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| # mypy: allow-untyped-defs | |
| from __future__ import annotations | |
| import builtins | |
| from collections.abc import Collection | |
| from collections.abc import Mapping | |
| from collections.abc import Sequence | |
| from collections.abc import Sized | |
| from datetime import datetime | |
| from datetime import timedelta | |
| from decimal import Decimal | |
| import math | |
| from numbers import Complex | |
| import pprint | |
| import sys | |
| from typing import Any | |
| from typing import TYPE_CHECKING | |
| if TYPE_CHECKING: | |
| from numpy import ndarray | |
| def _compare_approx( | |
| full_object: object, | |
| message_data: Sequence[tuple[str, str, str]], | |
| number_of_elements: int, | |
| different_ids: Sequence[object], | |
| max_abs_diff: float, | |
| max_rel_diff: float, | |
| ) -> list[str]: | |
| message_list = list(message_data) | |
| message_list.insert(0, ("Index", "Obtained", "Expected")) | |
| max_sizes = [0, 0, 0] | |
| for index, obtained, expected in message_list: | |
| max_sizes[0] = max(max_sizes[0], len(index)) | |
| max_sizes[1] = max(max_sizes[1], len(obtained)) | |
| max_sizes[2] = max(max_sizes[2], len(expected)) | |
| explanation = [ | |
| f"comparison failed. Mismatched elements: {len(different_ids)} / {number_of_elements}:", | |
| f"Max absolute difference: {max_abs_diff}", | |
| f"Max relative difference: {max_rel_diff}", | |
| ] + [ | |
| f"{indexes:<{max_sizes[0]}} | {obtained:<{max_sizes[1]}} | {expected:<{max_sizes[2]}}" | |
| for indexes, obtained, expected in message_list | |
| ] | |
| return explanation | |
| # builtin pytest.approx helper | |
| class ApproxBase: | |
| """Provide shared utilities for making approximate comparisons between | |
| numbers or sequences of numbers.""" | |
| # Tell numpy to use our `__eq__` operator instead of its. | |
| __array_ufunc__ = None | |
| __array_priority__ = 100 | |
| def __init__(self, expected, rel=None, abs=None, nan_ok: bool = False) -> None: | |
| __tracebackhide__ = True | |
| self.expected = expected | |
| self.abs = abs | |
| self.rel = rel | |
| self.nan_ok = nan_ok | |
| self._check_type() | |
| def __repr__(self) -> str: | |
| raise NotImplementedError | |
| def _repr_compare(self, other_side: Any) -> list[str]: | |
| return [ | |
| "comparison failed", | |
| f"Obtained: {other_side}", | |
| f"Expected: {self}", | |
| ] | |
| def __eq__(self, actual) -> bool: | |
| return all( | |
| a == self._approx_scalar(x) for a, x in self._yield_comparisons(actual) | |
| ) | |
| def __bool__(self): | |
| __tracebackhide__ = True | |
| raise AssertionError( | |
| "approx() is not supported in a boolean context.\nDid you mean: `assert a == approx(b)`?" | |
| ) | |
| # Ignore type because of https://github.com/python/mypy/issues/4266. | |
| __hash__ = None # type: ignore | |
| def __ne__(self, actual) -> bool: | |
| return not (actual == self) | |
| def _approx_scalar(self, x) -> ApproxBase: | |
| if isinstance(x, Decimal): | |
| return ApproxDecimal(x, rel=self.rel, abs=self.abs, nan_ok=self.nan_ok) | |
| if isinstance(x, (datetime, timedelta)): | |
| return ApproxTimedelta(x, rel=self.rel, abs=self.abs, nan_ok=self.nan_ok) | |
| return ApproxScalar(x, rel=self.rel, abs=self.abs, nan_ok=self.nan_ok) | |
| def _yield_comparisons(self, actual): | |
| """Yield all the pairs of numbers to be compared. | |
| This is used to implement the `__eq__` method. | |
| """ | |
| raise NotImplementedError | |
| def _check_type(self) -> None: | |
| """Raise a TypeError if the expected value is not a valid type.""" | |
| # This is only a concern if the expected value is a sequence. In every | |
| # other case, the approx() function ensures that the expected value has | |
| # a numeric type. For this reason, the default is to do nothing. The | |
| # classes that deal with sequences should reimplement this method to | |
| # raise if there are any non-numeric elements in the sequence. | |
| def _recursive_sequence_map(f, x): | |
| """Recursively map a function over a sequence of arbitrary depth""" | |
| if isinstance(x, list | tuple): | |
| seq_type = type(x) | |
| return seq_type(_recursive_sequence_map(f, xi) for xi in x) | |
| elif _is_sequence_like(x): | |
| return [_recursive_sequence_map(f, xi) for xi in x] | |
| else: | |
| return f(x) | |
| class ApproxNumpy(ApproxBase): | |
| """Perform approximate comparisons where the expected value is numpy array.""" | |
| def __repr__(self) -> str: | |
| list_scalars = _recursive_sequence_map( | |
| self._approx_scalar, self.expected.tolist() | |
| ) | |
| return f"approx({list_scalars!r})" | |
| def _repr_compare(self, other_side: ndarray | list[Any]) -> list[str]: | |
| import itertools | |
| import math | |
| def get_value_from_nested_list( | |
| nested_list: list[Any], nd_index: tuple[Any, ...] | |
| ) -> Any: | |
| """ | |
| Helper function to get the value out of a nested list, given an n-dimensional index. | |
| This mimics numpy's indexing, but for raw nested python lists. | |
| """ | |
| value: Any = nested_list | |
| for i in nd_index: | |
| value = value[i] | |
| return value | |
| np_array_shape = self.expected.shape | |
| approx_side_as_seq = _recursive_sequence_map( | |
| self._approx_scalar, self.expected.tolist() | |
| ) | |
| # convert other_side to numpy array to ensure shape attribute is available | |
| other_side_as_array = _as_numpy_array(other_side) | |
| assert other_side_as_array is not None | |
| if np_array_shape != other_side_as_array.shape: | |
| return [ | |
| "Impossible to compare arrays with different shapes.", | |
| f"Shapes: {np_array_shape} and {other_side_as_array.shape}", | |
| ] | |
| number_of_elements = self.expected.size | |
| max_abs_diff = -math.inf | |
| max_rel_diff = -math.inf | |
| different_ids = [] | |
| for index in itertools.product(*(range(i) for i in np_array_shape)): | |
| approx_value = get_value_from_nested_list(approx_side_as_seq, index) | |
| other_value = get_value_from_nested_list(other_side_as_array, index) | |
| if approx_value != other_value: | |
| abs_diff = abs(approx_value.expected - other_value) | |
| max_abs_diff = max(max_abs_diff, abs_diff) | |
| if other_value == 0.0: | |
| max_rel_diff = math.inf | |
| else: | |
| max_rel_diff = max(max_rel_diff, abs_diff / abs(other_value)) | |
| different_ids.append(index) | |
| message_data = [ | |
| ( | |
| str(index), | |
| str(get_value_from_nested_list(other_side_as_array, index)), | |
| str(get_value_from_nested_list(approx_side_as_seq, index)), | |
| ) | |
| for index in different_ids | |
| ] | |
| return _compare_approx( | |
| self.expected, | |
| message_data, | |
| number_of_elements, | |
| different_ids, | |
| max_abs_diff, | |
| max_rel_diff, | |
| ) | |
| def __eq__(self, actual) -> bool: | |
| import numpy as np | |
| # self.expected is supposed to always be an array here. | |
| if not np.isscalar(actual): | |
| try: | |
| actual = np.asarray(actual) | |
| except Exception as e: | |
| raise TypeError(f"cannot compare '{actual}' to numpy.ndarray") from e | |
| if not np.isscalar(actual) and actual.shape != self.expected.shape: | |
| return False | |
| return super().__eq__(actual) | |
| def _yield_comparisons(self, actual): | |
| import numpy as np | |
| # `actual` can either be a numpy array or a scalar, it is treated in | |
| # `__eq__` before being passed to `ApproxBase.__eq__`, which is the | |
| # only method that calls this one. | |
| if np.isscalar(actual): | |
| for i in np.ndindex(self.expected.shape): | |
| yield actual, self.expected[i].item() | |
| else: | |
| for i in np.ndindex(self.expected.shape): | |
| yield actual[i].item(), self.expected[i].item() | |
| class ApproxMapping(ApproxBase): | |
| """Perform approximate comparisons where the expected value is a mapping | |
| with numeric values (the keys can be anything).""" | |
| def __repr__(self) -> str: | |
| return f"approx({ ({k: self._approx_scalar(v) for k, v in self.expected.items()})!r})" | |
| def _repr_compare(self, other_side: Mapping[object, float]) -> list[str]: | |
| import math | |
| if len(self.expected) != len(other_side): | |
| return [ | |
| "Impossible to compare mappings with different sizes.", | |
| f"Lengths: {len(self.expected)} and {len(other_side)}", | |
| ] | |
| if self.expected.keys() != other_side.keys(): | |
| return [ | |
| "comparison failed.", | |
| f"Mappings has different keys: expected {self.expected.keys()} but got {other_side.keys()}", | |
| ] | |
| approx_side_as_map = { | |
| k: self._approx_scalar(v) for k, v in self.expected.items() | |
| } | |
| number_of_elements = len(approx_side_as_map) | |
| max_abs_diff = -math.inf | |
| max_rel_diff = -math.inf | |
| different_ids = [] | |
| for approx_key, approx_value in approx_side_as_map.items(): | |
| other_value = other_side[approx_key] | |
| if approx_value != other_value: | |
| if approx_value.expected is not None and other_value is not None: | |
| try: | |
| max_abs_diff = max( | |
| max_abs_diff, abs(approx_value.expected - other_value) | |
| ) | |
| if approx_value.expected == 0.0: | |
| max_rel_diff = math.inf | |
| else: | |
| max_rel_diff = max( | |
| max_rel_diff, | |
| abs( | |
| (approx_value.expected - other_value) | |
| / approx_value.expected | |
| ), | |
| ) | |
| except ZeroDivisionError: | |
| pass | |
| different_ids.append(approx_key) | |
| message_data = [ | |
| (str(key), str(other_side[key]), str(approx_side_as_map[key])) | |
| for key in different_ids | |
| ] | |
| return _compare_approx( | |
| self.expected, | |
| message_data, | |
| number_of_elements, | |
| different_ids, | |
| max_abs_diff, | |
| max_rel_diff, | |
| ) | |
| def __eq__(self, actual) -> bool: | |
| try: | |
| if set(actual.keys()) != set(self.expected.keys()): | |
| return False | |
| except AttributeError: | |
| return False | |
| return super().__eq__(actual) | |
| def _yield_comparisons(self, actual): | |
| for k in self.expected.keys(): | |
| yield actual[k], self.expected[k] | |
| def _check_type(self) -> None: | |
| __tracebackhide__ = True | |
| for key, value in self.expected.items(): | |
| if isinstance(value, type(self.expected)): | |
| msg = "pytest.approx() does not support nested dictionaries: key={!r} value={!r}\n full mapping={}" | |
| raise TypeError(msg.format(key, value, pprint.pformat(self.expected))) | |
| class ApproxSequenceLike(ApproxBase): | |
| """Perform approximate comparisons where the expected value is a sequence of numbers.""" | |
| def __repr__(self) -> str: | |
| seq_type = type(self.expected) | |
| if seq_type not in (tuple, list): | |
| seq_type = list | |
| return f"approx({seq_type(self._approx_scalar(x) for x in self.expected)!r})" | |
| def _repr_compare(self, other_side: Sequence[float]) -> list[str]: | |
| import math | |
| if len(self.expected) != len(other_side): | |
| return [ | |
| "Impossible to compare lists with different sizes.", | |
| f"Lengths: {len(self.expected)} and {len(other_side)}", | |
| ] | |
| approx_side_as_map = _recursive_sequence_map(self._approx_scalar, self.expected) | |
| number_of_elements = len(approx_side_as_map) | |
| max_abs_diff = -math.inf | |
| max_rel_diff = -math.inf | |
| different_ids = [] | |
| for i, (approx_value, other_value) in enumerate( | |
| zip(approx_side_as_map, other_side, strict=True) | |
| ): | |
| if approx_value != other_value: | |
| try: | |
| abs_diff = abs(approx_value.expected - other_value) | |
| max_abs_diff = max(max_abs_diff, abs_diff) | |
| # Ignore non-numbers for the diff calculations (#13012). | |
| except TypeError: | |
| pass | |
| else: | |
| if other_value == 0.0: | |
| max_rel_diff = math.inf | |
| else: | |
| max_rel_diff = max(max_rel_diff, abs_diff / abs(other_value)) | |
| different_ids.append(i) | |
| message_data = [ | |
| (str(i), str(other_side[i]), str(approx_side_as_map[i])) | |
| for i in different_ids | |
| ] | |
| return _compare_approx( | |
| self.expected, | |
| message_data, | |
| number_of_elements, | |
| different_ids, | |
| max_abs_diff, | |
| max_rel_diff, | |
| ) | |
| def __eq__(self, actual) -> bool: | |
| try: | |
| if len(actual) != len(self.expected): | |
| return False | |
| except TypeError: | |
| return False | |
| return super().__eq__(actual) | |
| def _yield_comparisons(self, actual): | |
| return zip(actual, self.expected, strict=True) | |
| def _check_type(self) -> None: | |
| __tracebackhide__ = True | |
| for index, x in enumerate(self.expected): | |
| if isinstance(x, type(self.expected)): | |
| msg = "pytest.approx() does not support nested data structures: {!r} at index {}\n full sequence: {}" | |
| raise TypeError(msg.format(x, index, pprint.pformat(self.expected))) | |
| class ApproxScalar(ApproxBase): | |
| """Perform approximate comparisons where the expected value is a single number.""" | |
| # Using Real should be better than this Union, but not possible yet: | |
| # https://github.com/python/typeshed/pull/3108 | |
| DEFAULT_ABSOLUTE_TOLERANCE: float | Decimal = 1e-12 | |
| DEFAULT_RELATIVE_TOLERANCE: float | Decimal = 1e-6 | |
| def __repr__(self) -> str: | |
| """Return a string communicating both the expected value and the | |
| tolerance for the comparison being made. | |
| For example, ``1.0 ± 1e-6``, ``(3+4j) ± 5e-6 ∠ ±180°``. | |
| """ | |
| # Don't show a tolerance for values that aren't compared using | |
| # tolerances, i.e. non-numerics and infinities. Need to call abs to | |
| # handle complex numbers, e.g. (inf + 1j). | |
| if ( | |
| isinstance(self.expected, bool) | |
| or (not isinstance(self.expected, Complex | Decimal)) | |
| or math.isinf(abs(self.expected) or isinstance(self.expected, bool)) | |
| ): | |
| return str(self.expected) | |
| # If a sensible tolerance can't be calculated, self.tolerance will | |
| # raise a ValueError. In this case, display '???'. | |
| try: | |
| if 1e-3 <= self.tolerance < 1e3: | |
| vetted_tolerance = f"{self.tolerance:n}" | |
| else: | |
| vetted_tolerance = f"{self.tolerance:.1e}" | |
| if ( | |
| isinstance(self.expected, Complex) | |
| and self.expected.imag | |
| and not math.isinf(self.tolerance) | |
| ): | |
| vetted_tolerance += " ∠ ±180°" | |
| except ValueError: | |
| vetted_tolerance = "???" | |
| return f"{self.expected} ± {vetted_tolerance}" | |
| def __eq__(self, actual) -> bool: | |
| """Return whether the given value is equal to the expected value | |
| within the pre-specified tolerance.""" | |
| def is_bool(val: Any) -> bool: | |
| # Check if `val` is a native bool or numpy bool. | |
| if isinstance(val, bool): | |
| return True | |
| if np := sys.modules.get("numpy"): | |
| return isinstance(val, np.bool_) | |
| return False | |
| asarray = _as_numpy_array(actual) | |
| if asarray is not None: | |
| # Call ``__eq__()`` manually to prevent infinite-recursion with | |
| # numpy<1.13. See #3748. | |
| return all(self.__eq__(a) for a in asarray.flat) | |
| # Short-circuit exact equality, except for bool and np.bool_ | |
| if is_bool(self.expected) and not is_bool(actual): | |
| return False | |
| elif actual == self.expected: | |
| return True | |
| # If either type is non-numeric, fall back to strict equality. | |
| # NB: we need Complex, rather than just Number, to ensure that __abs__, | |
| # __sub__, and __float__ are defined. Also, consider bool to be | |
| # non-numeric, even though it has the required arithmetic. | |
| if is_bool(self.expected) or not ( | |
| isinstance(self.expected, Complex | Decimal) | |
| and isinstance(actual, Complex | Decimal) | |
| ): | |
| return False | |
| # Allow the user to control whether NaNs are considered equal to each | |
| # other or not. The abs() calls are for compatibility with complex | |
| # numbers. | |
| if math.isnan(abs(self.expected)): | |
| return self.nan_ok and math.isnan(abs(actual)) | |
| # Infinity shouldn't be approximately equal to anything but itself, but | |
| # if there's a relative tolerance, it will be infinite and infinity | |
| # will seem approximately equal to everything. The equal-to-itself | |
| # case would have been short circuited above, so here we can just | |
| # return false if the expected value is infinite. The abs() call is | |
| # for compatibility with complex numbers. | |
| if math.isinf(abs(self.expected)): | |
| return False | |
| # Return true if the two numbers are within the tolerance. | |
| result: bool = abs(self.expected - actual) <= self.tolerance | |
| return result | |
| __hash__ = None | |
| def tolerance(self): | |
| """Return the tolerance for the comparison. | |
| This could be either an absolute tolerance or a relative tolerance, | |
| depending on what the user specified or which would be larger. | |
| """ | |
| def set_default(x, default): | |
| return x if x is not None else default | |
| # Figure out what the absolute tolerance should be. ``self.abs`` is | |
| # either None or a value specified by the user. | |
| absolute_tolerance = set_default(self.abs, self.DEFAULT_ABSOLUTE_TOLERANCE) | |
| if absolute_tolerance < 0: | |
| raise ValueError( | |
| f"absolute tolerance can't be negative: {absolute_tolerance}" | |
| ) | |
| if math.isnan(absolute_tolerance): | |
| raise ValueError("absolute tolerance can't be NaN.") | |
| # If the user specified an absolute tolerance but not a relative one, | |
| # just return the absolute tolerance. | |
| if self.rel is None: | |
| if self.abs is not None: | |
| return absolute_tolerance | |
| # Figure out what the relative tolerance should be. ``self.rel`` is | |
| # either None or a value specified by the user. This is done after | |
| # we've made sure the user didn't ask for an absolute tolerance only, | |
| # because we don't want to raise errors about the relative tolerance if | |
| # we aren't even going to use it. | |
| relative_tolerance = set_default( | |
| self.rel, self.DEFAULT_RELATIVE_TOLERANCE | |
| ) * abs(self.expected) | |
| if relative_tolerance < 0: | |
| raise ValueError( | |
| f"relative tolerance can't be negative: {relative_tolerance}" | |
| ) | |
| if math.isnan(relative_tolerance): | |
| raise ValueError("relative tolerance can't be NaN.") | |
| # Return the larger of the relative and absolute tolerances. | |
| return max(relative_tolerance, absolute_tolerance) | |
| class ApproxDecimal(ApproxScalar): | |
| """Perform approximate comparisons where the expected value is a Decimal.""" | |
| DEFAULT_ABSOLUTE_TOLERANCE = Decimal("1e-12") | |
| DEFAULT_RELATIVE_TOLERANCE = Decimal("1e-6") | |
| def __repr__(self) -> str: | |
| if isinstance(self.rel, float): | |
| rel = Decimal.from_float(self.rel) | |
| else: | |
| rel = self.rel | |
| if isinstance(self.abs, float): | |
| abs_ = Decimal.from_float(self.abs) | |
| else: | |
| abs_ = self.abs | |
| tol_str = "???" | |
| if rel is not None and Decimal("1e-3") <= rel <= Decimal("1e3"): | |
| tol_str = f"{rel:.1e}" | |
| elif abs_ is not None: | |
| tol_str = f"{abs_:.1e}" | |
| return f"{self.expected} ± {tol_str}" | |
| class ApproxTimedelta(ApproxBase): | |
| """Perform approximate comparisons where the expected value is a | |
| datetime or timedelta. | |
| Requires an explicit tolerance as a timedelta for abs, or a float for rel. | |
| Relative tolerance is not supported for datetime comparisons. | |
| """ | |
| def __init__(self, expected, rel=None, abs=None, nan_ok: bool = False) -> None: | |
| __tracebackhide__ = True | |
| if isinstance(expected, datetime) and rel is not None: | |
| raise TypeError( | |
| "pytest.approx() does not support relative tolerance for " | |
| "datetime comparisons. Use abs=timedelta(...) instead." | |
| ) | |
| if nan_ok: | |
| raise TypeError( | |
| "pytest.approx() does not support nan_ok for " | |
| "datetime/timedelta comparisons." | |
| ) | |
| if abs is None and rel is None: | |
| raise TypeError( | |
| "pytest.approx() requires an explicit tolerance for " | |
| "datetime/timedelta comparisons: " | |
| "e.g. approx(expected, abs=timedelta(seconds=1)) " | |
| "or approx(expected, rel=0.01)" | |
| ) | |
| if abs is not None and not isinstance(abs, timedelta): | |
| raise TypeError( | |
| f"absolute tolerance for datetime/timedelta must be a " | |
| f"timedelta, got {type(abs).__name__}" | |
| ) | |
| if abs is not None and abs < timedelta(0): | |
| raise ValueError(f"absolute tolerance can't be negative: {abs}") | |
| if rel is not None: | |
| if not isinstance(rel, (int, float)): | |
| raise TypeError( | |
| f"relative tolerance for timedelta must be a " | |
| f"number, got {type(rel).__name__}" | |
| ) | |
| if rel < 0: | |
| raise ValueError(f"relative tolerance can't be negative: {rel}") | |
| if math.isnan(rel): | |
| raise ValueError("relative tolerance can't be NaN.") | |
| # Compute the effective tolerance. abs_tolerance is a timedelta, rel * expected | |
| # gives a timedelta (timedelta * float works in Python). | |
| abs_tolerance = abs | |
| rel_tolerance = rel * builtins.abs(expected) if rel is not None else None | |
| if abs_tolerance is not None and rel_tolerance is not None: | |
| tolerance = max(abs_tolerance, rel_tolerance) | |
| else: | |
| tolerance = abs_tolerance if abs_tolerance is not None else rel_tolerance | |
| super().__init__(expected, rel=rel, abs=tolerance, nan_ok=False) | |
| def __repr__(self) -> str: | |
| return f"{self.expected} ± {self.abs}" | |
| def __eq__(self, actual) -> bool: | |
| try: | |
| return bool(builtins.abs(self.expected - actual) <= self.abs) | |
| except (TypeError, OverflowError): | |
| return False | |
| def _yield_comparisons(self, actual): | |
| yield actual, self.expected | |
| def _repr_compare(self, other_side: Any) -> list[str]: | |
| try: | |
| abs_diff = builtins.abs(self.expected - other_side) | |
| except (TypeError, OverflowError): | |
| abs_diff = "N/A" | |
| return [ | |
| "comparison failed", | |
| f"Obtained: {other_side}", | |
| f"Expected: {self.expected} ± {self.abs}", | |
| f"Absolute difference: {abs_diff}", | |
| f"Tolerance: {self.abs}", | |
| ] | |
| def approx( | |
| expected: Any, | |
| rel: float | Decimal | timedelta | None = None, | |
| abs: float | Decimal | timedelta | None = None, | |
| nan_ok: bool = False, | |
| ) -> ApproxBase: | |
| """Assert that two numbers (or two ordered sequences of numbers) are equal to each other | |
| within some tolerance. | |
| Due to the :doc:`python:tutorial/floatingpoint`, numbers that we | |
| would intuitively expect to be equal are not always so:: | |
| >>> 0.1 + 0.2 == 0.3 | |
| False | |
| This problem is commonly encountered when writing tests, e.g. when making | |
| sure that floating-point values are what you expect them to be. One way to | |
| deal with this problem is to assert that two floating-point numbers are | |
| equal to within some appropriate tolerance:: | |
| >>> abs((0.1 + 0.2) - 0.3) < 1e-6 | |
| True | |
| However, comparisons like this are tedious to write and difficult to | |
| understand. Furthermore, absolute comparisons like the one above are | |
| usually discouraged because there's no tolerance that works well for all | |
| situations. ``1e-6`` is good for numbers around ``1``, but too small for | |
| very big numbers and too big for very small ones. It's better to express | |
| the tolerance as a fraction of the expected value, but relative comparisons | |
| like that are even more difficult to write correctly and concisely. | |
| The ``approx`` class performs floating-point comparisons using a syntax | |
| that's as intuitive as possible:: | |
| >>> from pytest import approx | |
| >>> 0.1 + 0.2 == approx(0.3) | |
| True | |
| The same syntax also works for ordered sequences of numbers:: | |
| >>> (0.1 + 0.2, 0.2 + 0.4) == approx((0.3, 0.6)) | |
| True | |
| ``numpy`` arrays:: | |
| >>> import numpy as np # doctest: +SKIP | |
| >>> np.array([0.1, 0.2]) + np.array([0.2, 0.4]) == approx(np.array([0.3, 0.6])) # doctest: +SKIP | |
| True | |
| And for a ``numpy`` array against a scalar:: | |
| >>> import numpy as np # doctest: +SKIP | |
| >>> np.array([0.1, 0.2]) + np.array([0.2, 0.1]) == approx(0.3) # doctest: +SKIP | |
| True | |
| Only ordered sequences are supported, because ``approx`` needs | |
| to infer the relative position of the sequences without ambiguity. This means | |
| ``sets`` and other unordered sequences are not supported. | |
| Finally, dictionary *values* can also be compared:: | |
| >>> {'a': 0.1 + 0.2, 'b': 0.2 + 0.4} == approx({'a': 0.3, 'b': 0.6}) | |
| True | |
| The comparison will be true if both mappings have the same keys and their | |
| respective values match the expected tolerances. | |
| **Tolerances** | |
| By default, ``approx`` considers numbers within a relative tolerance of | |
| ``1e-6`` (i.e. one part in a million) of its expected value to be equal. | |
| This treatment would lead to surprising results if the expected value was | |
| ``0.0``, because nothing but ``0.0`` itself is relatively close to ``0.0``. | |
| To handle this case less surprisingly, ``approx`` also considers numbers | |
| within an absolute tolerance of ``1e-12`` of its expected value to be | |
| equal. Infinity and NaN are special cases. Infinity is only considered | |
| equal to itself, regardless of the relative tolerance. NaN is not | |
| considered equal to anything by default, but you can make it be equal to | |
| itself by setting the ``nan_ok`` argument to True. (This is meant to | |
| facilitate comparing arrays that use NaN to mean "no data".) | |
| Both the relative and absolute tolerances can be changed by passing | |
| arguments to the ``approx`` constructor:: | |
| >>> 1.0001 == approx(1) | |
| False | |
| >>> 1.0001 == approx(1, rel=1e-3) | |
| True | |
| >>> 1.0001 == approx(1, abs=1e-3) | |
| True | |
| If you specify ``abs`` but not ``rel``, the comparison will not consider | |
| the relative tolerance at all. In other words, two numbers that are within | |
| the default relative tolerance of ``1e-6`` will still be considered unequal | |
| if they exceed the specified absolute tolerance. If you specify both | |
| ``abs`` and ``rel``, the numbers will be considered equal if either | |
| tolerance is met:: | |
| >>> 1 + 1e-8 == approx(1) | |
| True | |
| >>> 1 + 1e-8 == approx(1, abs=1e-12) | |
| False | |
| >>> 1 + 1e-8 == approx(1, rel=1e-6, abs=1e-12) | |
| True | |
| **Non-numeric types** | |
| You can also use ``approx`` to compare non-numeric types, or dicts and | |
| sequences containing non-numeric types, in which case it falls back to | |
| strict equality. This can be useful for comparing dicts and sequences that | |
| can contain optional values:: | |
| >>> {"required": 1.0000005, "optional": None} == approx({"required": 1, "optional": None}) | |
| True | |
| >>> [None, 1.0000005] == approx([None,1]) | |
| True | |
| >>> ["foo", 1.0000005] == approx([None,1]) | |
| False | |
| **datetime and timedelta** | |
| You can also use ``approx`` to compare :class:`~datetime.datetime` and | |
| :class:`~datetime.timedelta` objects by specifying an absolute tolerance | |
| as a :class:`~datetime.timedelta`:: | |
| >>> from datetime import datetime, timedelta | |
| >>> dt1 = datetime(2024, 1, 1, 12, 0, 0) | |
| >>> dt2 = datetime(2024, 1, 1, 12, 0, 0, 500000) | |
| >>> dt1 == approx(dt2, abs=timedelta(seconds=1)) | |
| True | |
| Note that ``rel`` is not supported for datetime comparisons. | |
| For timedelta comparisons, ``rel`` is a number (not a timedelta) that | |
| represents a relative tolerance -- a fraction of the expected value. | |
| ``abs`` must be a ``timedelta`` object in both cases. | |
| .. versionadded:: 8.4 | |
| If you're thinking about using ``approx``, then you might want to know how | |
| it compares to other good ways of comparing floating-point numbers. All of | |
| these algorithms are based on relative and absolute tolerances and should | |
| agree for the most part, but they do have meaningful differences: | |
| - ``math.isclose(a, b, rel_tol=1e-9, abs_tol=0.0)``: True if the relative | |
| tolerance is met w.r.t. either ``a`` or ``b`` or if the absolute | |
| tolerance is met. Because the relative tolerance is calculated w.r.t. | |
| both ``a`` and ``b``, this test is symmetric (i.e. neither ``a`` nor | |
| ``b`` is a "reference value"). You have to specify an absolute tolerance | |
| if you want to compare to ``0.0`` because there is no tolerance by | |
| default. More information: :py:func:`math.isclose`. | |
| - ``numpy.isclose(a, b, rtol=1e-5, atol=1e-8)``: True if the difference | |
| between ``a`` and ``b`` is less that the sum of the relative tolerance | |
| w.r.t. ``b`` and the absolute tolerance. Because the relative tolerance | |
| is only calculated w.r.t. ``b``, this test is asymmetric and you can | |
| think of ``b`` as the reference value. Support for comparing sequences | |
| is provided by :py:func:`numpy.allclose`. More information: | |
| :std:doc:`numpy:reference/generated/numpy.isclose`. | |
| - ``unittest.TestCase.assertAlmostEqual(a, b)``: True if ``a`` and ``b`` | |
| are within an absolute tolerance of ``1e-7``. No relative tolerance is | |
| considered , so this function is not appropriate for very large or very | |
| small numbers. Also, it's only available in subclasses of ``unittest.TestCase`` | |
| and it's ugly because it doesn't follow PEP8. More information: | |
| :py:meth:`unittest.TestCase.assertAlmostEqual`. | |
| - ``a == pytest.approx(b, rel=1e-6, abs=1e-12)``: True if the relative | |
| tolerance is met w.r.t. ``b`` or if the absolute tolerance is met. | |
| Because the relative tolerance is only calculated w.r.t. ``b``, this test | |
| is asymmetric and you can think of ``b`` as the reference value. In the | |
| special case that you explicitly specify an absolute tolerance but not a | |
| relative tolerance, only the absolute tolerance is considered. | |
| .. note:: | |
| ``approx`` can handle numpy arrays, but we recommend the | |
| specialised test helpers in :std:doc:`numpy:reference/routines.testing` | |
| if you need support for comparisons, NaNs, or ULP-based tolerances. | |
| To match strings using regex, you can use | |
| `Matches <https://github.com/asottile/re-assert#re_assertmatchespattern-str-args-kwargs>`_ | |
| from the | |
| `re_assert package <https://github.com/asottile/re-assert>`_. | |
| .. note:: | |
| Unlike built-in equality, this function considers | |
| booleans unequal to numeric zero or one. For example:: | |
| >>> 1 == approx(True) | |
| False | |
| .. warning:: | |
| .. versionchanged:: 3.2 | |
| In order to avoid inconsistent behavior, :py:exc:`TypeError` is | |
| raised for ``>``, ``>=``, ``<`` and ``<=`` comparisons. | |
| The example below illustrates the problem:: | |
| assert approx(0.1) > 0.1 + 1e-10 # calls approx(0.1).__gt__(0.1 + 1e-10) | |
| assert 0.1 + 1e-10 > approx(0.1) # calls approx(0.1).__lt__(0.1 + 1e-10) | |
| In the second example one expects ``approx(0.1).__le__(0.1 + 1e-10)`` | |
| to be called. But instead, ``approx(0.1).__lt__(0.1 + 1e-10)`` is used to | |
| comparison. This is because the call hierarchy of rich comparisons | |
| follows a fixed behavior. More information: :py:meth:`object.__ge__` | |
| .. versionchanged:: 3.7.1 | |
| ``approx`` raises ``TypeError`` when it encounters a dict value or | |
| sequence element of non-numeric type. | |
| .. versionchanged:: 6.1.0 | |
| ``approx`` falls back to strict equality for non-numeric types instead | |
| of raising ``TypeError``. | |
| """ | |
| # Delegate the comparison to a class that knows how to deal with the type | |
| # of the expected value (e.g. int, float, list, dict, numpy.array, etc). | |
| # | |
| # The primary responsibility of these classes is to implement ``__eq__()`` | |
| # and ``__repr__()``. The former is used to actually check if some | |
| # "actual" value is equivalent to the given expected value within the | |
| # allowed tolerance. The latter is used to show the user the expected | |
| # value and tolerance, in the case that a test failed. | |
| # | |
| # The actual logic for making approximate comparisons can be found in | |
| # ApproxScalar, which is used to compare individual numbers. All of the | |
| # other Approx classes eventually delegate to this class. The ApproxBase | |
| # class provides some convenient methods and overloads, but isn't really | |
| # essential. | |
| __tracebackhide__ = True | |
| if isinstance(expected, Decimal): | |
| cls: type[ApproxBase] = ApproxDecimal | |
| elif isinstance(expected, Mapping): | |
| cls = ApproxMapping | |
| elif (np_array := _as_numpy_array(expected)) is not None: | |
| expected = np_array | |
| cls = ApproxNumpy | |
| elif _is_sequence_like(expected): | |
| cls = ApproxSequenceLike | |
| elif isinstance(expected, Collection) and not isinstance(expected, str | bytes): | |
| msg = f"pytest.approx() only supports ordered sequences, but got: {expected!r}" | |
| raise TypeError(msg) | |
| elif isinstance(expected, (datetime, timedelta)): | |
| cls = ApproxTimedelta | |
| else: | |
| cls = ApproxScalar | |
| return cls(expected, rel, abs, nan_ok) | |
| def _is_sequence_like(expected: object) -> bool: | |
| return ( | |
| hasattr(expected, "__getitem__") | |
| and isinstance(expected, Sized) | |
| and not isinstance(expected, str | bytes) | |
| ) | |
| def _as_numpy_array(obj: object) -> ndarray | None: | |
| """ | |
| Return an ndarray if the given object is implicitly convertible to ndarray, | |
| and numpy is already imported, otherwise None. | |
| """ | |
| np: Any = sys.modules.get("numpy") | |
| if np is not None: | |
| # avoid infinite recursion on numpy scalars, which have __array__ | |
| if np.isscalar(obj): | |
| return None | |
| elif isinstance(obj, np.ndarray): | |
| return obj | |
| elif hasattr(obj, "__array__") or hasattr(obj, "__array_interface__"): | |
| return np.asarray(obj) | |
| return None | |