/usr/lib/python2.7/dist-packages/preggy/core.py is in python-preggy 1.1.3-1.
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'''preggy core: the `Expect` class, and the `@assertion` and `@create_assertions` decorators.
'''
# preggy assertions
# https://github.com/heynemann/preggy
# Licensed under the MIT license:
# http://www.opensource.org/licenses/mit-license
# Copyright (c) 2013 Bernardo Heynemann heynemann@gmail.com
from __future__ import absolute_import
import functools
from contextlib import contextmanager
from preggy import utils
_registered_assertions = utils.AssertionsMap()
def assertion(func):
'''Function decorator. Provides lower-level control for custom
assertions than `@preggy.create_assertions`.
This decorator is preferable over `@preggy.create_assertions`
if you need to fine-tune your error message, or if your assertion
doesn’t have a corresponding `not_`.
Unlike `@preggy.create_assertions`, functions decorated with
this shouldn’t return a boolean. Instead, they should check for
undesirable conditions and raise an `AssertionError` when appropriate.
Whenever possible, you should declare both the normal assertion as well
as a `not_` counterpart, so they can be used like this:
... # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
>>>
>>> import preggy
>>> from preggy.core import Expect as expect
>>>
>>> @preggy.assertion
... def to_be_a_positive_integer(topic):
... if not topic > 0:
... raise AssertionError("Expected topic('{topic}') to be a positive integer".format(topic=topic))
...
>>> @preggy.assertion
... def not_to_be_a_positive_integer(topic):
... if not topic < 0:
... raise AssertionError("Expected topic('{topic}') not to be a positive integer".format(topic=topic))
...
>>> expect(5).to_be_a_positive_integer()
>>> expect(-3).Not.to_be_a_positive_integer()
'''
if not hasattr(func, 'humanized'):
setattr(func, 'humanized', utils.humanized_name(func.__name__))
@functools.wraps(func)
def wrapper(*args, **kw):
return func(*args, **kw)
_registered_assertions[wrapper.__name__] = wrapper
return wrapper
def create_assertions(func):
'''Function decorator. Use to create custom assertions for your
tests.
''' '''
Creating new assertions for use with `expect` is as simple as using
this decorator on a function. The function expects `topic` as the
first parameter, and `expectation` second:
@preggy.create_assertions
def to_be_greater_than(topic, expected):
return topic > expected
This creates both the assertion AND its `not_*` counterpart.
... # doctest: +ELLIPSIS, +NORMALIZE_WHITESPACE
>>> from preggy.core import (assertion, create_assertions, Expect as expect)
>>> from preggy.assertions import *
>>> expect(2).to_be_greater_than(3)
Traceback (most recent call last):
...
AssertionError: Expected topic(2) to be greater than 3
>>> expect(4).not_to_be_greater_than(3)
Traceback (most recent call last):
...
AssertionError: Expected topic(4) not to be greater than 3
'''
# set custom func attribute "humanized"
setattr(func, 'humanized', utils.humanized_name(func.__name__))
# modified functools.update_wrapper
def _update_wrapper(wrapper, wrapped, not_assertion=True):
'''A modified version of functools.update_wrapper. Auto-modifies the
wrapper's __name__ and __doc__ to create a not_assertion.
'''
# begin as usual
wrapper = functools.update_wrapper(wrapper, wrapped)
# compute overrides for not_* assertions values
if not_assertion:
new_name = 'not_{0.__name__}'.format(wrapped)
new_doc = ''#.format(wrapped)
# set our overrides
setattr(wrapper, '__name__', new_name)
setattr(wrapper, '__doc__', new_doc)
# update to reflect new __name__
setattr(wrapper, 'humanized', utils.humanized_name(wrapper.__name__))
# Return the wrapper so this can be used as a decorator via partial()
return wrapper
# First assertion
@assertion
@functools.wraps(func)
def test_assertion(*args):
raw_msg = utils.format_assertion_msg(func.humanized, *args)
err_msg = raw_msg.format(*args)
if not func(*args):
raise AssertionError(err_msg)
# Second assertion: prepare
def test_not_assertion(*args):
raw_msg = utils.format_assertion_msg('not {0!s}'.format(func.humanized), *args)
err_msg = raw_msg.format(*args)
if func(*args):
raise AssertionError(err_msg)
# Second assertion: update and register
test_not_assertion = _update_wrapper(test_not_assertion, func)
test_not_assertion = assertion(test_not_assertion)
class ErrorToHappenContext(object):
def __init__(self, error_class, message=None):
self.error_class = error_class
self.message = message
self._error = None
@property
def error(self):
return self._error
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
has_exception = exc_type is not None
is_subclass = has_exception and (exc_type is self.error_class or issubclass(exc_type, self.error_class)) or False
if not has_exception:
raise AssertionError('Expected "%s.%s" to happen but no errors happened during execution of with block.' % (
self.error_class.__module__,
self.error_class.__name__,
))
if has_exception and not is_subclass:
raise AssertionError('Expected "%s.%s" to happen but "%s.%s" happened during execution of with block.' % (
self.error_class.__module__,
self.error_class.__name__,
exc_type.__module__,
exc_type.__name__
))
if self.message is not None:
error_msg = getattr(exc_val, 'message', str(exc_val))
if error_msg != self.message:
raise AssertionError('Expected "%s.%s" to have a message of "%s", but the actual error was "%s".' % (
self.error_class.__module__,
self.error_class.__name__,
self.message,
error_msg
))
if has_exception and is_subclass:
self._error = exc_val
return True
return False
class Expect(object):
'''This atypical class provides a key part of the preggy testing syntax.
For example:
>>> from preggy.core import (assertion, create_assertions, Expect as expect)
>>> from preggy.assertions import *
>>>
>>> expect(True).to_be_true()
>>> expect(False).to_be_false()
'''
def __init__(self, topic):
self.topic = topic
if isinstance(self.topic, ErrorToHappenContext):
self.topic = self.topic.error
self.not_assert = False
@classmethod
def not_to_be_here(self):
raise AssertionError("Should not have gotten this far.")
@classmethod
def error_to_happen(self, error_class=Exception, message=None):
return ErrorToHappenContext(error_class, message=message)
def __getattr__(self, name):
# common cases
if name in ['topic', 'not_to_be_here']:
return super(Expect, self).__getattr__(name)
if name == 'Not':
self.not_assert = not self.not_assert
return self
# determine whether assertion is of "not" form
method_name = 'not_{name}'.format(name=name) if self.not_assert else name
# if program gets this far, then it’s time to perform the assertion. (...FINALLY! ;D)
def _assert_topic(*args, **kw):
# Allows chained calls to assertions, such as `expect(topic).to_be_true()`.
return _registered_assertions[method_name](self.topic, *args, **kw)
return _assert_topic
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