django/tests/utils_tests/test_simplelazyobject.py

from __future__ import unicode_literals

import copy
import pickle
import sys
from unittest import TestCase

from django.utils import six
from django.utils.functional import SimpleLazyObject, empty


class _ComplexObject(object):
    def __init__(self, name):
        self.name = name

    def __eq__(self, other):
        return self.name == other.name

    def __hash__(self):
        return hash(self.name)

    if six.PY3:
        def __bytes__(self):
            return ("I am _ComplexObject(%r)" % self.name).encode("utf-8")

        def __str__(self):
            return self.name

    else:
        def __str__(self):
            return b"I am _ComplexObject(%r)" % str(self.name)

        def __unicode__(self):
            return self.name

    def __repr__(self):
        return "_ComplexObject(%r)" % self.name


complex_object = lambda: _ComplexObject("joe")


class TestUtilsSimpleLazyObject(TestCase):
    """
    Tests for SimpleLazyObject
    """
    # Note that concrete use cases for SimpleLazyObject are also found in the
    # auth context processor tests (unless the implementation of that function
    # is changed).

    def test_equality(self):
        self.assertEqual(complex_object(), SimpleLazyObject(complex_object))
        self.assertEqual(SimpleLazyObject(complex_object), complex_object())

    def test_hash(self):
        # hash() equality would not be true for many objects, but it should be
        # for _ComplexObject
        self.assertEqual(hash(complex_object()),
                         hash(SimpleLazyObject(complex_object)))

    def test_repr(self):
        # First, for an unevaluated SimpleLazyObject
        x = SimpleLazyObject(complex_object)
        # __repr__ contains __repr__ of setup function and does not evaluate
        # the SimpleLazyObject
        self.assertEqual("<SimpleLazyObject: %r>" % complex_object, repr(x))
        self.assertEqual(empty, x._wrapped)

        # Second, for an evaluated SimpleLazyObject
        name = x.name  # evaluate
        self.assertIsInstance(x._wrapped, _ComplexObject)
        # __repr__ contains __repr__ of wrapped object
        self.assertEqual("<SimpleLazyObject: %r>" % x._wrapped, repr(x))

    def test_bytes(self):
        self.assertEqual(b"I am _ComplexObject('joe')",
                bytes(SimpleLazyObject(complex_object)))

    def test_text(self):
        self.assertEqual("joe", six.text_type(SimpleLazyObject(complex_object)))

    def test_class(self):
        # This is important for classes that use __class__ in things like
        # equality tests.
        self.assertEqual(_ComplexObject, SimpleLazyObject(complex_object).__class__)

    def test_deepcopy(self):
        # Check that we *can* do deep copy, and that it returns the right
        # objects.

        # First, for an unevaluated SimpleLazyObject
        s = SimpleLazyObject(complex_object)
        self.assertIs(s._wrapped, empty)
        s2 = copy.deepcopy(s)
        # something has gone wrong is s is evaluated
        self.assertIs(s._wrapped, empty)
        self.assertEqual(s2, complex_object())

        # Second, for an evaluated SimpleLazyObject
        name = s.name  # evaluate
        self.assertIsNot(s._wrapped, empty)
        s3 = copy.deepcopy(s)
        self.assertEqual(s3, complex_object())

    def test_none(self):
        i = [0]

        def f():
            i[0] += 1
            return None

        x = SimpleLazyObject(f)
        self.assertEqual(str(x), "None")
        self.assertEqual(i, [1])
        self.assertEqual(str(x), "None")
        self.assertEqual(i, [1])

    def test_bool(self):
        x = SimpleLazyObject(lambda: 3)
        self.assertTrue(x)
        x = SimpleLazyObject(lambda: 0)
        self.assertFalse(x)

    def test_pickle_complex(self):
        # See ticket #16563
        x = SimpleLazyObject(complex_object)
        pickled = pickle.dumps(x)
        unpickled = pickle.loads(pickled)
        self.assertEqual(unpickled, x)
        self.assertEqual(six.text_type(unpickled), six.text_type(x))
        self.assertEqual(unpickled.name, x.name)

    def test_dict(self):
        # See ticket #18447
        lazydict = SimpleLazyObject(lambda: {'one': 1})
        self.assertEqual(lazydict['one'], 1)
        lazydict['one'] = -1
        self.assertEqual(lazydict['one'], -1)
        del lazydict['one']
        with self.assertRaises(KeyError):
            lazydict['one']

    def test_trace(self):
        # See ticket #19456
        old_trace_func = sys.gettrace()
        try:
            def trace_func(frame, event, arg):
                frame.f_locals['self'].__class__
                if old_trace_func is not None:
                    old_trace_func(frame, event, arg)
            sys.settrace(trace_func)
            SimpleLazyObject(None)
        finally:
            sys.settrace(old_trace_func)

    def test_not_equal(self):
        lazy1 = SimpleLazyObject(lambda: 2)
        lazy2 = SimpleLazyObject(lambda: 2)
        lazy3 = SimpleLazyObject(lambda: 3)
        self.assertEqual(lazy1, lazy2)
        self.assertNotEqual(lazy1, lazy3)
        self.assertTrue(lazy1 != lazy3)
        self.assertFalse(lazy1 != lazy2)

    def test_pickle_py2_regression(self):
        from django.contrib.auth.models import User

        # See ticket #20212
        user = User.objects.create_user('johndoe', 'john@example.com', 'pass')
        x = SimpleLazyObject(lambda: user)

        # This would fail with "TypeError: can't pickle instancemethod objects",
        # only on Python 2.X.
        pickled = pickle.dumps(x)

        # Try the variant protocol levels.
        pickled = pickle.dumps(x, 0)
        pickled = pickle.dumps(x, 1)
        pickled = pickle.dumps(x, 2)

        if not six.PY3:
            import cPickle

            # This would fail with "TypeError: expected string or Unicode object, NoneType found".
            pickled = cPickle.dumps(x)