Lib/test/test_range.py

# Python test set -- built-in functions

import test.support, unittest
import sys
import pickle
import itertools

import warnings
warnings.filterwarnings("ignore", "integer argument expected",
                        DeprecationWarning, "unittest")

# pure Python implementations (3 args only), for comparison
def pyrange(start, stop, step):
    if (start - stop) // step < 0:
        # replace stop with next element in the sequence of integers
        # that are congruent to start modulo step.
        stop += (start - stop) % step
        while start != stop:
            yield start
            start += step

def pyrange_reversed(start, stop, step):
    stop += (start - stop) % step
    return pyrange(stop - step, start - step, -step)


class RangeTest(unittest.TestCase):
    def assert_iterators_equal(self, xs, ys, test_id, limit=None):
        # check that an iterator xs matches the expected results ys,
        # up to a given limit.
        if limit is not None:
            xs = itertools.islice(xs, limit)
            ys = itertools.islice(ys, limit)
        sentinel = object()
        pairs = itertools.zip_longest(xs, ys, fillvalue=sentinel)
        for i, (x, y) in enumerate(pairs):
            if x == y:
                continue
            elif x == sentinel:
                self.fail('{}: iterator ended unexpectedly '
                          'at position {}; expected {}'.format(test_id, i, y))
            elif y == sentinel:
                self.fail('{}: unexpected excess element {} at '
                          'position {}'.format(test_id, x, i))
            else:
                self.fail('{}: wrong element at position {};'
                          'expected {}, got {}'.format(test_id, i, y, x))

    def test_range(self):
        self.assertEqual(list(range(3)), [0, 1, 2])
        self.assertEqual(list(range(1, 5)), [1, 2, 3, 4])
        self.assertEqual(list(range(0)), [])
        self.assertEqual(list(range(-3)), [])
        self.assertEqual(list(range(1, 10, 3)), [1, 4, 7])
        self.assertEqual(list(range(5, -5, -3)), [5, 2, -1, -4])

        a = 10
        b = 100
        c = 50

        self.assertEqual(list(range(a, a+2)), [a, a+1])
        self.assertEqual(list(range(a+2, a, -1)), [a+2, a+1])
        self.assertEqual(list(range(a+4, a, -2)), [a+4, a+2])

        seq = list(range(a, b, c))
        self.assertTrue(a in seq)
        self.assertTrue(b not in seq)
        self.assertEqual(len(seq), 2)

        seq = list(range(b, a, -c))
        self.assertTrue(b in seq)
        self.assertTrue(a not in seq)
        self.assertEqual(len(seq), 2)

        seq = list(range(-a, -b, -c))
        self.assertTrue(-a in seq)
        self.assertTrue(-b not in seq)
        self.assertEqual(len(seq), 2)

        self.assertRaises(TypeError, range)
        self.assertRaises(TypeError, range, 1, 2, 3, 4)
        self.assertRaises(ValueError, range, 1, 2, 0)

        self.assertRaises(TypeError, range, 0.0, 2, 1)
        self.assertRaises(TypeError, range, 1, 2.0, 1)
        self.assertRaises(TypeError, range, 1, 2, 1.0)
        self.assertRaises(TypeError, range, 1e100, 1e101, 1e101)

        self.assertRaises(TypeError, range, 0, "spam")
        self.assertRaises(TypeError, range, 0, 42, "spam")

        self.assertEqual(len(range(0, sys.maxsize, sys.maxsize-1)), 2)

        r = range(-sys.maxsize, sys.maxsize, 2)
        self.assertEqual(len(r), sys.maxsize)

    def test_repr(self):
        self.assertEqual(repr(range(1)), 'range(0, 1)')
        self.assertEqual(repr(range(1, 2)), 'range(1, 2)')
        self.assertEqual(repr(range(1, 2, 3)), 'range(1, 2, 3)')

    def test_pickling(self):
        testcases = [(13,), (0, 11), (-22, 10), (20, 3, -1),
                     (13, 21, 3), (-2, 2, 2)]
        for proto in range(pickle.HIGHEST_PROTOCOL + 1):
            for t in testcases:
                r = range(*t)
                self.assertEquals(list(pickle.loads(pickle.dumps(r, proto))),
                                  list(r))

    def test_odd_bug(self):
        # This used to raise a "SystemError: NULL result without error"
        # because the range validation step was eating the exception
        # before NULL was returned.
        with self.assertRaises(TypeError):
            range([], 1, -1)

    def test_types(self):
        # Non-integer objects *equal* to any of the range's items are supposed
        # to be contained in the range.
        self.assertTrue(1.0 in range(3))
        self.assertTrue(True in range(3))
        self.assertTrue(1+0j in range(3))

        class C1:
            def __eq__(self, other): return True
        self.assertTrue(C1() in range(3))

        # Objects are never coerced into other types for comparison.
        class C2:
            def __int__(self): return 1
            def __index__(self): return 1
        self.assertFalse(C2() in range(3))
        # ..except if explicitly told so.
        self.assertTrue(int(C2()) in range(3))

        # Check that the range.__contains__ optimization is only
        # used for ints, not for instances of subclasses of int.
        class C3(int):
            def __eq__(self, other): return True
        self.assertTrue(C3(11) in range(10))
        self.assertTrue(C3(11) in list(range(10)))

    def test_strided_limits(self):
        r = range(0, 101, 2)
        self.assertTrue(0 in r)
        self.assertFalse(1 in r)
        self.assertTrue(2 in r)
        self.assertFalse(99 in r)
        self.assertTrue(100 in r)
        self.assertFalse(101 in r)

        r = range(0, -20, -1)
        self.assertTrue(0 in r)
        self.assertTrue(-1 in r)
        self.assertTrue(-19 in r)
        self.assertFalse(-20 in r)

        r = range(0, -20, -2)
        self.assertTrue(-18 in r)
        self.assertFalse(-19 in r)
        self.assertFalse(-20 in r)

    def test_empty(self):
        r = range(0)
        self.assertFalse(0 in r)
        self.assertFalse(1 in r)

        r = range(0, -10)
        self.assertFalse(0 in r)
        self.assertFalse(-1 in r)
        self.assertFalse(1 in r)

    def test_range_iterators(self):
        # exercise 'fast' iterators, that use a rangeiterobject internally.
        # see issue 7298
        limits = [base + jiggle
                  for M in (2**32, 2**64)
                  for base in (-M, -M//2, 0, M//2, M)
                  for jiggle in (-2, -1, 0, 1, 2)]
        test_ranges = [(start, end, step)
                       for start in limits
                       for end in limits
                       for step in (-2**63, -2**31, -2, -1, 1, 2)]

        for start, end, step in test_ranges:
            iter1 = range(start, end, step)
            iter2 = pyrange(start, end, step)
            test_id = "range({}, {}, {})".format(start, end, step)
            # check first 100 entries
            self.assert_iterators_equal(iter1, iter2, test_id, limit=100)

            iter1 = reversed(range(start, end, step))
            iter2 = pyrange_reversed(start, end, step)
            test_id = "reversed(range({}, {}, {}))".format(start, end, step)
            self.assert_iterators_equal(iter1, iter2, test_id, limit=100)

def test_main():
    test.support.run_unittest(RangeTest)

if __name__ == "__main__":
    test_main()