91 lines
2.7 KiB
Python
91 lines
2.7 KiB
Python
from decimal import Decimal
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from math import fabs
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from typing import Any, Union, overload
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from hamcrest.core.base_matcher import BaseMatcher
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from hamcrest.core.description import Description
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from hamcrest.core.matcher import Matcher
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__author__ = "Jon Reid"
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__copyright__ = "Copyright 2011 hamcrest.org"
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__license__ = "BSD, see License.txt"
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Number = Union[float, Decimal] # Argh, https://github.com/python/mypy/issues/3186
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def isnumeric(value: Any) -> bool:
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"""Confirm that 'value' can be treated numerically; duck-test accordingly
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"""
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if isinstance(value, (float, complex, int)):
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return True
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try:
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_ = (fabs(value) + 0 - 0) * 1
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return True
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except ArithmeticError:
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return True
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except:
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return False
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class IsCloseTo(BaseMatcher[Number]):
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def __init__(self, value: Number, delta: Number) -> None:
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if not isnumeric(value):
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raise TypeError("IsCloseTo value must be numeric")
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if not isnumeric(delta):
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raise TypeError("IsCloseTo delta must be numeric")
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self.value = value
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self.delta = delta
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def _matches(self, item: Number) -> bool:
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if not isnumeric(item):
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return False
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return self._diff(item) <= self.delta
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def _diff(self, item: Number) -> float:
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# TODO - Fails for mixed floats & Decimals
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return fabs(item - self.value) # type: ignore
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def describe_mismatch(self, item: Number, mismatch_description: Description) -> None:
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if not isnumeric(item):
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super(IsCloseTo, self).describe_mismatch(item, mismatch_description)
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else:
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actual_delta = self._diff(item)
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mismatch_description.append_description_of(item).append_text(
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" differed by "
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).append_description_of(actual_delta)
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def describe_to(self, description: Description) -> None:
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description.append_text("a numeric value within ").append_description_of(
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self.delta
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).append_text(" of ").append_description_of(self.value)
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@overload
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def close_to(value: float, delta: float) -> Matcher[float]:
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...
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@overload
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def close_to(value: Decimal, delta: Decimal) -> Matcher[Decimal]:
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...
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def close_to(value, delta):
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"""Matches if object is a number close to a given value, within a given
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delta.
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:param value: The value to compare against as the expected value.
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:param delta: The maximum delta between the values for which the numbers
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are considered close.
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This matcher compares the evaluated object against ``value`` to see if the
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difference is within a positive ``delta``.
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Example::
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close_to(3.0, 0.25)
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"""
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return IsCloseTo(value, delta)
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