Lib/test/test_setcomps.py

   1 doctests = """
   2 ########### Tests mostly copied from test_listcomps.py ############
   3
   4 Test simple loop with conditional
   5
   6     >>> sum({i*i for i in range(100) if i&1 == 1})
   7     166650
   8
   9 Test simple case
  10
  11     >>> {2*y + x + 1 for x in (0,) for y in (1,)}
  12     set([3])
  13
  14 Test simple nesting
  15
  16     >>> list(sorted({(i,j) for i in range(3) for j in range(4)}))
  17     [(0, 0), (0, 1), (0, 2), (0, 3), (1, 0), (1, 1), (1, 2), (1, 3), (2, 0), (2, 1), (2, 2), (2, 3)]
  18
  19 Test nesting with the inner expression dependent on the outer
  20
  21     >>> list(sorted({(i,j) for i in range(4) for j in range(i)}))
  22     [(1, 0), (2, 0), (2, 1), (3, 0), (3, 1), (3, 2)]
  23
  24 Make sure the induction variable is not exposed
  25
  26     >>> i = 20
  27     >>> sum({i*i for i in range(100)})
  28     328350
  29
  30     >>> i
  31     20
  32
  33 Verify that syntax error's are raised for setcomps used as lvalues
  34
  35     >>> {y for y in (1,2)} = 10          # doctest: +IGNORE_EXCEPTION_DETAIL
  36     Traceback (most recent call last):
  37        ...
  38     SyntaxError: ...
  39
  40     >>> {y for y in (1,2)} += 10         # doctest: +IGNORE_EXCEPTION_DETAIL
  41     Traceback (most recent call last):
  42        ...
  43     SyntaxError: ...
  44
  45
  46 Make a nested set comprehension that acts like set(range())
  47
  48     >>> def srange(n):
  49     ...     return {i for i in range(n)}
  50     >>> list(sorted(srange(10)))
  51     [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
  52
  53 Same again, only as a lambda expression instead of a function definition
  54
  55     >>> lrange = lambda n:  {i for i in range(n)}
  56     >>> list(sorted(lrange(10)))
  57     [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
  58
  59 Generators can call other generators:
  60
  61     >>> def grange(n):
  62     ...     for x in {i for i in range(n)}:
  63     ...         yield x
  64     >>> list(sorted(grange(5)))
  65     [0, 1, 2, 3, 4]
  66
  67
  68 Make sure that None is a valid return value
  69
  70     >>> {None for i in range(10)}
  71     set([None])
  72
  73 ########### Tests for various scoping corner cases ############
  74
  75 Return lambdas that use the iteration variable as a default argument
  76
  77     >>> items = {(lambda i=i: i) for i in range(5)}
  78     >>> {x() for x in items} == set(range(5))
  79     True
  80
  81 Same again, only this time as a closure variable
  82
  83     >>> items = {(lambda: i) for i in range(5)}
  84     >>> {x() for x in items}
  85     set([4])
  86
  87 Another way to test that the iteration variable is local to the list comp
  88
  89     >>> items = {(lambda: i) for i in range(5)}
  90     >>> i = 20
  91     >>> {x() for x in items}
  92     set([4])
  93
  94 And confirm that a closure can jump over the list comp scope
  95
  96     >>> items = {(lambda: y) for i in range(5)}
  97     >>> y = 2
  98     >>> {x() for x in items}
  99     set([2])
 100
 101 We also repeat each of the above scoping tests inside a function
 102
 103     >>> def test_func():
 104     ...     items = {(lambda i=i: i) for i in range(5)}
 105     ...     return {x() for x in items}
 106     >>> test_func() == set(range(5))
 107     True
 108
 109     >>> def test_func():
 110     ...     items = {(lambda: i) for i in range(5)}
 111     ...     return {x() for x in items}
 112     >>> test_func()
 113     set([4])
 114
 115     >>> def test_func():
 116     ...     items = {(lambda: i) for i in range(5)}
 117     ...     i = 20
 118     ...     return {x() for x in items}
 119     >>> test_func()
 120     set([4])
 121
 122     >>> def test_func():
 123     ...     items = {(lambda: y) for i in range(5)}
 124     ...     y = 2
 125     ...     return {x() for x in items}
 126     >>> test_func()
 127     set([2])
 128
 129 """
 130
 131
 132 __test__ = {'doctests' : doctests}
 133
 134 def test_main(verbose=None):
 135     import sys
 136     from test import test_support
 137     from test import test_setcomps
 138     test_support.run_doctest(test_setcomps, verbose)
 139
 140     # verify reference counting
 141     if verbose and hasattr(sys, "gettotalrefcount"):
 142         import gc
 143         counts = [None] * 5
 144         for i in range(len(counts)):
 145             test_support.run_doctest(test_setcomps, verbose)
 146             gc.collect()
 147             counts[i] = sys.gettotalrefcount()
 148         print(counts)
 149
 150 if __name__ == "__main__":
 151     test_main(verbose=True)