diff options
Diffstat (limited to 'Lib/test')
| -rw-r--r-- | Lib/test/test_pow.py | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/Lib/test/test_pow.py b/Lib/test/test_pow.py index 2c86b09..c6ab218 100644 --- a/Lib/test/test_pow.py +++ b/Lib/test/test_pow.py @@ -101,6 +101,23 @@ class PowTest(unittest.TestCase): return None None ** TestRpow() # Won't fail when __rpow__ invoked. SF bug #643260. + def test_bug705231(self): + # -1.0 raised to an integer should never blow up. It did if the + # platform pow() was buggy, and Python didn't worm around it. + eq = self.assertEquals + a = -1.0 + eq(pow(a, 1.23e167), 1.0) + eq(pow(a, -1.23e167), 1.0) + for b in range(-10, 11): + eq(pow(a, float(b)), b & 1 and -1.0 or 1.0) + for n in range(0, 100): + fiveto = float(5 ** n) + # For small n, fiveto will be odd. Eventually we run out of + # mantissa bits, though, and thereafer fiveto will be even. + expected = fiveto % 2.0 and -1.0 or 1.0 + eq(pow(a, fiveto), expected) + eq(pow(a, -fiveto), expected) + eq(expected, 1.0) # else we didn't push fiveto to evenness def test_main(): test.test_support.run_unittest(PowTest) |