================================= Flake8 Unittest Assertion Checker

|PyPI Version| |Python Versions|

flake8-assertive is a Flake8 <https://flake8.pycqa.org/>_ extension that encourages using richer, more specific unittest_ assertions beyond just the typical assertEqual(a, b) and assertTrue(x) methods. The suggested methods perform more precise checks and provide better failure messages than the generic methods.

+------------------------------------------+-----------------------------------+------+ | Original | Suggestion | Code | +==========================================+===================================+======+ | assertTrue(a == b) | assertEqual(a, b) | A500 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a != b) | assertNotEqual(a, b) | A500 | +------------------------------------------+-----------------------------------+------+ | assertFalse(a == b) | assertNotEqual(a, b) | A500 | +------------------------------------------+-----------------------------------+------+ | assertFalse(a != b) | assertEqual(a, b) | A500 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a < b) | assertLess(a, b) | A500 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a <= b) | assertLessEqual(a, b) | A500 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a > b) | assertGreater(a, b) | A500 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a >= b) | assertGreaterEqual(a, b) | A500 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a is b) | assertIs(a, b) | A501 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a is not b) | assertIsNot(a, b) | A501 | +------------------------------------------+-----------------------------------+------+ | assertFalse(a is b) | assertNotIs(a, b) | A501 | +------------------------------------------+-----------------------------------+------+ | assertFalse(a is not b) | assertIs(a, b) | A501 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a in b) | assertIn(a, b) | A501 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a not in b) | assertNotIn(a, b) | A501 | +------------------------------------------+-----------------------------------+------+ | assertFalse(a in b) | assertNotIn(a, b) | A501 | +------------------------------------------+-----------------------------------+------+ | assertTrue(isinstance(a, b)) | assertIsInstance(a, b) | A501 | +------------------------------------------+-----------------------------------+------+ | assertFalse(isinstance(a, b)) | assertNotIsInstance(a, b) | A501 | +------------------------------------------+-----------------------------------+------+ | assertEqual(a, round(b, x)) | assertAlmostEqual(a, b, x) | A501 | +------------------------------------------+-----------------------------------+------+ | assertAlmostEqual(a, round(b, x)) | assertAlmostEqual(a, b, x) | A501 | +------------------------------------------+-----------------------------------+------+ | assertNotEqual(a, round(b, x)) | assertNotAlmostEqual(a, b, x) | A501 | +------------------------------------------+-----------------------------------+------+ | assertNotAlmostEqual(a, round(b, x)) | assertNotAlmostEqual(a, b, x) | A501 | +------------------------------------------+-----------------------------------+------+ | assertEqual(a, None) | assertIsNone(a) | A502 | +------------------------------------------+-----------------------------------+------+ | assertNotEqual(a, None) | assertIsNotNone(a) | A502 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a is None) | assertIsNone(a) | A502 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a is not None) | assertIsNotNone(a) | A502 | +------------------------------------------+-----------------------------------+------+ | assertFalse(a is None) | assertIsNotNone(a) | A502 | +------------------------------------------+-----------------------------------+------+ | assertFalse(a is not None) | assertIsNone(a) | A502 | +------------------------------------------+-----------------------------------+------+ | assertEqual(a, True) | assertTrue(a) | A502 | +------------------------------------------+-----------------------------------+------+ | assertEqual(a, False) | assertFalse(a) | A502 | +------------------------------------------+-----------------------------------+------+ | assertEquals(a, b) | assertEqual(a, b) | A503 | +------------------------------------------+-----------------------------------+------+ | assertNotEquals(a, b) | assertNotEqual(a, b) | A503 | +------------------------------------------+-----------------------------------+------+ | assertAlmostEquals(a, b, x) | assertAlmostEqual(a, b, x) | A503 | +------------------------------------------+-----------------------------------+------+ | assertNotAlmostEquals(a, b, x) | assertNotAlmostEqual(a, b, x) | A503 | +------------------------------------------+-----------------------------------+------+ | assertTrue(a, b) | assertTrue(a, msg=b) | A504 | +------------------------------------------+-----------------------------------+------+ | assertFalse(a, b) | assertFalse(a, msg=b) | A504 | +------------------------------------------+-----------------------------------+------+

Note that some suggestions are normalized forms of the original, such as when a double-negative is used (assertFalse(a != b) → assertEqual(a, b)). There aren't suggestions for things like assertFalse(a > b), which may or may not be equivalent to assertLessEqual(a, b).

Installation

Install from PyPI using pip:

.. code-block:: sh

$ pip install flake8-assertive

The extension will be activated automatically by flake8. You can verify that it has been loaded by inspecting the flake8 --version string.

.. code-block:: sh

$ flake8 --version
4.0.1 (assertive: 2.1.0, ...) CPython 3.9.10 on Darwin

Error Codes

This extension adds three new error codes__ (using the A50 prefix):

• A500: prefer {func} for '{op}' comparisons
• A501: prefer {func} for '{op}' expressions
• A502: prefer {func} instead of comparing to {obj}
• A503: use {func} instead of the deprecated {name}
• A504: prefer the 'msg=' kwarg for {func} diagnostics

.. __: https://flake8.pycqa.org/en/latest/user/error-codes.html

Configuration

Configuration values are specified in the [flake8] section of your config file_ or as command line arguments (e.g. --assertive-snakecase).

• assertive-snakecase: suggest snake_case assert method names (e.g. assert_true()) instead of the standard names (e.g. assertTrue())
• assertive-test-pattern: fnmatch_ pattern for identifying unittest test files (and all other files will be skipped)

.. _fnmatch: https://docs.python.org/library/fnmatch.html .. _unittest: https://docs.python.org/library/unittest.html .. _config file: https://flake8.pycqa.org/en/latest/user/configuration.html

Caveats

There are some specific cases when the suggestion might not match the intent of the original.

Testing the equality operator

``assertEqual()`` won't use the ``==`` operator if the comparison has been
delegated to a `type-specific equalilty function`__. By default, this is the
case for strings, sequences, lists, tuples, sets, and dicts.

.. __: https://docs.python.org/3/library/unittest.html#unittest.TestCase.addTypeEqualityFunc

If your intent is to specifically test the ``==`` operator, consider writing
the assertion like this instead:

.. code-block:: python

    assertIs(a == b, True)

This approach has the benefit of verifying that the type's ``__eq__``
implementation returns a boolean value. Unfortunately, it also has the
downside of reporting the result of ``a == b`` on failure instead of the
values of ``a`` and ``b``.

Suggested by: `Serhiy Storchaka <https://twitter.com/SerhiyStorchaka>`_

.. |PyPI Version| image:: https://img.shields.io/pypi/v/flake8-assertive.svg
   :target: https://pypi.python.org/pypi/flake8-assertive
.. |Python Versions| image:: https://img.shields.io/pypi/pyversions/flake8-assertive.svg
   :target: https://pypi.python.org/pypi/flake8-assertive

Copyright (c) 2018-present Jon Parise

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

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 OR COPYRIGHT HOLDERS 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.

Changes
=======

2.1.0 (2022-03-15)
------------------

* Suggest using an explicit `msg` keyword argument with ``assertTrue()`` and
  ``assertFalse()`` to avoid accidental two-argument misuse. This is controlled
  by a new error code: ``A504``

2.0.0 (2021-12-30)
------------------

* Drop support for Python 2.7 and 3.6, and add 3.10.
* Drop support for flake8 2.x versions.

1.3.0 (2020-10-12)
------------------

* Drop Python version 3.5 support and add version 3.9.

1.2.1 (2019-12-08)
------------------

* Support keyword arguments in assert method calls.

1.2.0 (2019-12-05)
------------------

* Suggest the preferred names for deprecated methods, such as
  ``assertEqual()`` instead of ``assertEquals()``.

1.1.0 (2019-06-26)
------------------

* Suggest ``assertAlmostEqual(a, b, x)`` for ``round()`` expressions like in
  ``assertEqual(a, round(b, x))`` and ``assertAlmostEqual(a, round(b, x))``
  (and similar for ``assertNotEqual()`` and ``assertNotAlmostEqual()``.
* Recognize ``assertAmostEquals()`` and ``assertNotAlmostEquals()`` as aliases
  for ``assertAlmostEqual()`` and ``assertNotAlmostEqual()``.
* Drop Python 3.4 as a supported version since it has been officially retired.

1.0.1 (2018-07-03)
------------------

* Don't make suggestions for assertions containing multiple comparison
  operations (e.g. ``assertTrue(a == b == c)``).

1.0.0 (2018-06-04)
------------------

* Suggest ``assertIsNone(a)`` for ``assertTrue(a is None)``, etc.
* Recognize ``assertEquals()`` and ``assertNotEquals()`` as aliases for
  ``assertEqual()`` and ``assertNotEqual()``.

0.9.0 (2018-05-14)
------------------

* Initial beta release