from django.db.models import IntegerField, Value

from django.db.models.functions import Lower, Right

from django.test import TestCase

from ..models import Author

class RightTests(TestCase):

    @classmethod

    def setUpTestData(cls):

        Author.objects.create(name="John Smith", alias="smithj")

        Author.objects.create(name="Rhonda")

    def test_basic(self):

        authors = Author.objects.annotate(name_part=Right("name", 5))

        self.assertQuerysetEqual(

            authors.order_by("name"), ["Smith", "honda"], lambda a: a.name_part

        )

        # If alias is null, set it to the first 2 lower characters of the name.

        Author.objects.filter(alias__isnull=True).update(alias=Lower(Right("name", 2)))

        self.assertQuerysetEqual(

            authors.order_by("name"), ["smithj", "da"], lambda a: a.alias

        )

    def test_invalid_length(self):

        with self.assertRaisesMessage(ValueError, "'length' must be greater than 0"):

            Author.objects.annotate(raises=Right("name", 0))

    def test_expressions(self):

        authors = Author.objects.annotate(

            name_part=Right("name", Value(3, output_field=IntegerField()))

        )

        self.assertQuerysetEqual(

            authors.order_by("name"), ["ith", "nda"], lambda a: a.name_part

        )