Lib/test/test_unpack.py

   1 from test.test_support import TestFailed, verbose
   2
   3 t = (1, 2, 3)
   4 l = [4, 5, 6]
   5
   6 class Seq:
   7     def __getitem__(self, i):
   8         if i >= 0 and i < 3: return i
   9         raise IndexError
  10
  11 a = -1
  12 b = -1
  13 c = -1
  14
  15 # unpack tuple
  16 if verbose:
  17     print 'unpack tuple'
  18 a, b, c = t
  19 if a != 1 or b != 2 or c != 3:
  20     raise TestFailed
  21
  22 # unpack list
  23 if verbose:
  24     print 'unpack list'
  25 a, b, c = l
  26 if a != 4 or b != 5 or c != 6:
  27     raise TestFailed
  28
  29 # unpack implied tuple
  30 if verbose:
  31     print 'unpack implied tuple'
  32 a, b, c = 7, 8, 9
  33 if a != 7 or b != 8 or c != 9:
  34     raise TestFailed
  35
  36 # unpack string... fun!
  37 if verbose:
  38     print 'unpack string'
  39 a, b, c = 'one'
  40 if a != 'o' or b != 'n' or c != 'e':
  41     raise TestFailed
  42
  43 # unpack generic sequence
  44 if verbose:
  45     print 'unpack sequence'
  46 a, b, c = Seq()
  47 if a != 0 or b != 1 or c != 2:
  48     raise TestFailed
  49
  50 # single element unpacking, with extra syntax
  51 if verbose:
  52     print 'unpack single tuple/list'
  53 st = (99,)
  54 sl = [100]
  55 a, = st
  56 if a != 99:
  57     raise TestFailed
  58 b, = sl
  59 if b != 100:
  60     raise TestFailed
  61
  62 # now for some failures
  63
  64 # unpacking non-sequence
  65 if verbose:
  66     print 'unpack non-sequence'
  67 try:
  68     a, b, c = 7
  69     raise TestFailed
  70 except TypeError:
  71     pass
  72
  73
  74 # unpacking tuple of wrong size
  75 if verbose:
  76     print 'unpack tuple wrong size'
  77 try:
  78     a, b = t
  79     raise TestFailed
  80 except ValueError:
  81     pass
  82
  83 # unpacking list of wrong size
  84 if verbose:
  85     print 'unpack list wrong size'
  86 try:
  87     a, b = l
  88     raise TestFailed
  89 except ValueError:
  90     pass
  91
  92
  93 # unpacking sequence too short
  94 if verbose:
  95     print 'unpack sequence too short'
  96 try:
  97     a, b, c, d = Seq()
  98     raise TestFailed
  99 except ValueError:
 100     pass
 101
 102
 103 # unpacking sequence too long
 104 if verbose:
 105     print 'unpack sequence too long'
 106 try:
 107     a, b = Seq()
 108     raise TestFailed
 109 except ValueError:
 110     pass
 111
 112
 113 # unpacking a sequence where the test for too long raises a different
 114 # kind of error
 115 class BozoError(Exception):
 116     pass
 117
 118 class BadSeq:
 119     def __getitem__(self, i):
 120         if i >= 0 and i < 3:
 121             return i
 122         elif i == 3:
 123             raise BozoError
 124         else:
 125             raise IndexError
 126
 127
 128 # trigger code while not expecting an IndexError
 129 if verbose:
 130     print 'unpack sequence too long, wrong error'
 131 try:
 132     a, b, c, d, e = BadSeq()
 133     raise TestFailed
 134 except BozoError:
 135     pass
 136
 137 # trigger code while expecting an IndexError
 138 if verbose:
 139     print 'unpack sequence too short, wrong error'
 140 try:
 141     a, b, c = BadSeq()
 142     raise TestFailed
 143 except BozoError:
 144     pass