diff options
Diffstat (limited to 'Lib/test/test_float.py')
| -rw-r--r-- | Lib/test/test_float.py | 140 |
1 files changed, 139 insertions, 1 deletions
diff --git a/Lib/test/test_float.py b/Lib/test/test_float.py index 86dae3f690..573cc7e6e1 100644 --- a/Lib/test/test_float.py +++ b/Lib/test/test_float.py @@ -5,7 +5,9 @@ from test import test_support import math from math import isinf, isnan, copysign, ldexp import operator -import random, fractions +import random +import fractions +import sys INF = float("inf") NAN = float("nan") @@ -339,6 +341,141 @@ class ReprTestCase(unittest.TestCase): self.assertEqual(v, eval(repr(v))) floats_file.close() +@unittest.skipUnless(float.__getformat__("double").startswith("IEEE"), + "test requires IEEE 754 doubles") +class RoundTestCase(unittest.TestCase): + def test_second_argument_type(self): + # any type with an __index__ method should be permitted as + # a second argument + self.assertAlmostEqual(round(12.34, True), 12.3) + + class MyIndex(object): + def __index__(self): return 4 + self.assertAlmostEqual(round(-0.123456, MyIndex()), -0.1235) + # but floats should be illegal + self.assertRaises(TypeError, round, 3.14159, 2.0) + + def test_inf_nan(self): + # rounding an infinity or nan returns the same number; + # (in py3k, rounding an infinity or nan raises an error, + # since the result can't be represented as a long). + self.assertEqual(round(INF), INF) + self.assertEqual(round(-INF), -INF) + self.assertTrue(math.isnan(round(NAN))) + for n in range(-5, 5): + self.assertEqual(round(INF, n), INF) + self.assertEqual(round(-INF, n), -INF) + self.assertTrue(math.isnan(round(NAN, n))) + + def test_large_n(self): + for n in [324, 325, 400, 2**31-1, 2**31, 2**32, 2**100]: + self.assertEqual(round(123.456, n), 123.456) + self.assertEqual(round(-123.456, n), -123.456) + self.assertEqual(round(1e300, n), 1e300) + self.assertEqual(round(1e-320, n), 1e-320) + self.assertEqual(round(1e150, 300), 1e150) + self.assertEqual(round(1e300, 307), 1e300) + self.assertEqual(round(-3.1415, 308), -3.1415) + self.assertEqual(round(1e150, 309), 1e150) + self.assertEqual(round(1.4e-315, 315), 1e-315) + + def test_small_n(self): + for n in [-308, -309, -400, 1-2**31, -2**31, -2**31-1, -2**100]: + self.assertEqual(round(123.456, n), 0.0) + self.assertEqual(round(-123.456, n), -0.0) + self.assertEqual(round(1e300, n), 0.0) + self.assertEqual(round(1e-320, n), 0.0) + + def test_overflow(self): + self.assertRaises(OverflowError, round, 1.6e308, -308) + self.assertRaises(OverflowError, round, -1.7e308, -308) + + @unittest.skipUnless(getattr(sys, 'float_repr_style', '') == 'short', + "test applies only when using short float repr style") + def test_previous_round_bugs(self): + # particular cases that have occurred in bug reports + self.assertEqual(round(562949953421312.5, 1), + 562949953421312.5) + self.assertEqual(round(56294995342131.5, 3), + 56294995342131.5) + + @unittest.skipUnless(getattr(sys, 'float_repr_style', '') == 'short', + "test applies only when using short float repr style") + def test_halfway_cases(self): + # Halfway cases need special attention, since the current + # implementation has to deal with them specially. Note that + # 2.x rounds halfway values up (i.e., away from zero) while + # 3.x does round-half-to-even. + self.assertAlmostEqual(round(0.125, 2), 0.13) + self.assertAlmostEqual(round(0.375, 2), 0.38) + self.assertAlmostEqual(round(0.625, 2), 0.63) + self.assertAlmostEqual(round(0.875, 2), 0.88) + self.assertAlmostEqual(round(-0.125, 2), -0.13) + self.assertAlmostEqual(round(-0.375, 2), -0.38) + self.assertAlmostEqual(round(-0.625, 2), -0.63) + self.assertAlmostEqual(round(-0.875, 2), -0.88) + + self.assertAlmostEqual(round(0.25, 1), 0.3) + self.assertAlmostEqual(round(0.75, 1), 0.8) + self.assertAlmostEqual(round(-0.25, 1), -0.3) + self.assertAlmostEqual(round(-0.75, 1), -0.8) + + self.assertEqual(round(-6.5, 0), -7.0) + self.assertEqual(round(-5.5, 0), -6.0) + self.assertEqual(round(-1.5, 0), -2.0) + self.assertEqual(round(-0.5, 0), -1.0) + self.assertEqual(round(0.5, 0), 1.0) + self.assertEqual(round(1.5, 0), 2.0) + self.assertEqual(round(2.5, 0), 3.0) + self.assertEqual(round(3.5, 0), 4.0) + self.assertEqual(round(4.5, 0), 5.0) + self.assertEqual(round(5.5, 0), 6.0) + self.assertEqual(round(6.5, 0), 7.0) + + # same but without an explicit second argument; in 3.x these + # will give integers + self.assertEqual(round(-6.5), -7.0) + self.assertEqual(round(-5.5), -6.0) + self.assertEqual(round(-1.5), -2.0) + self.assertEqual(round(-0.5), -1.0) + self.assertEqual(round(0.5), 1.0) + self.assertEqual(round(1.5), 2.0) + self.assertEqual(round(2.5), 3.0) + self.assertEqual(round(3.5), 4.0) + self.assertEqual(round(4.5), 5.0) + self.assertEqual(round(5.5), 6.0) + self.assertEqual(round(6.5), 7.0) + + self.assertEqual(round(-25.0, -1), -30.0) + self.assertEqual(round(-15.0, -1), -20.0) + self.assertEqual(round(-5.0, -1), -10.0) + self.assertEqual(round(5.0, -1), 10.0) + self.assertEqual(round(15.0, -1), 20.0) + self.assertEqual(round(25.0, -1), 30.0) + self.assertEqual(round(35.0, -1), 40.0) + self.assertEqual(round(45.0, -1), 50.0) + self.assertEqual(round(55.0, -1), 60.0) + self.assertEqual(round(65.0, -1), 70.0) + self.assertEqual(round(75.0, -1), 80.0) + self.assertEqual(round(85.0, -1), 90.0) + self.assertEqual(round(95.0, -1), 100.0) + self.assertEqual(round(12325.0, -1), 12330.0) + + self.assertEqual(round(350.0, -2), 400.0) + self.assertEqual(round(450.0, -2), 500.0) + + self.assertAlmostEqual(round(0.5e21, -21), 1e21) + self.assertAlmostEqual(round(1.5e21, -21), 2e21) + self.assertAlmostEqual(round(2.5e21, -21), 3e21) + self.assertAlmostEqual(round(5.5e21, -21), 6e21) + self.assertAlmostEqual(round(8.5e21, -21), 9e21) + + self.assertAlmostEqual(round(-1.5e22, -22), -2e22) + self.assertAlmostEqual(round(-0.5e22, -22), -1e22) + self.assertAlmostEqual(round(0.5e22, -22), 1e22) + self.assertAlmostEqual(round(1.5e22, -22), 2e22) + + # Beginning with Python 2.6 float has cross platform compatible # ways to create and represent inf and nan class InfNanTest(unittest.TestCase): @@ -859,6 +996,7 @@ def test_main(): UnknownFormatTestCase, IEEEFormatTestCase, ReprTestCase, + RoundTestCase, InfNanTest, HexFloatTestCase, ) |