from django.db.models import F, Sum

from django.test import TestCase

from .models import Product, Stock

class DecimalFieldLookupTests(TestCase):

    @classmethod

    def setUpTestData(cls):

        cls.p1 = Product.objects.create(name="Product1", qty_target=10)

        Stock.objects.create(product=cls.p1, qty_available=5)

        Stock.objects.create(product=cls.p1, qty_available=6)

        cls.p2 = Product.objects.create(name="Product2", qty_target=10)

        Stock.objects.create(product=cls.p2, qty_available=5)

        Stock.objects.create(product=cls.p2, qty_available=5)

        cls.p3 = Product.objects.create(name="Product3", qty_target=10)

        Stock.objects.create(product=cls.p3, qty_available=5)

        Stock.objects.create(product=cls.p3, qty_available=4)

        cls.queryset = Product.objects.annotate(

            qty_available_sum=Sum("stock__qty_available"),

        ).annotate(qty_needed=F("qty_target") - F("qty_available_sum"))

    def test_gt(self):

        qs = self.queryset.filter(qty_needed__gt=0)

        self.assertCountEqual(qs, [self.p3])

    def test_gte(self):

        qs = self.queryset.filter(qty_needed__gte=0)

        self.assertCountEqual(qs, [self.p2, self.p3])

    def test_lt(self):

        qs = self.queryset.filter(qty_needed__lt=0)

        self.assertCountEqual(qs, [self.p1])

    def test_lte(self):

        qs = self.queryset.filter(qty_needed__lte=0)

        self.assertCountEqual(qs, [self.p1, self.p2])