Lib/test/test_xrange.py

   1 # Python test set -- built-in functions
   2
   3 import test.test_support, unittest
   4 import sys
   5 import pickle
   6 import itertools
   7
   8 import warnings
   9 warnings.filterwarnings("ignore", "integer argument expected",
  10                         DeprecationWarning, "unittest")
  11
  12 # pure Python implementations (3 args only), for comparison
  13 def pyrange(start, stop, step):
  14     if (start - stop) // step < 0:
  15         # replace stop with next element in the sequence of integers
  16         # that are congruent to start modulo step.
  17         stop += (start - stop) % step
  18         while start != stop:
  19             yield start
  20             start += step
  21
  22 def pyrange_reversed(start, stop, step):
  23     stop += (start - stop) % step
  24     return pyrange(stop - step, start - step, -step)
  25
  26
  27 class XrangeTest(unittest.TestCase):
  28     def assert_iterators_equal(self, xs, ys, test_id, limit=None):
  29         # check that an iterator xs matches the expected results ys,
  30         # up to a given limit.
  31         if limit is not None:
  32             xs = itertools.islice(xs, limit)
  33             ys = itertools.islice(ys, limit)
  34         sentinel = object()
  35         pairs = itertools.izip_longest(xs, ys, fillvalue=sentinel)
  36         for i, (x, y) in enumerate(pairs):
  37             if x == y:
  38                 continue
  39             elif x == sentinel:
  40                 self.fail('{}: iterator ended unexpectedly '
  41                           'at position {}; expected {}'.format(test_id, i, y))
  42             elif y == sentinel:
  43                 self.fail('{}: unexpected excess element {} at '
  44                           'position {}'.format(test_id, x, i))
  45             else:
  46                 self.fail('{}: wrong element at position {};'
  47                           'expected {}, got {}'.format(test_id, i, y, x))
  48
  49     def test_xrange(self):
  50         self.assertEqual(list(xrange(3)), [0, 1, 2])
  51         self.assertEqual(list(xrange(1, 5)), [1, 2, 3, 4])
  52         self.assertEqual(list(xrange(0)), [])
  53         self.assertEqual(list(xrange(-3)), [])
  54         self.assertEqual(list(xrange(1, 10, 3)), [1, 4, 7])
  55         self.assertEqual(list(xrange(5, -5, -3)), [5, 2, -1, -4])
  56
  57         a = 10
  58         b = 100
  59         c = 50
  60
  61         self.assertEqual(list(xrange(a, a+2)), [a, a+1])
  62         self.assertEqual(list(xrange(a+2, a, -1L)), [a+2, a+1])
  63         self.assertEqual(list(xrange(a+4, a, -2)), [a+4, a+2])
  64
  65         seq = list(xrange(a, b, c))
  66         self.assertIn(a, seq)
  67         self.assertNotIn(b, seq)
  68         self.assertEqual(len(seq), 2)
  69
  70         seq = list(xrange(b, a, -c))
  71         self.assertIn(b, seq)
  72         self.assertNotIn(a, seq)
  73         self.assertEqual(len(seq), 2)
  74
  75         seq = list(xrange(-a, -b, -c))
  76         self.assertIn(-a, seq)
  77         self.assertNotIn(-b, seq)
  78         self.assertEqual(len(seq), 2)
  79
  80         self.assertRaises(TypeError, xrange)
  81         self.assertRaises(TypeError, xrange, 1, 2, 3, 4)
  82         self.assertRaises(ValueError, xrange, 1, 2, 0)
  83
  84         self.assertRaises(OverflowError, xrange, 10**100, 10**101, 10**101)
  85
  86         self.assertRaises(TypeError, xrange, 0, "spam")
  87         self.assertRaises(TypeError, xrange, 0, 42, "spam")
  88
  89         self.assertEqual(len(xrange(0, sys.maxint, sys.maxint-1)), 2)
  90
  91         self.assertRaises(OverflowError, xrange, -sys.maxint, sys.maxint)
  92         self.assertRaises(OverflowError, xrange, 0, 2*sys.maxint)
  93
  94         r = xrange(-sys.maxint, sys.maxint, 2)
  95         self.assertEqual(len(r), sys.maxint)
  96         self.assertRaises(OverflowError, xrange, -sys.maxint-1, sys.maxint, 2)
  97
  98     def test_pickling(self):
  99         testcases = [(13,), (0, 11), (-22, 10), (20, 3, -1),
 100                      (13, 21, 3), (-2, 2, 2)]
 101         for proto in range(pickle.HIGHEST_PROTOCOL + 1):
 102             for t in testcases:
 103                 r = xrange(*t)
 104                 self.assertEquals(list(pickle.loads(pickle.dumps(r, proto))),
 105                                   list(r))
 106
 107     def test_range_iterators(self):
 108         # see issue 7298
 109         limits = [base + jiggle
 110                   for M in (2**32, 2**64)
 111                   for base in (-M, -M//2, 0, M//2, M)
 112                   for jiggle in (-2, -1, 0, 1, 2)]
 113         test_ranges = [(start, end, step)
 114                        for start in limits
 115                        for end in limits
 116                        for step in (-2**63, -2**31, -2, -1, 1, 2)]
 117
 118         for start, end, step in test_ranges:
 119             try:
 120                 iter1 = xrange(start, end, step)
 121             except OverflowError:
 122                 pass
 123             else:
 124                 iter2 = pyrange(start, end, step)
 125                 test_id = "xrange({}, {}, {})".format(start, end, step)
 126                 # check first 100 entries
 127                 self.assert_iterators_equal(iter1, iter2, test_id, limit=100)
 128
 129             try:
 130                 iter1 = reversed(xrange(start, end, step))
 131             except OverflowError:
 132                 pass
 133             else:
 134                 iter2 = pyrange_reversed(start, end, step)
 135                 test_id = "reversed(xrange({}, {}, {}))".format(start, end, step)
 136                 self.assert_iterators_equal(iter1, iter2, test_id, limit=100)
 137
 138
 139 def test_main():
 140     test.test_support.run_unittest(XrangeTest)
 141
 142 if __name__ == "__main__":
 143     test_main()