From 6be57a3711465c70b3cb4e5ddf5ee373608f6fbf Mon Sep 17 00:00:00 2001 From: Ronny Pfannschmidt Date: Sun, 11 Jun 2017 12:27:16 +0200 Subject: [PATCH] move python api helpers out of the python module this separates exposed normal api from collection elements --- _pytest/python.py | 174 ----------------- _pytest/python_api.py | 430 ++++++++++++++++++++++++++++++++++++++++++ pytest.py | 3 +- 3 files changed, 431 insertions(+), 176 deletions(-) create mode 100644 _pytest/python_api.py diff --git a/_pytest/python.py b/_pytest/python.py index 72269f0f0..1a313a59e 100644 --- a/_pytest/python.py +++ b/_pytest/python.py @@ -6,7 +6,6 @@ import inspect import sys import os import collections -import math from itertools import count import py @@ -1091,179 +1090,6 @@ def _showfixtures_main(config, session): red=True) -# builtin pytest.raises helper - -def raises(expected_exception, *args, **kwargs): - """ - Assert that a code block/function call raises ``expected_exception`` - and raise a failure exception otherwise. - - This helper produces a ``ExceptionInfo()`` object (see below). - - If using Python 2.5 or above, you may use this function as a - context manager:: - - >>> with raises(ZeroDivisionError): - ... 1/0 - - .. versionchanged:: 2.10 - - In the context manager form you may use the keyword argument - ``message`` to specify a custom failure message:: - - >>> with raises(ZeroDivisionError, message="Expecting ZeroDivisionError"): - ... pass - Traceback (most recent call last): - ... - Failed: Expecting ZeroDivisionError - - - .. note:: - - When using ``pytest.raises`` as a context manager, it's worthwhile to - note that normal context manager rules apply and that the exception - raised *must* be the final line in the scope of the context manager. - Lines of code after that, within the scope of the context manager will - not be executed. For example:: - - >>> value = 15 - >>> with raises(ValueError) as exc_info: - ... if value > 10: - ... raise ValueError("value must be <= 10") - ... assert exc_info.type == ValueError # this will not execute - - Instead, the following approach must be taken (note the difference in - scope):: - - >>> with raises(ValueError) as exc_info: - ... if value > 10: - ... raise ValueError("value must be <= 10") - ... - >>> assert exc_info.type == ValueError - - Or you can use the keyword argument ``match`` to assert that the - exception matches a text or regex:: - - >>> with raises(ValueError, match='must be 0 or None'): - ... raise ValueError("value must be 0 or None") - - >>> with raises(ValueError, match=r'must be \d+$'): - ... raise ValueError("value must be 42") - - - Or you can specify a callable by passing a to-be-called lambda:: - - >>> raises(ZeroDivisionError, lambda: 1/0) - - - or you can specify an arbitrary callable with arguments:: - - >>> def f(x): return 1/x - ... - >>> raises(ZeroDivisionError, f, 0) - - >>> raises(ZeroDivisionError, f, x=0) - - - A third possibility is to use a string to be executed:: - - >>> raises(ZeroDivisionError, "f(0)") - - - .. autoclass:: _pytest._code.ExceptionInfo - :members: - - .. note:: - Similar to caught exception objects in Python, explicitly clearing - local references to returned ``ExceptionInfo`` objects can - help the Python interpreter speed up its garbage collection. - - Clearing those references breaks a reference cycle - (``ExceptionInfo`` --> caught exception --> frame stack raising - the exception --> current frame stack --> local variables --> - ``ExceptionInfo``) which makes Python keep all objects referenced - from that cycle (including all local variables in the current - frame) alive until the next cyclic garbage collection run. See the - official Python ``try`` statement documentation for more detailed - information. - - """ - __tracebackhide__ = True - msg = ("exceptions must be old-style classes or" - " derived from BaseException, not %s") - if isinstance(expected_exception, tuple): - for exc in expected_exception: - if not isclass(exc): - raise TypeError(msg % type(exc)) - elif not isclass(expected_exception): - raise TypeError(msg % type(expected_exception)) - - message = "DID NOT RAISE {0}".format(expected_exception) - match_expr = None - - if not args: - if "message" in kwargs: - message = kwargs.pop("message") - if "match" in kwargs: - match_expr = kwargs.pop("match") - message += " matching '{0}'".format(match_expr) - return RaisesContext(expected_exception, message, match_expr) - elif isinstance(args[0], str): - code, = args - assert isinstance(code, str) - frame = sys._getframe(1) - loc = frame.f_locals.copy() - loc.update(kwargs) - #print "raises frame scope: %r" % frame.f_locals - try: - code = _pytest._code.Source(code).compile() - py.builtin.exec_(code, frame.f_globals, loc) - # XXX didn'T mean f_globals == f_locals something special? - # this is destroyed here ... - except expected_exception: - return _pytest._code.ExceptionInfo() - else: - func = args[0] - try: - func(*args[1:], **kwargs) - except expected_exception: - return _pytest._code.ExceptionInfo() - fail(message) - - -raises.Exception = fail.Exception - - -class RaisesContext(object): - def __init__(self, expected_exception, message, match_expr): - self.expected_exception = expected_exception - self.message = message - self.match_expr = match_expr - self.excinfo = None - - def __enter__(self): - self.excinfo = object.__new__(_pytest._code.ExceptionInfo) - return self.excinfo - - def __exit__(self, *tp): - __tracebackhide__ = True - if tp[0] is None: - fail(self.message) - if sys.version_info < (2, 7): - # py26: on __exit__() exc_value often does not contain the - # exception value. - # http://bugs.python.org/issue7853 - if not isinstance(tp[1], BaseException): - exc_type, value, traceback = tp - tp = exc_type, exc_type(value), traceback - self.excinfo.__init__(tp) - suppress_exception = issubclass(self.excinfo.type, self.expected_exception) - if sys.version_info[0] == 2 and suppress_exception: - sys.exc_clear() - if self.match_expr: - self.excinfo.match(self.match_expr) - return suppress_exception - # # the basic pytest Function item diff --git a/_pytest/python_api.py b/_pytest/python_api.py new file mode 100644 index 000000000..1b27ba327 --- /dev/null +++ b/_pytest/python_api.py @@ -0,0 +1,430 @@ +import math +import sys + +import py + +from _pytest.compat import isclass +from _pytest.runner import fail +import _pytest._code +# builtin pytest.approx helper + + +class approx(object): + """ + Assert that two numbers (or two sets of numbers) are equal to each other + within some tolerance. + + Due to the `intricacies of floating-point arithmetic`__, numbers that we + would intuitively expect to be equal are not always so:: + + >>> 0.1 + 0.2 == 0.3 + False + + __ https://docs.python.org/3/tutorial/floatingpoint.html + + 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 on sequences of numbers:: + + >>> (0.1 + 0.2, 0.2 + 0.4) == approx((0.3, 0.6)) + True + + 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. Infinite numbers are another special case. They are only + considered equal to themselves, regardless of the relative tolerance. 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 + + 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. Only available in python>=3.5. `More information...`__ + + __ https://docs.python.org/3/library/math.html#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 ``numpy.allclose``. `More information...`__ + + __ http://docs.scipy.org/doc/numpy-1.10.0/reference/generated/numpy.isclose.html + + - ``unittest.TestCase.assertAlmostEqual(a, b)``: True if ``a`` and ``b`` + are within an absolute tolerance of ``1e-7``. No relative tolerance is + considered and the absolute tolerance cannot be changed, 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...`__ + + __ https://docs.python.org/3/library/unittest.html#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. + """ + + def __init__(self, expected, rel=None, abs=None): + self.expected = expected + self.abs = abs + self.rel = rel + + def __repr__(self): + return ', '.join(repr(x) for x in self.expected) + + def __eq__(self, actual): + from collections import Iterable + if not isinstance(actual, Iterable): + actual = [actual] + if len(actual) != len(self.expected): + return False + return all(a == x for a, x in zip(actual, self.expected)) + + __hash__ = None + + def __ne__(self, actual): + return not (actual == self) + + @property + def expected(self): + # Regardless of whether the user-specified expected value is a number + # or a sequence of numbers, return a list of ApproxNotIterable objects + # that can be compared against. + from collections import Iterable + approx_non_iter = lambda x: ApproxNonIterable(x, self.rel, self.abs) + if isinstance(self._expected, Iterable): + return [approx_non_iter(x) for x in self._expected] + else: + return [approx_non_iter(self._expected)] + + @expected.setter + def expected(self, expected): + self._expected = expected + + +class ApproxNonIterable(object): + """ + Perform approximate comparisons for single numbers only. + + In other words, the ``expected`` attribute for objects of this class must + be some sort of number. This is in contrast to the ``approx`` class, where + the ``expected`` attribute can either be a number of a sequence of numbers. + This class is responsible for making comparisons, while ``approx`` is + responsible for abstracting the difference between numbers and sequences of + numbers. Although this class can stand on its own, it's only meant to be + used within ``approx``. + """ + + def __init__(self, expected, rel=None, abs=None): + self.expected = expected + self.abs = abs + self.rel = rel + + def __repr__(self): + if isinstance(self.expected, complex): + return str(self.expected) + + # Infinities aren't compared using tolerances, so don't show a + # tolerance. + if math.isinf(self.expected): + return str(self.expected) + + # If a sensible tolerance can't be calculated, self.tolerance will + # raise a ValueError. In this case, display '???'. + try: + vetted_tolerance = '{:.1e}'.format(self.tolerance) + except ValueError: + vetted_tolerance = '???' + + if sys.version_info[0] == 2: + return '{0} +- {1}'.format(self.expected, vetted_tolerance) + else: + return u'{0} \u00b1 {1}'.format(self.expected, vetted_tolerance) + + def __eq__(self, actual): + # Short-circuit exact equality. + if actual == self.expected: + return True + + # 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. + return abs(self.expected - actual) <= self.tolerance + + __hash__ = None + + def __ne__(self, actual): + return not (actual == self) + + @property + def tolerance(self): + set_default = lambda x, default: 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, 1e-12) + + if absolute_tolerance < 0: + raise ValueError("absolute tolerance can't be negative: {}".format(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, 1e-6) * abs(self.expected) + + if relative_tolerance < 0: + raise ValueError("relative tolerance can't be negative: {}".format(absolute_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) + +# builtin pytest.raises helper + +def raises(expected_exception, *args, **kwargs): + """ + Assert that a code block/function call raises ``expected_exception`` + and raise a failure exception otherwise. + + This helper produces a ``ExceptionInfo()`` object (see below). + + If using Python 2.5 or above, you may use this function as a + context manager:: + + >>> with raises(ZeroDivisionError): + ... 1/0 + + .. versionchanged:: 2.10 + + In the context manager form you may use the keyword argument + ``message`` to specify a custom failure message:: + + >>> with raises(ZeroDivisionError, message="Expecting ZeroDivisionError"): + ... pass + Traceback (most recent call last): + ... + Failed: Expecting ZeroDivisionError + + + .. note:: + + When using ``pytest.raises`` as a context manager, it's worthwhile to + note that normal context manager rules apply and that the exception + raised *must* be the final line in the scope of the context manager. + Lines of code after that, within the scope of the context manager will + not be executed. For example:: + + >>> value = 15 + >>> with raises(ValueError) as exc_info: + ... if value > 10: + ... raise ValueError("value must be <= 10") + ... assert exc_info.type == ValueError # this will not execute + + Instead, the following approach must be taken (note the difference in + scope):: + + >>> with raises(ValueError) as exc_info: + ... if value > 10: + ... raise ValueError("value must be <= 10") + ... + >>> assert exc_info.type == ValueError + + Or you can use the keyword argument ``match`` to assert that the + exception matches a text or regex:: + + >>> with raises(ValueError, match='must be 0 or None'): + ... raise ValueError("value must be 0 or None") + + >>> with raises(ValueError, match=r'must be \d+$'): + ... raise ValueError("value must be 42") + + + Or you can specify a callable by passing a to-be-called lambda:: + + >>> raises(ZeroDivisionError, lambda: 1/0) + + + or you can specify an arbitrary callable with arguments:: + + >>> def f(x): return 1/x + ... + >>> raises(ZeroDivisionError, f, 0) + + >>> raises(ZeroDivisionError, f, x=0) + + + A third possibility is to use a string to be executed:: + + >>> raises(ZeroDivisionError, "f(0)") + + + .. autoclass:: _pytest._code.ExceptionInfo + :members: + + .. note:: + Similar to caught exception objects in Python, explicitly clearing + local references to returned ``ExceptionInfo`` objects can + help the Python interpreter speed up its garbage collection. + + Clearing those references breaks a reference cycle + (``ExceptionInfo`` --> caught exception --> frame stack raising + the exception --> current frame stack --> local variables --> + ``ExceptionInfo``) which makes Python keep all objects referenced + from that cycle (including all local variables in the current + frame) alive until the next cyclic garbage collection run. See the + official Python ``try`` statement documentation for more detailed + information. + + """ + __tracebackhide__ = True + msg = ("exceptions must be old-style classes or" + " derived from BaseException, not %s") + if isinstance(expected_exception, tuple): + for exc in expected_exception: + if not isclass(exc): + raise TypeError(msg % type(exc)) + elif not isclass(expected_exception): + raise TypeError(msg % type(expected_exception)) + + message = "DID NOT RAISE {0}".format(expected_exception) + match_expr = None + + if not args: + if "message" in kwargs: + message = kwargs.pop("message") + if "match" in kwargs: + match_expr = kwargs.pop("match") + message += " matching '{0}'".format(match_expr) + return RaisesContext(expected_exception, message, match_expr) + elif isinstance(args[0], str): + code, = args + assert isinstance(code, str) + frame = sys._getframe(1) + loc = frame.f_locals.copy() + loc.update(kwargs) + #print "raises frame scope: %r" % frame.f_locals + try: + code = _pytest._code.Source(code).compile() + py.builtin.exec_(code, frame.f_globals, loc) + # XXX didn'T mean f_globals == f_locals something special? + # this is destroyed here ... + except expected_exception: + return _pytest._code.ExceptionInfo() + else: + func = args[0] + try: + func(*args[1:], **kwargs) + except expected_exception: + return _pytest._code.ExceptionInfo() + fail(message) + + +raises.Exception = fail.Exception + + +class RaisesContext(object): + def __init__(self, expected_exception, message, match_expr): + self.expected_exception = expected_exception + self.message = message + self.match_expr = match_expr + self.excinfo = None + + def __enter__(self): + self.excinfo = object.__new__(_pytest._code.ExceptionInfo) + return self.excinfo + + def __exit__(self, *tp): + __tracebackhide__ = True + if tp[0] is None: + fail(self.message) + if sys.version_info < (2, 7): + # py26: on __exit__() exc_value often does not contain the + # exception value. + # http://bugs.python.org/issue7853 + if not isinstance(tp[1], BaseException): + exc_type, value, traceback = tp + tp = exc_type, exc_type(value), traceback + self.excinfo.__init__(tp) + suppress_exception = issubclass(self.excinfo.type, self.expected_exception) + if sys.version_info[0] == 2 and suppress_exception: + sys.exc_clear() + if self.match_expr: + self.excinfo.match(self.match_expr) + return suppress_exception diff --git a/pytest.py b/pytest.py index e3c72023c..da6b64910 100644 --- a/pytest.py +++ b/pytest.py @@ -22,11 +22,10 @@ from _pytest.skipping import xfail from _pytest.main import Item, Collector, File, Session from _pytest.fixtures import fillfixtures as _fillfuncargs from _pytest.python import ( - raises, Module, Class, Instance, Function, Generator, ) -from _pytest.python_api import approx +from _pytest.python_api import approx, raises set_trace = __pytestPDB.set_trace