cpython/Lib/test/test_enumerate.py
Guido van Rossum 97c1adf393 Anti-registration of various ABC methods.
- Issue #25958: Support "anti-registration" of special methods from
  various ABCs, like __hash__, __iter__ or __len__.  All these (and
  several more) can be set to None in an implementation class and the
  behavior will be as if the method is not defined at all.
  (Previously, this mechanism existed only for __hash__, to make
  mutable classes unhashable.)  Code contributed by Andrew Barnert and
  Ivan Levkivskyi.
2016-08-18 09:22:23 -07:00

270 lines
7.9 KiB
Python

import unittest
import operator
import sys
import pickle
from test import support
class G:
'Sequence using __getitem__'
def __init__(self, seqn):
self.seqn = seqn
def __getitem__(self, i):
return self.seqn[i]
class I:
'Sequence using iterator protocol'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __iter__(self):
return self
def __next__(self):
if self.i >= len(self.seqn): raise StopIteration
v = self.seqn[self.i]
self.i += 1
return v
class Ig:
'Sequence using iterator protocol defined with a generator'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __iter__(self):
for val in self.seqn:
yield val
class X:
'Missing __getitem__ and __iter__'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __next__(self):
if self.i >= len(self.seqn): raise StopIteration
v = self.seqn[self.i]
self.i += 1
return v
class E:
'Test propagation of exceptions'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __iter__(self):
return self
def __next__(self):
3 // 0
class N:
'Iterator missing __next__()'
def __init__(self, seqn):
self.seqn = seqn
self.i = 0
def __iter__(self):
return self
class PickleTest:
# Helper to check picklability
def check_pickle(self, itorg, seq):
for proto in range(pickle.HIGHEST_PROTOCOL + 1):
d = pickle.dumps(itorg, proto)
it = pickle.loads(d)
self.assertEqual(type(itorg), type(it))
self.assertEqual(list(it), seq)
it = pickle.loads(d)
try:
next(it)
except StopIteration:
self.assertFalse(seq[1:])
continue
d = pickle.dumps(it, proto)
it = pickle.loads(d)
self.assertEqual(list(it), seq[1:])
class EnumerateTestCase(unittest.TestCase, PickleTest):
enum = enumerate
seq, res = 'abc', [(0,'a'), (1,'b'), (2,'c')]
def test_basicfunction(self):
self.assertEqual(type(self.enum(self.seq)), self.enum)
e = self.enum(self.seq)
self.assertEqual(iter(e), e)
self.assertEqual(list(self.enum(self.seq)), self.res)
self.enum.__doc__
def test_pickle(self):
self.check_pickle(self.enum(self.seq), self.res)
def test_getitemseqn(self):
self.assertEqual(list(self.enum(G(self.seq))), self.res)
e = self.enum(G(''))
self.assertRaises(StopIteration, next, e)
def test_iteratorseqn(self):
self.assertEqual(list(self.enum(I(self.seq))), self.res)
e = self.enum(I(''))
self.assertRaises(StopIteration, next, e)
def test_iteratorgenerator(self):
self.assertEqual(list(self.enum(Ig(self.seq))), self.res)
e = self.enum(Ig(''))
self.assertRaises(StopIteration, next, e)
def test_noniterable(self):
self.assertRaises(TypeError, self.enum, X(self.seq))
def test_illformediterable(self):
self.assertRaises(TypeError, self.enum, N(self.seq))
def test_exception_propagation(self):
self.assertRaises(ZeroDivisionError, list, self.enum(E(self.seq)))
def test_argumentcheck(self):
self.assertRaises(TypeError, self.enum) # no arguments
self.assertRaises(TypeError, self.enum, 1) # wrong type (not iterable)
self.assertRaises(TypeError, self.enum, 'abc', 'a') # wrong type
self.assertRaises(TypeError, self.enum, 'abc', 2, 3) # too many arguments
@support.cpython_only
def test_tuple_reuse(self):
# Tests an implementation detail where tuple is reused
# whenever nothing else holds a reference to it
self.assertEqual(len(set(map(id, list(enumerate(self.seq))))), len(self.seq))
self.assertEqual(len(set(map(id, enumerate(self.seq)))), min(1,len(self.seq)))
class MyEnum(enumerate):
pass
class SubclassTestCase(EnumerateTestCase):
enum = MyEnum
class TestEmpty(EnumerateTestCase):
seq, res = '', []
class TestBig(EnumerateTestCase):
seq = range(10,20000,2)
res = list(zip(range(20000), seq))
class TestReversed(unittest.TestCase, PickleTest):
def test_simple(self):
class A:
def __getitem__(self, i):
if i < 5:
return str(i)
raise StopIteration
def __len__(self):
return 5
for data in 'abc', range(5), tuple(enumerate('abc')), A(), range(1,17,5):
self.assertEqual(list(data)[::-1], list(reversed(data)))
self.assertRaises(TypeError, reversed, {})
# don't allow keyword arguments
self.assertRaises(TypeError, reversed, [], a=1)
def test_range_optimization(self):
x = range(1)
self.assertEqual(type(reversed(x)), type(iter(x)))
def test_len(self):
for s in ('hello', tuple('hello'), list('hello'), range(5)):
self.assertEqual(operator.length_hint(reversed(s)), len(s))
r = reversed(s)
list(r)
self.assertEqual(operator.length_hint(r), 0)
class SeqWithWeirdLen:
called = False
def __len__(self):
if not self.called:
self.called = True
return 10
raise ZeroDivisionError
def __getitem__(self, index):
return index
r = reversed(SeqWithWeirdLen())
self.assertRaises(ZeroDivisionError, operator.length_hint, r)
def test_gc(self):
class Seq:
def __len__(self):
return 10
def __getitem__(self, index):
return index
s = Seq()
r = reversed(s)
s.r = r
def test_args(self):
self.assertRaises(TypeError, reversed)
self.assertRaises(TypeError, reversed, [], 'extra')
@unittest.skipUnless(hasattr(sys, 'getrefcount'), 'test needs sys.getrefcount()')
def test_bug1229429(self):
# this bug was never in reversed, it was in
# PyObject_CallMethod, and reversed_new calls that sometimes.
def f():
pass
r = f.__reversed__ = object()
rc = sys.getrefcount(r)
for i in range(10):
try:
reversed(f)
except TypeError:
pass
else:
self.fail("non-callable __reversed__ didn't raise!")
self.assertEqual(rc, sys.getrefcount(r))
def test_objmethods(self):
# Objects must have __len__() and __getitem__() implemented.
class NoLen(object):
def __getitem__(self, i): return 1
nl = NoLen()
self.assertRaises(TypeError, reversed, nl)
class NoGetItem(object):
def __len__(self): return 2
ngi = NoGetItem()
self.assertRaises(TypeError, reversed, ngi)
class Blocked(object):
def __getitem__(self, i): return 1
def __len__(self): return 2
__reversed__ = None
b = Blocked()
self.assertRaises(TypeError, reversed, b)
def test_pickle(self):
for data in 'abc', range(5), tuple(enumerate('abc')), range(1,17,5):
self.check_pickle(reversed(data), list(data)[::-1])
class EnumerateStartTestCase(EnumerateTestCase):
def test_basicfunction(self):
e = self.enum(self.seq)
self.assertEqual(iter(e), e)
self.assertEqual(list(self.enum(self.seq)), self.res)
class TestStart(EnumerateStartTestCase):
enum = lambda self, i: enumerate(i, start=11)
seq, res = 'abc', [(11, 'a'), (12, 'b'), (13, 'c')]
class TestLongStart(EnumerateStartTestCase):
enum = lambda self, i: enumerate(i, start=sys.maxsize+1)
seq, res = 'abc', [(sys.maxsize+1,'a'), (sys.maxsize+2,'b'),
(sys.maxsize+3,'c')]
if __name__ == "__main__":
unittest.main()