Lib/test/test_pow.py

   1 import test.test_support, unittest
   2
   3 class PowTest(unittest.TestCase):
   4
   5     def powtest(self, type):
   6         if type != float:
   7             for i in range(-1000, 1000):
   8                 self.assertEquals(pow(type(i), 0), 1)
   9                 self.assertEquals(pow(type(i), 1), type(i))
  10                 self.assertEquals(pow(type(0), 1), type(0))
  11                 self.assertEquals(pow(type(1), 1), type(1))
  12
  13             for i in range(-100, 100):
  14                 self.assertEquals(pow(type(i), 3), i*i*i)
  15
  16             pow2 = 1
  17             for i in range(0,31):
  18                 self.assertEquals(pow(2, i), pow2)
  19                 if i != 30 : pow2 = pow2*2
  20
  21             for othertype in int, long:
  22                 for i in range(-10, 0) + range(1, 10):
  23                     ii = type(i)
  24                     for j in range(1, 11):
  25                         jj = -othertype(j)
  26                         pow(ii, jj)
  27
  28         for othertype in int, long, float:
  29             for i in range(1, 100):
  30                 zero = type(0)
  31                 exp = -othertype(i/10.0)
  32                 if exp == 0:
  33                     continue
  34                 self.assertRaises(ZeroDivisionError, pow, zero, exp)
  35
  36         il, ih = -20, 20
  37         jl, jh = -5,   5
  38         kl, kh = -10, 10
  39         asseq = self.assertEqual
  40         if type == float:
  41             il = 1
  42             asseq = self.assertAlmostEqual
  43         elif type == int:
  44             jl = 0
  45         elif type == long:
  46             jl, jh = 0, 15
  47         for i in range(il, ih+1):
  48             for j in range(jl, jh+1):
  49                 for k in range(kl, kh+1):
  50                     if k != 0:
  51                         if type == float or j < 0:
  52                             self.assertRaises(TypeError, pow, type(i), j, k)
  53                             continue
  54                         asseq(
  55                             pow(type(i),j,k),
  56                             pow(type(i),j)% type(k)
  57                         )
  58
  59     def test_powint(self):
  60         self.powtest(int)
  61
  62     def test_powlong(self):
  63         self.powtest(long)
  64
  65     def test_powfloat(self):
  66         self.powtest(float)
  67
  68     def test_other(self):
  69         # Other tests-- not very systematic
  70         self.assertEquals(pow(3,3) % 8, pow(3,3,8))
  71         self.assertEquals(pow(3,3) % -8, pow(3,3,-8))
  72         self.assertEquals(pow(3,2) % -2, pow(3,2,-2))
  73         self.assertEquals(pow(-3,3) % 8, pow(-3,3,8))
  74         self.assertEquals(pow(-3,3) % -8, pow(-3,3,-8))
  75         self.assertEquals(pow(5,2) % -8, pow(5,2,-8))
  76
  77         self.assertEquals(pow(3L,3L) % 8, pow(3L,3L,8))
  78         self.assertEquals(pow(3L,3L) % -8, pow(3L,3L,-8))
  79         self.assertEquals(pow(3L,2) % -2, pow(3L,2,-2))
  80         self.assertEquals(pow(-3L,3L) % 8, pow(-3L,3L,8))
  81         self.assertEquals(pow(-3L,3L) % -8, pow(-3L,3L,-8))
  82         self.assertEquals(pow(5L,2) % -8, pow(5L,2,-8))
  83
  84         for i in range(-10, 11):
  85             for j in range(0, 6):
  86                 for k in range(-7, 11):
  87                     if j >= 0 and k != 0:
  88                         self.assertEquals(
  89                             pow(i,j) % k,
  90                             pow(i,j,k)
  91                         )
  92                     if j >= 0 and k != 0:
  93                         self.assertEquals(
  94                             pow(long(i),j) % k,
  95                             pow(long(i),j,k)
  96                         )
  97
  98     def test_bug643260(self):
  99         class TestRpow:
 100             def __rpow__(self, other):
 101                 return None
 102         None ** TestRpow() # Won't fail when __rpow__ invoked.  SF bug #643260.
 103
 104     def test_bug705231(self):
 105         # -1.0 raised to an integer should never blow up.  It did if the
 106         # platform pow() was buggy, and Python didn't worm around it.
 107         eq = self.assertEquals
 108         a = -1.0
 109         # The next two tests can still fail if the platform floor()
 110         # function doesn't treat all large inputs as integers
 111         # test_math should also fail if that is happening
 112         eq(pow(a, 1.23e167), 1.0)
 113         eq(pow(a, -1.23e167), 1.0)
 114         for b in range(-10, 11):
 115             eq(pow(a, float(b)), b & 1 and -1.0 or 1.0)
 116         for n in range(0, 100):
 117             fiveto = float(5 ** n)
 118             # For small n, fiveto will be odd.  Eventually we run out of
 119             # mantissa bits, though, and thereafer fiveto will be even.
 120             expected = fiveto % 2.0 and -1.0 or 1.0
 121             eq(pow(a, fiveto), expected)
 122             eq(pow(a, -fiveto), expected)
 123         eq(expected, 1.0)   # else we didn't push fiveto to evenness
 124
 125 def test_main():
 126     test.test_support.run_unittest(PowTest)
 127
 128 if __name__ == "__main__":
 129     test_main()