# Test iterators. import sys import unittest from test.support import cpython_only from test.support.os_helper import TESTFN, unlink from test.support import check_free_after_iterating, ALWAYS_EQ, NEVER_EQ import pickle import collections.abc import functools import contextlib import builtins # 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 def __iter__(self): return self class IteratingSequenceClass: def __init__(self, n): self.n = n def __iter__(self): return BasicIterClass(self.n) class IteratorProxyClass: def __init__(self, i): self.i = i def __next__(self): return next(self.i) def __iter__(self): return self class SequenceClass: def __init__(self, n): self.n = n def __getitem__(self, i): if 0 <= i < self.n: return i else: raise IndexError class SequenceProxyClass: def __init__(self, s): self.s = s def __getitem__(self, i): return self.s[i] class UnlimitedSequenceClass: def __getitem__(self, i): return i class DefaultIterClass: pass class NoIterClass: def __getitem__(self, i): return i __iter__ = None class BadIterableClass: def __iter__(self): raise ZeroDivisionError class CallableIterClass: 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 class EmptyIterClass: def __len__(self): return 0 def __getitem__(self, i): raise StopIteration # Main test suite class TestCase(unittest.TestCase): # Helper to check that an iterator returns a given sequence def check_iterator(self, it, seq, pickle=True): if pickle: self.check_pickle(it, seq) res = [] while 1: try: val = next(it) 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, pickle=True): if pickle: self.check_pickle(iter(expr), seq) res = [] for val in expr: res.append(val) self.assertEqual(res, seq) # 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) # Cannot assert type equality because dict iterators unpickle as list # iterators. # self.assertEqual(type(itorg), type(it)) self.assertTrue(isinstance(it, collections.abc.Iterator)) self.assertEqual(list(it), seq) it = pickle.loads(d) try: next(it) except StopIteration: continue d = pickle.dumps(it, proto) it = pickle.loads(d) self.assertEqual(list(it), seq[1:]) # Test basic use of iter() function def test_iter_basic(self): self.check_iterator(iter(range(10)), list(range(10))) # Test that iter(iter(x)) is the same as iter(x) def test_iter_idempotency(self): seq = list(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)), list(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), list(range(10))) # Test a class with __iter__ with explicit iter() def test_iter_class_iter(self): self.check_iterator(iter(IteratingSequenceClass(10)), list(range(10))) # Test for loop on a sequence class without __iter__ def test_seq_class_for(self): self.check_for_loop(SequenceClass(10), list(range(10))) # Test iter() on a sequence class without __iter__ def test_seq_class_iter(self): self.check_iterator(iter(SequenceClass(10)), list(range(10))) def test_mutating_seq_class_iter_pickle(self): orig = SequenceClass(5) for proto in range(pickle.HIGHEST_PROTOCOL + 1): # initial iterator itorig = iter(orig) d = pickle.dumps((itorig, orig), proto) it, seq = pickle.loads(d) seq.n = 7 self.assertIs(type(it), type(itorig)) self.assertEqual(list(it), list(range(7))) # running iterator next(itorig) d = pickle.dumps((itorig, orig), proto) it, seq = pickle.loads(d) seq.n = 7 self.assertIs(type(it), type(itorig)) self.assertEqual(list(it), list(range(1, 7))) # empty iterator for i in range(1, 5): next(itorig) d = pickle.dumps((itorig, orig), proto) it, seq = pickle.loads(d) seq.n = 7 self.assertIs(type(it), type(itorig)) self.assertEqual(list(it), list(range(5, 7))) # exhausted iterator self.assertRaises(StopIteration, next, itorig) d = pickle.dumps((itorig, orig), proto) it, seq = pickle.loads(d) seq.n = 7 self.assertTrue(isinstance(it, collections.abc.Iterator)) self.assertEqual(list(it), []) def test_mutating_seq_class_exhausted_iter(self): a = SequenceClass(5) exhit = iter(a) empit = iter(a) for x in exhit: # exhaust the iterator next(empit) # not exhausted a.n = 7 self.assertEqual(list(exhit), []) self.assertEqual(list(empit), [5, 6]) self.assertEqual(list(a), [0, 1, 2, 3, 4, 5, 6]) def test_reduce_mutating_builtins_iter(self): # This is a reproducer of issue #101765 # where iter `__reduce__` calls could lead to a segfault or SystemError # depending on the order of C argument evaluation, which is undefined # Backup builtins builtins_dict = builtins.__dict__ orig = {"iter": iter, "reversed": reversed} def run(builtin_name, item, sentinel=None): it = iter(item) if sentinel is None else iter(item, sentinel) class CustomStr: def __init__(self, name, iterator): self.name = name self.iterator = iterator def __hash__(self): return hash(self.name) def __eq__(self, other): # Here we exhaust our iterator, possibly changing # its `it_seq` pointer to NULL # The `__reduce__` call should correctly get # the pointers after this call list(self.iterator) return other == self.name # del is required here # to not prematurely call __eq__ from # the hash collision with the old key del builtins_dict[builtin_name] builtins_dict[CustomStr(builtin_name, it)] = orig[builtin_name] return it.__reduce__() types = [ (EmptyIterClass(),), (bytes(8),), (bytearray(8),), ((1, 2, 3),), (lambda: 0, 0), (tuple[int],) # GenericAlias ] try: run_iter = functools.partial(run, "iter") # The returned value of `__reduce__` should not only be valid # but also *empty*, as `it` was exhausted during `__eq__` # i.e "xyz" returns (iter, ("",)) self.assertEqual(run_iter("xyz"), (orig["iter"], ("",))) self.assertEqual(run_iter([1, 2, 3]), (orig["iter"], ([],))) # _PyEval_GetBuiltin is also called for `reversed` in a branch of # listiter_reduce_general self.assertEqual( run("reversed", orig["reversed"](list(range(8)))), (iter, ([],)) ) for case in types: self.assertEqual(run_iter(*case), (orig["iter"], ((),))) finally: # Restore original builtins for key, func in orig.items(): # need to suppress KeyErrors in case # a failed test deletes the key without setting anything with contextlib.suppress(KeyError): # del is required here # to not invoke our custom __eq__ from # the hash collision with the old key del builtins_dict[key] builtins_dict[key] = func # 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): self.check_iterator(iter(CallableIterClass(), 10), list(range(10)), pickle=True) # 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), list(range(10)), pickle=False) # 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), list(range(10)), pickle=False) def test_iter_function_concealing_reentrant_exhaustion(self): # gh-101892: Test two-argument iter() with a function that # exhausts its associated iterator but forgets to either return # a sentinel value or raise StopIteration. HAS_MORE = 1 NO_MORE = 2 def exhaust(iterator): """Exhaust an iterator without raising StopIteration.""" list(iterator) def spam(): # Touching the iterator with exhaust() below will call # spam() once again so protect against recursion. if spam.is_recursive_call: return NO_MORE spam.is_recursive_call = True exhaust(spam.iterator) return HAS_MORE spam.is_recursive_call = False spam.iterator = iter(spam, NO_MORE) with self.assertRaises(StopIteration): next(spam.iterator) # 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, list(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, list(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), list(range(10)), pickle=False) # Test a big range def test_iter_big_range(self): self.check_for_loop(iter(range(10000)), list(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)), list(range(10))) # Test a range def test_iter_range(self): self.check_for_loop(iter(range(10)), list(range(10))) # Test a string def test_iter_string(self): self.check_for_loop(iter("abcde"), ["a", "b", "c", "d", "e"]) # Test a directory def test_iter_dict(self): dict = {} for i in range(10): dict[i] = None self.check_for_loop(dict, list(dict.keys())) # Test a file def test_iter_file(self): f = open(TESTFN, "w", encoding="utf-8") try: for i in range(5): f.write("%d\n" % i) finally: f.close() f = open(TESTFN, "r", encoding="utf-8") try: self.check_for_loop(f, ["0\n", "1\n", "2\n", "3\n", "4\n"], pickle=False) self.check_for_loop(f, [], pickle=False) 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)), list(range(5))) self.assertEqual(list(SequenceClass(0)), []) self.assertEqual(list(()), []) d = {"one": 1, "two": 2, "three": 3} self.assertEqual(list(d), list(d.keys())) self.assertRaises(TypeError, list, list) self.assertRaises(TypeError, list, 42) f = open(TESTFN, "w", encoding="utf-8") try: for i in range(5): f.write("%d\n" % i) finally: f.close() f = open(TESTFN, "r", encoding="utf-8") 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", encoding="utf-8") try: for i in range(5): f.write("%d\n" % i) finally: f.close() f = open(TESTFN, "r", encoding="utf-8") 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(list(filter(None, SequenceClass(5))), list(range(1, 5))) self.assertEqual(list(filter(None, SequenceClass(0))), []) self.assertEqual(list(filter(None, ())), []) self.assertEqual(list(filter(None, "abc")), ["a", "b", "c"]) d = {"one": 1, "two": 2, "three": 3} self.assertEqual(list(filter(None, d)), list(d.keys())) self.assertRaises(TypeError, filter, None, list) self.assertRaises(TypeError, filter, None, 42) class Boolean: def __init__(self, truth): self.truth = truth def __bool__(self): return self.truth bTrue = Boolean(True) bFalse = Boolean(False) 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(list(filter(lambda x: not x, seq)), [bFalse]*25) self.assertEqual(list(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.values()), 3) self.assertEqual(min(iter(d.values())), 1) f = open(TESTFN, "w", encoding="utf-8") 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", encoding="utf-8") 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(list(map(lambda x: x+1, SequenceClass(5))), list(range(1, 6))) d = {"one": 1, "two": 2, "three": 3} self.assertEqual(list(map(lambda k, d=d: (k, d[k]), d)), list(d.items())) dkeys = list(d.keys()) expected = [(i < len(d) and dkeys[i] or None, i, i < len(d) and dkeys[i] or None) for i in range(3)] f = open(TESTFN, "w", encoding="utf-8") 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", encoding="utf-8") try: self.assertEqual(list(map(len, f)), list(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(list(zip()), []) self.assertEqual(list(zip(*[])), []) self.assertEqual(list(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(list(zip(IteratingSequenceClass(3))), [(0,), (1,), (2,)]) self.assertEqual(list(zip(SequenceClass(3))), [(0,), (1,), (2,)]) d = {"one": 1, "two": 2, "three": 3} self.assertEqual(list(d.items()), list(zip(d, d.values()))) # 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", encoding="utf-8") try: f.write("a\n" "bbb\n" "cc\n") finally: f.close() f = open(TESTFN, "r", encoding="utf-8") try: self.assertEqual(list(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(list(zip(range(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 def lzip(*args): return list(zip(*args)) self.assertEqual(len(Guess3Len5()), 3) self.assertEqual(len(Guess30Len5()), 30) self.assertEqual(lzip(NoGuessLen5()), lzip(range(5))) self.assertEqual(lzip(Guess3Len5()), lzip(range(5))) self.assertEqual(lzip(Guess30Len5()), lzip(range(5))) expected = [(i, i) for i in range(5)] for x in NoGuessLen5(), Guess3Len5(), Guess30Len5(): for y in NoGuessLen5(), Guess3Len5(), Guess30Len5(): self.assertEqual(lzip(x, y), expected) 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 "fooled you!" return next(self.it) f = open(TESTFN, "w", encoding="utf-8") try: f.write("a\n" + "b\n" + "c\n") finally: f.close() f = open(TESTFN, "r", encoding="utf-8") # 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, "a\n - b\n - fooled you! - c\n") finally: f.close() try: unlink(TESTFN) except OSError: 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.assertIn(ALWAYS_EQ, IteratorProxyClass(iter([1]))) self.assertIn(ALWAYS_EQ, SequenceProxyClass([1])) self.assertNotIn(ALWAYS_EQ, IteratorProxyClass(iter([NEVER_EQ]))) self.assertNotIn(ALWAYS_EQ, SequenceProxyClass([NEVER_EQ])) self.assertIn(NEVER_EQ, IteratorProxyClass(iter([ALWAYS_EQ]))) self.assertIn(NEVER_EQ, SequenceProxyClass([ALWAYS_EQ])) self.assertRaises(TypeError, lambda: 3 in 12) self.assertRaises(TypeError, lambda: 3 not in map) self.assertRaises(ZeroDivisionError, lambda: 3 in BadIterableClass()) d = {"one": 1, "two": 2, "three": 3, 1j: 2j} for k in d: self.assertIn(k, d) self.assertNotIn(k, d.values()) for v in d.values(): self.assertIn(v, d.values()) self.assertNotIn(v, d) for k, v in d.items(): self.assertIn((k, v), d.items()) self.assertNotIn((v, k), d.items()) f = open(TESTFN, "w", encoding="utf-8") try: f.write("a\n" "b\n" "c\n") finally: f.close() f = open(TESTFN, "r", encoding="utf-8") 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.values(), 3), 3) self.assertEqual(countOf(d.values(), 2j), 1) self.assertEqual(countOf(d.values(), 1j), 0) f = open(TESTFN, "w", encoding="utf-8") try: f.write("a\n" "b\n" "c\n" "b\n") finally: f.close() f = open(TESTFN, "r", encoding="utf-8") 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) self.assertRaises(ZeroDivisionError, indexOf, BadIterableClass(), 1) f = open(TESTFN, "w", encoding="utf-8") try: f.write("a\n" "b\n" "c\n" "d\n" "e\n") finally: f.close() f = open(TESTFN, "r", encoding="utf-8") 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 = open(TESTFN, "w", encoding="utf-8") 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 = open(TESTFN, encoding="utf-8") 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}.values() self.assertEqual((a, b, c), (42, 42, 42)) f = open(TESTFN, "w", encoding="utf-8") lines = ("a\n", "bb\n", "ccc\n") try: for line in lines: f.write(line) finally: f.close() f = open(TESTFN, "r", encoding="utf-8") 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 = list(range(5)) b = iter(a) self.assertEqual(list(b), list(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), list(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), list(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), list(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.keys(), a.items(), a.values(): 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), list(range(5))) self.assertEqual(list(b), []) def test_sinkstate_range(self): a = range(5) b = iter(a) self.assertEqual(list(b), list(range(5))) self.assertEqual(list(b), []) def test_sinkstate_enumerate(self): a = range(5) e = enumerate(a) b = iter(e) self.assertEqual(list(b), list(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) @cpython_only def test_iter_overflow(self): # Test for the issue 22939 it = iter(UnlimitedSequenceClass()) # Manually set `it_index` to PY_SSIZE_T_MAX-2 without a loop it.__setstate__(sys.maxsize - 2) self.assertEqual(next(it), sys.maxsize - 2) self.assertEqual(next(it), sys.maxsize - 1) with self.assertRaises(OverflowError): next(it) # Check that Overflow error is always raised with self.assertRaises(OverflowError): next(it) def test_iter_neg_setstate(self): it = iter(UnlimitedSequenceClass()) it.__setstate__(-42) self.assertEqual(next(it), 0) self.assertEqual(next(it), 1) def test_free_after_iterating(self): check_free_after_iterating(self, iter, SequenceClass, (0,)) def test_error_iter(self): for typ in (DefaultIterClass, NoIterClass): self.assertRaises(TypeError, iter, typ()) self.assertRaises(ZeroDivisionError, iter, BadIterableClass()) if __name__ == "__main__": unittest.main()