django/tests/db_functions/text/test_pad.py

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from django.db import connection
from django.db.models import Value
from django.db.models.functions import Length, LPad, RPad
from django.test import TestCase
2018-08-16 07:45:11 +08:00
from ..models import Author
class PadTests(TestCase):
def test_pad(self):
Author.objects.create(name="John", alias="j")
none_value = (
"" if connection.features.interprets_empty_strings_as_nulls else None
)
tests = (
(LPad("name", 7, Value("xy")), "xyxJohn"),
(RPad("name", 7, Value("xy")), "Johnxyx"),
(LPad("name", 6, Value("x")), "xxJohn"),
(RPad("name", 6, Value("x")), "Johnxx"),
# The default pad string is a space.
(LPad("name", 6), " John"),
(RPad("name", 6), "John "),
# If string is longer than length it is truncated.
(LPad("name", 2), "Jo"),
(RPad("name", 2), "Jo"),
(LPad("name", 0), ""),
(RPad("name", 0), ""),
(LPad("name", None), none_value),
(RPad("name", None), none_value),
(LPad(Value(None), 1), none_value),
(RPad(Value(None), 1), none_value),
(LPad("goes_by", 1), none_value),
(RPad("goes_by", 1), none_value),
)
for function, padded_name in tests:
with self.subTest(function=function):
authors = Author.objects.annotate(padded_name=function)
self.assertQuerysetEqual(
authors, [padded_name], lambda a: a.padded_name, ordered=False
)
def test_pad_negative_length(self):
for function in (LPad, RPad):
with self.subTest(function=function):
with self.assertRaisesMessage(
ValueError, "'length' must be greater or equal to 0."
):
function("name", -1)
def test_combined_with_length(self):
Author.objects.create(name="Rhonda", alias="john_smith")
Author.objects.create(name="♥♣♠", alias="bytes")
authors = Author.objects.annotate(filled=LPad("name", Length("alias")))
self.assertQuerysetEqual(
authors.order_by("alias"),
[" ♥♣♠", " Rhonda"],
lambda a: a.filled,
)