1 from test import test_support, seq_tests

     2 

     3 class TupleTest(seq_tests.CommonTest):

     4     type2test = tuple

     5 

     6     def test_constructors(self):

     7         super(TupleTest, self).test_len()

     8         # calling built-in types without argument must return empty

     9         self.assertEqual(tuple(), ())

    10         t0_3 = (0, 1, 2, 3)

    11         t0_3_bis = tuple(t0_3)

    12         self.assert_(t0_3 is t0_3_bis)

    13         self.assertEqual(tuple([]), ())

    14         self.assertEqual(tuple([0, 1, 2, 3]), (0, 1, 2, 3))

    15         self.assertEqual(tuple(''), ())

    16         self.assertEqual(tuple('spam'), ('s', 'p', 'a', 'm'))

    17 

    18     def test_truth(self):

    19         super(TupleTest, self).test_truth()

    20         self.assert_(not ())

    21         self.assert_((42, ))

    22 

    23     def test_len(self):

    24         super(TupleTest, self).test_len()

    25         self.assertEqual(len(()), 0)

    26         self.assertEqual(len((0,)), 1)

    27         self.assertEqual(len((0, 1, 2)), 3)

    28 

    29     def test_iadd(self):

    30         super(TupleTest, self).test_iadd()

    31         u = (0, 1)

    32         u2 = u

    33         u += (2, 3)

    34         self.assert_(u is not u2)

    35 

    36     def test_imul(self):

    37         super(TupleTest, self).test_imul()

    38         u = (0, 1)

    39         u2 = u

    40         u *= 3

    41         self.assert_(u is not u2)

    42 

    43     def test_tupleresizebug(self):

    44         # Check that a specific bug in _PyTuple_Resize() is squashed.

    45         def f():

    46             for i in range(1000):

    47                 yield i

    48         self.assertEqual(list(tuple(f())), range(1000))

    49 

    50     def test_hash(self):

    51         # See SF bug 942952:  Weakness in tuple hash

    52         # The hash should:

    53         #      be non-commutative

    54         #      should spread-out closely spaced values

    55         #      should not exhibit cancellation in tuples like (x,(x,y))

    56         #      should be distinct from element hashes:  hash(x)!=hash((x,))

    57         # This test exercises those cases.

    58         # For a pure random hash and N=50, the expected number of occupied

    59         #      buckets when tossing 252,600 balls into 2**32 buckets

    60         #      is 252,592.6, or about 7.4 expected collisions.  The

    61         #      standard deviation is 2.73.  On a box with 64-bit hash

    62         #      codes, no collisions are expected.  Here we accept no

    63         #      more than 15 collisions.  Any worse and the hash function

    64         #      is sorely suspect.

    65 

    66         N=50

    67         base = range(N)

    68         xp = [(i, j) for i in base for j in base]

    69         inps = base + [(i, j) for i in base for j in xp] + \

    70                      [(i, j) for i in xp for j in base] + xp + zip(base)

    71         collisions = len(inps) - len(set(map(hash, inps)))

    72         self.assert_(collisions <= 15)

    73 

    74     def test_repr(self):

    75         l0 = tuple()

    76         l2 = (0, 1, 2)

    77         a0 = self.type2test(l0)

    78         a2 = self.type2test(l2)

    79 

    80         self.assertEqual(str(a0), repr(l0))

    81         self.assertEqual(str(a2), repr(l2))

    82         self.assertEqual(repr(a0), "()")

    83         self.assertEqual(repr(a2), "(0, 1, 2)")

    84 

    85 def test_main():

    86     test_support.run_unittest(TupleTest)

    87 

    88 if __name__=="__main__":

    89     test_main()