
        )
        Client.objects.create(
            name="James Bond",
            account_type=Client.PLATINUM,
            registered_on=date.today(),
        )
        Client.objects.create(
            name="Jane Porter",
            account_type=Client.PLATINUM,
            registered_on=date.today(),
        )
        self.assertEqual(
            Client.objects.aggregate(
                regular=Count("pk", filter=Q(account_type=Client.REGULAR)),
                gold=Count("pk", filter=Q(account_type=Client.GOLD)),
                platinum=Count("pk", filter=Q(account_type=Client.PLATINUM)),
            ),
            {"regular": 2, "gold": 1, "platinum": 3},
        )
        # This was the example before the filter argument was added.
        self.assertEqual(
            Client.objects.aggregate(
                regular=Sum(
                    Case(
                        When(account_type=Client.REGULAR, then=1),
                    )
                ),
                gold=Sum(
                    Case(
                        When(account_type=Client.GOLD, then=1),
                    )
                ),
                platinum=Sum(
                    Case(
                        When(account_type=Client.PLATINUM, then=1),
                    )
                ),
            ),
            {"regular": 2, "gold": 1, "platinum": 3},
        )

    def test_filter_example(self):
        a_month_ago = date.today() - timedelta(days=30)
        a_year_ago = date.today() - timedelta(days=365)
        self.assertQuerysetEqual(
            Client.objects.filter(
                registered_on__lte=Case(
                    When(account_type=Client.GOLD, then=a_month_ago),
                    When(account_type=Client.PLATINUM, then=a_year_ago),
                ),
            ),
            [("Jack Black", "P")],
            transform=attrgetter("name", "account_type"),
        )

    def test_hash(self):
        expression_1 = Case(
            When(account_type__in=[Client.REGULAR, Client.GOLD], then=1),
            default=2,
            output_field=IntegerField(),
        )
        expression_2 = Case(
            When(account_type__in=(Client.REGULAR, Client.GOLD), then=1),
            default=2,
            output_field=IntegerField(),
        )
        expression_3 = Case(
            When(account_type__in=[Client.REGULAR, Client.GOLD], then=1), default=2
        )
        expression_4 = Case(
            When(account_type__in=[Client.PLATINUM, Client.GOLD], then=2), default=1
        )
        self.assertEqual(hash(expression_1), hash(expression_2))
        self.assertNotEqual(hash(expression_2), hash(expression_3))
        self.assertNotEqual(hash(expression_1), hash(expression_4))
        self.assertNotEqual(hash(expression_3), hash(expression_4))


class CaseWhenTests(SimpleTestCase):
    def test_only_when_arguments(self):
        msg = "Positional arguments must all be When objects."
        with self.assertRaisesMessage(TypeError, msg):
            Case(When(Q(pk__in=[])), object())

    def test_invalid_when_constructor_args(self):
        msg = (
            "When() supports a Q object, a boolean expression, or lookups as "
            "a condition."
        )
        with self.assertRaisesMessage(TypeError, msg):
            When(condition=object())
        with self.assertRaisesMessage(TypeError, msg):
            When(condition=Value(1))
        with self.assertRaisesMessage(TypeError, msg):
            When(Value(1), string="1")
        with self.assertRaisesMessage(TypeError, msg):
            When()

    def test_empty_q_object(self):
        msg = "An empty Q() can't be used as a When() condition."
        with self.assertRaisesMessage(ValueError, msg):
            When(Q(), then=Value(True))