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Test assertions about changes in monitored values.

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Octocat-spinner-32 .gitignore
Octocat-spinner-32 README.md
Octocat-spinner-32 UNLICENSE
Octocat-spinner-32 assert_changes.py
Octocat-spinner-32 setup.py
Octocat-spinner-32 test.py
README.md

assert_changes

Track simple changes in values from the start to end of a context, and raise an AssertionError if the final value was not as expected.

Simply pass assert_changes() two functions: one which returns a snapshot of the monitored value, and another which represents the expected change.

You can also pass in a function which compares the old and new versions, returning True if the change is acceptable and False otherwise. This allows you to use operators other than simple equality for your tests.

Installation

pip install assert_changes

Usage

Using the new parameter:

>>> value = 123
>>> with assert_changes(lambda: value, new=lambda x: x + 1):
...     value = 124

>>> value = 123
>>> with assert_changes(lambda: value, new=lambda x: x + 1):
...     value = 122
Traceback (most recent call last):
...
AssertionError: Value changed from 123 to 123 (expected: 124)

Using the cmp parameter:

>>> import operator
>>> value = 123
>>> with assert_changes(lambda: value, cmp=operator.lt):
...     value += 4

>>> value = 123
>>> with assert_changes(lambda: value, cmp=operator.gt):
...     value += 4
Traceback (most recent call last):
...
AssertionError: operator.gt(123, 127) not True

You can even use an assertion as your comparison function:

>>> value = 123
>>> with assert_changes(lambda: value, cmp=assert_greater_than):
...     value += 4
Traceback (most recent call last):
...
AssertionError: 123 not greater than 127

(Un)license

This is free and unencumbered software released into the public domain.

Anyone is free to copy, modify, publish, use, compile, sell, or distribute this software, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.

In jurisdictions that recognize copyright laws, the author or authors of this software dedicate any and all copyright interest in the software to the public domain. We make this dedication for the benefit of the public at large and to the detriment of our heirs and successors. We intend this dedication to be an overt act of relinquishment in perpetuity of all present and future rights to this software under copyright law.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

For more information, please refer to http://unlicense.org/

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