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