mirror of https://github.com/python/cpython
42 lines
1.2 KiB
Python
42 lines
1.2 KiB
Python
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import functools
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import unittest
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from math import isnan, nextafter
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from test.support import requires_IEEE_754
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from test.support.hypothesis_helper import hypothesis
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floats = hypothesis.strategies.floats
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integers = hypothesis.strategies.integers
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def assert_equal_float(x, y):
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assert isnan(x) and isnan(y) or x == y
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def via_reduce(x, y, steps):
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return functools.reduce(nextafter, [y] * steps, x)
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class NextafterTests(unittest.TestCase):
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@requires_IEEE_754
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@hypothesis.given(
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x=floats(),
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y=floats(),
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steps=integers(min_value=0, max_value=2**16))
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def test_count(self, x, y, steps):
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assert_equal_float(via_reduce(x, y, steps),
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nextafter(x, y, steps=steps))
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@requires_IEEE_754
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@hypothesis.given(
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x=floats(),
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y=floats(),
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a=integers(min_value=0),
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b=integers(min_value=0))
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def test_addition_commutes(self, x, y, a, b):
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first = nextafter(x, y, steps=a)
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second = nextafter(first, y, steps=b)
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combined = nextafter(x, y, steps=a+b)
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hypothesis.note(f"{first} -> {second} == {combined}")
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assert_equal_float(second, combined)
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