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