# Test iterators.
import unittest
from test.test_support import run_unittest, TESTFN, unlink, have_unicode, \
check_py3k_warnings, cpython_only
# Test result of triple loop (too big to inline)
TRIPLETS = [(0, 0, 0), (0, 0, 1), (0, 0, 2),
(0, 1, 0), (0, 1, 1), (0, 1, 2),
(0, 2, 0), (0, 2, 1), (0, 2, 2),
(1, 0, 0), (1, 0, 1), (1, 0, 2),
(1, 1, 0), (1, 1, 1), (1, 1, 2),
(1, 2, 0), (1, 2, 1), (1, 2, 2),
(2, 0, 0), (2, 0, 1), (2, 0, 2),
(2, 1, 0), (2, 1, 1), (2, 1, 2),
(2, 2, 0), (2, 2, 1), (2, 2, 2)]
# Helper classes
class BasicIterClass:
def __init__(self, n):
self.n = n
self.i = 0
def next(self):
res = self.i
if res >= self.n:
raise StopIteration
self.i = res + 1
return res
class IteratingSequenceClass:
def __init__(self, n):
self.n = n
def __iter__(self):
return BasicIterClass(self.n)
class SequenceClass:
def __init__(self, n):
self.n = n
def __getitem__(self, i):
if 0 <= i < self.n:
return i
else:
raise IndexError
# Main test suite
class TestCase(unittest.TestCase):
# Helper to check that an iterator returns a given sequence
def check_iterator(self, it, seq):
res = []
while 1:
try:
val = it.next()
except StopIteration:
break
res.append(val)
self.assertEqual(res, seq)
# Helper to check that a for loop generates a given sequence
def check_for_loop(self, expr, seq):
res = []
for val in expr:
res.append(val)
self.assertEqual(res, seq)
# Test basic use of iter() function
def test_iter_basic(self):
self.check_iterator(iter(range(10)), range(10))
# Test that iter(iter(x)) is the same as iter(x)
def test_iter_idempotency(self):
seq = range(10)
it = iter(seq)
it2 = iter(it)
self.assertTrue(it is it2)
# Test that for loops over iterators work
def test_iter_for_loop(self):
self.check_for_loop(iter(range(10)), range(10))
# Test several independent iterators over the same list
def test_iter_independence(self):
seq = range(3)
res = []
for i in iter(seq):
for j in iter(seq):
for k in iter(seq):
res.append((i, j, k))
self.assertEqual(res, TRIPLETS)
# Test triple list comprehension using iterators
def test_nested_comprehensions_iter(self):
seq = range(3)
res = [(i, j, k)
for i in iter(seq) for j in iter(seq) for k in iter(seq)]
self.assertEqual(res, TRIPLETS)
# Test triple list comprehension without iterators
def test_nested_comprehensions_for(self):
seq = range(3)
res = [(i, j, k) for i in seq for j in seq for k in seq]
self.assertEqual(res, TRIPLETS)
# Test a class with __iter__ in a for loop
def test_iter_class_for(self):
self.check_for_loop(IteratingSequenceClass(10), range(10))
# Test a class with __iter__ with explicit iter()
def test_iter_class_iter(self):
self.check_iterator(iter(IteratingSequenceClass(10)), range(10))
# Test for loop on a sequence class without __iter__
def test_seq_class_for(self):
self.check_for_loop(SequenceClass(10), range(10))
# Test iter() on a sequence class without __iter__
def test_seq_class_iter(self):
self.check_iterator(iter(SequenceClass(10)), range(10))
# Test a new_style class with __iter__ but no next() method
def test_new_style_iter_class(self):
class IterClass(object):
def __iter__(self):
return self
self.assertRaises(TypeError, iter, IterClass())
# Test two-argument iter() with callable instance
def test_iter_callable(self):
class C:
def __init__(self):
self.i = 0
def __call__(self):
i = self.i
self.i = i + 1
if i > 100:
raise IndexError # Emergency stop
return i
self.check_iterator(iter(C(), 10), range(10))
# Test two-argument iter() with function
def test_iter_function(self):
def spam(state=[0]):
i = state[0]
state[0] = i+1
return i
self.check_iterator(iter(spam, 10), range(10))
# Test two-argument iter() with function that raises StopIteration
def test_iter_function_stop(self):
def spam(state=[0]):
i = state[0]
if i == 10:
raise StopIteration
state[0] = i+1
return i
self.check_iterator(iter(spam, 20), range(10))
# Test exception propagation through function iterator
def test_exception_function(self):
def spam(state=[0]):
i = state[0]
state[0] = i+1
if i == 10:
raise RuntimeError
return i
res = []
try:
for x in iter(spam, 20):
res.append(x)
except RuntimeError:
self.assertEqual(res, range(10))
else:
self.fail("should have raised RuntimeError")
# Test exception propagation through sequence iterator
def test_exception_sequence(self):
class MySequenceClass(SequenceClass):
def __getitem__(self, i):
if i == 10:
raise RuntimeError
return SequenceClass.__getitem__(self, i)
res = []
try:
for x in MySequenceClass(20):
res.append(x)
except RuntimeError:
self.assertEqual(res, range(10))
else:
self.fail("should have raised RuntimeError")
# Test for StopIteration from __getitem__
def test_stop_sequence(self):
class MySequenceClass(SequenceClass):
def __getitem__(self, i):
if i == 10:
raise StopIteration
return SequenceClass.__getitem__(self, i)
self.check_for_loop(MySequenceClass(20), range(10))
# Test a big range
def test_iter_big_range(self):
self.check_for_loop(iter(range(10000)), range(10000))
# Test an empty list
def test_iter_empty(self):
self.check_for_loop(iter([]), [])
# Test a tuple
def test_iter_tuple(self):
self.check_for_loop(iter((0,1,2,3,4,5,6,7,8,9)), range(10))
# Test an xrange
def test_iter_xrange(self):
self.check_for_loop(iter(xrange(10)), range(10))
# Test a string
def test_iter_string(self):
self.check_for_loop(iter("abcde"), ["a", "b", "c", "d", "e"])
# Test a Unicode string
if have_unicode:
def test_iter_unicode(self):
self.check_for_loop(iter(unicode("abcde")),
[unicode("a"), unicode("b"), unicode("c"),
unicode("d"), unicode("e")])
# Test a directory
def test_iter_dict(self):
dict = {}
for i in range(10):
dict[i] = None
self.check_for_loop(dict, dict.keys())
# Test a file
def test_iter_file(self):
f = open(TESTFN, "w")
try:
for i in range(5):
f.write("%d\n" % i)
finally:
f.close()
f = open(TESTFN, "r")
try:
self.check_for_loop(f, ["0\n", "1\n", "2\n", "3\n", "4\n"])
self.check_for_loop(f, [])
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
# Test list()'s use of iterators.
def test_builtin_list(self):
self.assertEqual(list(SequenceClass(5)), range(5))
self.assertEqual(list(SequenceClass(0)), [])
self.assertEqual(list(()), [])
self.assertEqual(list(range(10, -1, -1)), range(10, -1, -1))
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(list(d), d.keys())
self.assertRaises(TypeError, list, list)
self.assertRaises(TypeError, list, 42)
f = open(TESTFN, "w")
try:
for i in range(5):
f.write("%d\n" % i)
finally:
f.close()
f = open(TESTFN, "r")
try:
self.assertEqual(list(f), ["0\n", "1\n", "2\n", "3\n", "4\n"])
f.seek(0, 0)
self.assertEqual(list(f),
["0\n", "1\n", "2\n", "3\n", "4\n"])
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
# Test tuples()'s use of iterators.
def test_builtin_tuple(self):
self.assertEqual(tuple(SequenceClass(5)), (0, 1, 2, 3, 4))
self.assertEqual(tuple(SequenceClass(0)), ())
self.assertEqual(tuple([]), ())
self.assertEqual(tuple(()), ())
self.assertEqual(tuple("abc"), ("a", "b", "c"))
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(tuple(d), tuple(d.keys()))
self.assertRaises(TypeError, tuple, list)
self.assertRaises(TypeError, tuple, 42)
f = open(TESTFN, "w")
try:
for i in range(5):
f.write("%d\n" % i)
finally:
f.close()
f = open(TESTFN, "r")
try:
self.assertEqual(tuple(f), ("0\n", "1\n", "2\n", "3\n", "4\n"))
f.seek(0, 0)
self.assertEqual(tuple(f),
("0\n", "1\n", "2\n", "3\n", "4\n"))
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
# Test filter()'s use of iterators.
def test_builtin_filter(self):
self.assertEqual(filter(None, SequenceClass(5)), range(1, 5))
self.assertEqual(filter(None, SequenceClass(0)), [])
self.assertEqual(filter(None, ()), ())
self.assertEqual(filter(None, "abc"), "abc")
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(filter(None, d), d.keys())
self.assertRaises(TypeError, filter, None, list)
self.assertRaises(TypeError, filter, None, 42)
class Boolean:
def __init__(self, truth):
self.truth = truth
def __nonzero__(self):
return self.truth
bTrue = Boolean(1)
bFalse = Boolean(0)
class Seq:
def __init__(self, *args):
self.vals = args
def __iter__(self):
class SeqIter:
def __init__(self, vals):
self.vals = vals
self.i = 0
def __iter__(self):
return self
def next(self):
i = self.i
self.i = i + 1
if i < len(self.vals):
return self.vals[i]
else:
raise StopIteration
return SeqIter(self.vals)
seq = Seq(*([bTrue, bFalse] * 25))
self.assertEqual(filter(lambda x: not x, seq), [bFalse]*25)
self.assertEqual(filter(lambda x: not x, iter(seq)), [bFalse]*25)
# Test max() and min()'s use of iterators.
def test_builtin_max_min(self):
self.assertEqual(max(SequenceClass(5)), 4)
self.assertEqual(min(SequenceClass(5)), 0)
self.assertEqual(max(8, -1), 8)
self.assertEqual(min(8, -1), -1)
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(max(d), "two")
self.assertEqual(min(d), "one")
self.assertEqual(max(d.itervalues()), 3)
self.assertEqual(min(iter(d.itervalues())), 1)
f = open(TESTFN, "w")
try:
f.write("medium line\n")
f.write("xtra large line\n")
f.write("itty-bitty line\n")
finally:
f.close()
f = open(TESTFN, "r")
try:
self.assertEqual(min(f), "itty-bitty line\n")
f.seek(0, 0)
self.assertEqual(max(f), "xtra large line\n")
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
# Test map()'s use of iterators.
def test_builtin_map(self):
self.assertEqual(map(lambda x: x+1, SequenceClass(5)), range(1, 6))
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(map(lambda k, d=d: (k, d[k]), d), d.items())
dkeys = d.keys()
expected = [(i < len(d) and dkeys[i] or None,
i,
i < len(d) and dkeys[i] or None)
for i in range(5)]
# Deprecated map(None, ...)
with check_py3k_warnings():
self.assertEqual(map(None, SequenceClass(5)), range(5))
self.assertEqual(map(None, d), d.keys())
self.assertEqual(map(None, d,
SequenceClass(5),
iter(d.iterkeys())),
expected)
f = open(TESTFN, "w")
try:
for i in range(10):
f.write("xy" * i + "\n") # line i has len 2*i+1
finally:
f.close()
f = open(TESTFN, "r")
try:
self.assertEqual(map(len, f), range(1, 21, 2))
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
# Test zip()'s use of iterators.
def test_builtin_zip(self):
self.assertEqual(zip(), [])
self.assertEqual(zip(*[]), [])
self.assertEqual(zip(*[(1, 2), 'ab']), [(1, 'a'), (2, 'b')])
self.assertRaises(TypeError, zip, None)
self.assertRaises(TypeError, zip, range(10), 42)
self.assertRaises(TypeError, zip, range(10), zip)
self.assertEqual(zip(IteratingSequenceClass(3)),
[(0,), (1,), (2,)])
self.assertEqual(zip(SequenceClass(3)),
[(0,), (1,), (2,)])
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(d.items(), zip(d, d.itervalues()))
# Generate all ints starting at constructor arg.
class IntsFrom:
def __init__(self, start):
self.i = start
def __iter__(self):
return self
def next(self):
i = self.i
self.i = i+1
return i
f = open(TESTFN, "w")
try:
f.write("a\n" "bbb\n" "cc\n")
finally:
f.close()
f = open(TESTFN, "r")
try:
self.assertEqual(zip(IntsFrom(0), f, IntsFrom(-100)),
[(0, "a\n", -100),
(1, "bbb\n", -99),
(2, "cc\n", -98)])
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
self.assertEqual(zip(xrange(5)), [(i,) for i in range(5)])
# Classes that lie about their lengths.
class NoGuessLen5:
def __getitem__(self, i):
if i >= 5:
raise IndexError
return i
class Guess3Len5(NoGuessLen5):
def __len__(self):
return 3
class Guess30Len5(NoGuessLen5):
def __len__(self):
return 30
self.assertEqual(len(Guess3Len5()), 3)
self.assertEqual(len(Guess30Len5()), 30)
self.assertEqual(zip(NoGuessLen5()), zip(range(5)))
self.assertEqual(zip(Guess3Len5()), zip(range(5)))
self.assertEqual(zip(Guess30Len5()), zip(range(5)))
expected = [(i, i) for i in range(5)]
for x in NoGuessLen5(), Guess3Len5(), Guess30Len5():
for y in NoGuessLen5(), Guess3Len5(), Guess30Len5():
self.assertEqual(zip(x, y), expected)
# Test reduces()'s use of iterators.
def test_deprecated_builtin_reduce(self):
with check_py3k_warnings():
self._test_builtin_reduce()
def _test_builtin_reduce(self):
from operator import add
self.assertEqual(reduce(add, SequenceClass(5)), 10)
self.assertEqual(reduce(add, SequenceClass(5), 42), 52)
self.assertRaises(TypeError, reduce, add, SequenceClass(0))
self.assertEqual(reduce(add, SequenceClass(0), 42), 42)
self.assertEqual(reduce(add, SequenceClass(1)), 0)
self.assertEqual(reduce(add, SequenceClass(1), 42), 42)
d = {"one": 1, "two": 2, "three": 3}
self.assertEqual(reduce(add, d), "".join(d.keys()))
# This test case will be removed if we don't have Unicode
def test_unicode_join_endcase(self):
# This class inserts a Unicode object into its argument's natural
# iteration, in the 3rd position.
class OhPhooey:
def __init__(self, seq):
self.it = iter(seq)
self.i = 0
def __iter__(self):
return self
def next(self):
i = self.i
self.i = i+1
if i == 2:
return unicode("fooled you!")
return self.it.next()
f = open(TESTFN, "w")
try:
f.write("a\n" + "b\n" + "c\n")
finally:
f.close()
f = open(TESTFN, "r")
# Nasty: string.join(s) can't know whether unicode.join() is needed
# until it's seen all of s's elements. But in this case, f's
# iterator cannot be restarted. So what we're testing here is
# whether string.join() can manage to remember everything it's seen
# and pass that on to unicode.join().
try:
got = " - ".join(OhPhooey(f))
self.assertEqual(got, unicode("a\n - b\n - fooled you! - c\n"))
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
if not have_unicode:
def test_unicode_join_endcase(self): pass
# Test iterators with 'x in y' and 'x not in y'.
def test_in_and_not_in(self):
for sc5 in IteratingSequenceClass(5), SequenceClass(5):
for i in range(5):
self.assertIn(i, sc5)
for i in "abc", -1, 5, 42.42, (3, 4), [], {1: 1}, 3-12j, sc5:
self.assertNotIn(i, sc5)
self.assertRaises(TypeError, lambda: 3 in 12)
self.assertRaises(TypeError, lambda: 3 not in map)
d = {"one": 1, "two": 2, "three": 3, 1j: 2j}
for k in d:
self.assertIn(k, d)
self.assertNotIn(k, d.itervalues())
for v in d.values():
self.assertIn(v, d.itervalues())
self.assertNotIn(v, d)
for k, v in d.iteritems():
self.assertIn((k, v), d.iteritems())
self.assertNotIn((v, k), d.iteritems())
f = open(TESTFN, "w")
try:
f.write("a\n" "b\n" "c\n")
finally:
f.close()
f = open(TESTFN, "r")
try:
for chunk in "abc":
f.seek(0, 0)
self.assertNotIn(chunk, f)
f.seek(0, 0)
self.assertIn((chunk + "\n"), f)
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
# Test iterators with operator.countOf (PySequence_Count).
def test_countOf(self):
from operator import countOf
self.assertEqual(countOf([1,2,2,3,2,5], 2), 3)
self.assertEqual(countOf((1,2,2,3,2,5), 2), 3)
self.assertEqual(countOf("122325", "2"), 3)
self.assertEqual(countOf("122325", "6"), 0)
self.assertRaises(TypeError, countOf, 42, 1)
self.assertRaises(TypeError, countOf, countOf, countOf)
d = {"one": 3, "two": 3, "three": 3, 1j: 2j}
for k in d:
self.assertEqual(countOf(d, k), 1)
self.assertEqual(countOf(d.itervalues(), 3), 3)
self.assertEqual(countOf(d.itervalues(), 2j), 1)
self.assertEqual(countOf(d.itervalues(), 1j), 0)
f = open(TESTFN, "w")
try:
f.write("a\n" "b\n" "c\n" "b\n")
finally:
f.close()
f = open(TESTFN, "r")
try:
for letter, count in ("a", 1), ("b", 2), ("c", 1), ("d", 0):
f.seek(0, 0)
self.assertEqual(countOf(f, letter + "\n"), count)
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
# Test iterators with operator.indexOf (PySequence_Index).
def test_indexOf(self):
from operator import indexOf
self.assertEqual(indexOf([1,2,2,3,2,5], 1), 0)
self.assertEqual(indexOf((1,2,2,3,2,5), 2), 1)
self.assertEqual(indexOf((1,2,2,3,2,5), 3), 3)
self.assertEqual(indexOf((1,2,2,3,2,5), 5), 5)
self.assertRaises(ValueError, indexOf, (1,2,2,3,2,5), 0)
self.assertRaises(ValueError, indexOf, (1,2,2,3,2,5), 6)
self.assertEqual(indexOf("122325", "2"), 1)
self.assertEqual(indexOf("122325", "5"), 5)
self.assertRaises(ValueError, indexOf, "122325", "6")
self.assertRaises(TypeError, indexOf, 42, 1)
self.assertRaises(TypeError, indexOf, indexOf, indexOf)
f = open(TESTFN, "w")
try:
f.write("a\n" "b\n" "c\n" "d\n" "e\n")
finally:
f.close()
f = open(TESTFN, "r")
try:
fiter = iter(f)
self.assertEqual(indexOf(fiter, "b\n"), 1)
self.assertEqual(indexOf(fiter, "d\n"), 1)
self.assertEqual(indexOf(fiter, "e\n"), 0)
self.assertRaises(ValueError, indexOf, fiter, "a\n")
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
iclass = IteratingSequenceClass(3)
for i in range(3):
self.assertEqual(indexOf(iclass, i), i)
self.assertRaises(ValueError, indexOf, iclass, -1)
# Test iterators with file.writelines().
def test_writelines(self):
f = file(TESTFN, "w")
try:
self.assertRaises(TypeError, f.writelines, None)
self.assertRaises(TypeError, f.writelines, 42)
f.writelines(["1\n", "2\n"])
f.writelines(("3\n", "4\n"))
f.writelines({'5\n': None})
f.writelines({})
# Try a big chunk too.
class Iterator:
def __init__(self, start, finish):
self.start = start
self.finish = finish
self.i = self.start
def next(self):
if self.i >= self.finish:
raise StopIteration
result = str(self.i) + '\n'
self.i += 1
return result
def __iter__(self):
return self
class Whatever:
def __init__(self, start, finish):
self.start = start
self.finish = finish
def __iter__(self):
return Iterator(self.start, self.finish)
f.writelines(Whatever(6, 6+2000))
f.close()
f = file(TESTFN)
expected = [str(i) + "\n" for i in range(1, 2006)]
self.assertEqual(list(f), expected)
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
# Test iterators on RHS of unpacking assignments.
def test_unpack_iter(self):
a, b = 1, 2
self.assertEqual((a, b), (1, 2))
a, b, c = IteratingSequenceClass(3)
self.assertEqual((a, b, c), (0, 1, 2))
try: # too many values
a, b = IteratingSequenceClass(3)
except ValueError:
pass
else:
self.fail("should have raised ValueError")
try: # not enough values
a, b, c = IteratingSequenceClass(2)
except ValueError:
pass
else:
self.fail("should have raised ValueError")
try: # not iterable
a, b, c = len
except TypeError:
pass
else:
self.fail("should have raised TypeError")
a, b, c = {1: 42, 2: 42, 3: 42}.itervalues()
self.assertEqual((a, b, c), (42, 42, 42))
f = open(TESTFN, "w")
lines = ("a\n", "bb\n", "ccc\n")
try:
for line in lines:
f.write(line)
finally:
f.close()
f = open(TESTFN, "r")
try:
a, b, c = f
self.assertEqual((a, b, c), lines)
finally:
f.close()
try:
unlink(TESTFN)
except OSError:
pass
(a, b), (c,) = IteratingSequenceClass(2), {42: 24}
self.assertEqual((a, b, c), (0, 1, 42))
@cpython_only
def test_ref_counting_behavior(self):
class C(object):
count = 0
def __new__(cls):
cls.count += 1
return object.__new__(cls)
def __del__(self):
cls = self.__class__
assert cls.count > 0
cls.count -= 1
x = C()
self.assertEqual(C.count, 1)
del x
self.assertEqual(C.count, 0)
l = [C(), C(), C()]
self.assertEqual(C.count, 3)
try:
a, b = iter(l)
except ValueError:
pass
del l
self.assertEqual(C.count, 0)
# Make sure StopIteration is a "sink state".
# This tests various things that weren't sink states in Python 2.2.1,
# plus various things that always were fine.
def test_sinkstate_list(self):
# This used to fail
a = range(5)
b = iter(a)
self.assertEqual(list(b), range(5))
a.extend(range(5, 10))
self.assertEqual(list(b), [])
def test_sinkstate_tuple(self):
a = (0, 1, 2, 3, 4)
b = iter(a)
self.assertEqual(list(b), range(5))
self.assertEqual(list(b), [])
def test_sinkstate_string(self):
a = "abcde"
b = iter(a)
self.assertEqual(list(b), ['a', 'b', 'c', 'd', 'e'])
self.assertEqual(list(b), [])
def test_sinkstate_sequence(self):
# This used to fail
a = SequenceClass(5)
b = iter(a)
self.assertEqual(list(b), range(5))
a.n = 10
self.assertEqual(list(b), [])
def test_sinkstate_callable(self):
# This used to fail
def spam(state=[0]):
i = state[0]
state[0] = i+1
if i == 10:
raise AssertionError, "shouldn't have gotten this far"
return i
b = iter(spam, 5)
self.assertEqual(list(b), range(5))
self.assertEqual(list(b), [])
def test_sinkstate_dict(self):
# XXX For a more thorough test, see towards the end of:
# http://mail.python.org/pipermail/python-dev/2002-July/026512.html
a = {1:1, 2:2, 0:0, 4:4, 3:3}
for b in iter(a), a.iterkeys(), a.iteritems(), a.itervalues():
b = iter(a)
self.assertEqual(len(list(b)), 5)
self.assertEqual(list(b), [])
def test_sinkstate_yield(self):
def gen():
for i in range(5):
yield i
b = gen()
self.assertEqual(list(b), range(5))
self.assertEqual(list(b), [])
def test_sinkstate_range(self):
a = xrange(5)
b = iter(a)
self.assertEqual(list(b), range(5))
self.assertEqual(list(b), [])
def test_sinkstate_enumerate(self):
a = range(5)
e = enumerate(a)
b = iter(e)
self.assertEqual(list(b), zip(range(5), range(5)))
self.assertEqual(list(b), [])
def test_3720(self):
# Avoid a crash, when an iterator deletes its next() method.
class BadIterator(object):
def __iter__(self):
return self
def next(self):
del BadIterator.next
return 1
try:
for i in BadIterator() :
pass
except TypeError:
pass
def test_extending_list_with_iterator_does_not_segfault(self):
# The code to extend a list with an iterator has a fair
# amount of nontrivial logic in terms of guessing how
# much memory to allocate in advance, "stealing" refs,
# and then shrinking at the end. This is a basic smoke
# test for that scenario.
def gen():
for i in range(500):
yield i
lst = [0] * 500
for i in range(240):
lst.pop(0)
lst.extend(gen())
self.assertEqual(len(lst), 760)
def test_main():
run_unittest(TestCase)
if __name__ == "__main__":
test_main()