Add test suite for iterators.
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Guido van Rossum
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test_iter
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# Test iterators.
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import unittest
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from test_support import run_unittest, TESTFN, unlink
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# Test result of triple loop (too big to inline)
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TRIPLETS = [(0, 0, 0), (0, 0, 1), (0, 0, 2),
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(0, 1, 0), (0, 1, 1), (0, 1, 2),
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(0, 2, 0), (0, 2, 1), (0, 2, 2),
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(1, 0, 0), (1, 0, 1), (1, 0, 2),
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(1, 1, 0), (1, 1, 1), (1, 1, 2),
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(1, 2, 0), (1, 2, 1), (1, 2, 2),
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(2, 0, 0), (2, 0, 1), (2, 0, 2),
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(2, 1, 0), (2, 1, 1), (2, 1, 2),
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(2, 2, 0), (2, 2, 1), (2, 2, 2)]
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# Helper classes
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class BasicIterClass:
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def __init__(self, n):
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self.n = n
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self.i = 0
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def next(self):
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res = self.i
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if res >= self.n:
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raise StopIteration
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self.i = res + 1
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return res
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class IteratingSequenceClass:
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def __init__(self, n):
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self.n = n
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def __iter__(self):
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return BasicIterClass(self.n)
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class SequenceClass:
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def __init__(self, n):
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self.n = n
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def __getitem__(self, i):
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if 0 <= i < self.n:
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return i
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else:
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raise IndexError
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# Main test suite
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class TestCase(unittest.TestCase):
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# Helper to check that an iterator returns a given sequence
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def check_iterator(self, it, seq):
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res = []
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while 1:
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try:
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val = it.next()
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except StopIteration:
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break
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res.append(val)
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self.assertEqual(res, seq)
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# Helper to check that a for loop generates a given sequence
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def check_for_loop(self, expr, seq):
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res = []
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for val in expr:
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res.append(val)
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self.assertEqual(res, seq)
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# Test basic use of iter() function
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def test_iter_basic(self):
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self.check_iterator(iter(range(10)), range(10))
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# Test that iter(iter(x)) is the same as iter(x)
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def test_iter_idempotency(self):
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seq = range(10)
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it = iter(seq)
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it2 = iter(it)
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self.assert_(it is it2)
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# Test that for loops over iterators work
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def test_iter_for_loop(self):
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self.check_for_loop(iter(range(10)), range(10))
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# Test several independent iterators over the same list
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def test_iter_independence(self):
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seq = range(3)
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res = []
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for i in iter(seq):
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for j in iter(seq):
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for k in iter(seq):
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res.append((i, j, k))
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self.assertEqual(res, TRIPLETS)
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# Test triple list comprehension using iterators
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def test_nested_comprehensions_iter(self):
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seq = range(3)
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res = [(i, j, k)
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for i in iter(seq) for j in iter(seq) for k in iter(seq)]
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self.assertEqual(res, TRIPLETS)
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# Test triple list comprehension without iterators
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def test_nested_comprehensions_for(self):
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seq = range(3)
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res = [(i, j, k) for i in seq for j in seq for k in seq]
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self.assertEqual(res, TRIPLETS)
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# Test a class with __iter__ in a for loop
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def test_iter_class_for(self):
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self.check_for_loop(IteratingSequenceClass(10), range(10))
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# Test a class with __iter__ with explicit iter()
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def test_iter_class_iter(self):
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self.check_iterator(iter(IteratingSequenceClass(10)), range(10))
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# Test for loop on a sequence class without __iter__
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def test_seq_class_for(self):
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self.check_for_loop(SequenceClass(10), range(10))
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# Test iter() on a sequence class without __iter__
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def test_seq_class_iter(self):
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self.check_iterator(iter(SequenceClass(10)), range(10))
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# Test two-argument iter() with callable instance
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def test_iter_callable(self):
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class C:
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def __init__(self):
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self.i = 0
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def __call__(self):
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i = self.i
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self.i = i + 1
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if i > 100:
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raise IndexError # Emergency stop
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return i
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self.check_iterator(iter(C(), 10), range(10))
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# Test two-argument iter() with function
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def test_iter_function(self):
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def spam(state=[0]):
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i = state[0]
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state[0] = i+1
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return i
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self.check_iterator(iter(spam, 10), range(10))
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# Test two-argument iter() with function that raises StopIteration
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def test_iter_function_stop(self):
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def spam(state=[0]):
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i = state[0]
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if i == 10:
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raise StopIteration
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state[0] = i+1
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return i
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self.check_iterator(iter(spam, 20), range(10))
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# Test exception propagation through function iterator
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def test_exception_function(self):
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def spam(state=[0]):
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i = state[0]
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state[0] = i+1
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if i == 10:
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raise RuntimeError
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return i
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res = []
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try:
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for x in iter(spam, 20):
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res.append(x)
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except RuntimeError:
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self.assertEqual(res, range(10))
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else:
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self.fail("should have raised RuntimeError")
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# Test exception propagation through sequence iterator
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def test_exception_sequence(self):
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class MySequenceClass(SequenceClass):
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def __getitem__(self, i):
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if i == 10:
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raise RuntimeError
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return SequenceClass.__getitem__(self, i)
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res = []
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try:
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for x in MySequenceClass(20):
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res.append(x)
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except RuntimeError:
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self.assertEqual(res, range(10))
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else:
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self.fail("should have raised RuntimeError")
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# Test for StopIteration from __getitem__
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def test_stop_sequence(self):
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class MySequenceClass(SequenceClass):
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def __getitem__(self, i):
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if i == 10:
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raise StopIteration
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return SequenceClass.__getitem__(self, i)
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self.check_for_loop(MySequenceClass(20), range(10))
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# Test a big range
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def test_iter_big_range(self):
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self.check_for_loop(iter(range(10000)), range(10000))
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# Test an empty list
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def test_iter_empty(self):
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self.check_for_loop(iter([]), [])
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# Test a tuple
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def test_iter_tuple(self):
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self.check_for_loop(iter((0,1,2,3,4,5,6,7,8,9)), range(10))
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# Test an xrange
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def test_iter_xrange(self):
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self.check_for_loop(iter(xrange(10)), range(10))
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# Test a string
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def test_iter_string(self):
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self.check_for_loop(iter("abcde"), ["a", "b", "c", "d", "e"])
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# Test a Unicode string
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def test_iter_unicode(self):
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self.check_for_loop(iter(u"abcde"), [u"a", u"b", u"c", u"d", u"e"])
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# Test a directory
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def test_iter_dict(self):
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dict = {}
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for i in range(10):
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dict[i] = None
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self.check_for_loop(dict, dict.keys())
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# Test a file
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def test_iter_file(self):
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f = open(TESTFN, "w")
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try:
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for i in range(5):
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f.write("%d\n" % i)
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finally:
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f.close()
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f = open(TESTFN, "r")
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try:
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self.check_for_loop(f, ["0\n", "1\n", "2\n", "3\n", "4\n"])
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self.check_for_loop(f, [])
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finally:
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f.close()
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try:
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unlink(TESTFN)
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except OSError:
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pass
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run_unittest(TestCase)
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