pytest-check

A pytest plugin that allows multiple failures per test.

Normally, a test funcion will fail and stop running with the first failed assert.
That's totally fine for tons of kinds of software tests.
However, there are times where you'd like to check more than one thing, and you'd really like to know the results of each check, even if one of them fails.

pytest-check allows multiple failed "checks" per test function, so you can see the whole picture of what's going wrong.

Installation

From PyPI:

$ pip install pytest-check

Example

Quick example of where you might want multiple checks:

import httpx
from pytest_check import check

def test_httpx_get():
    r = httpx.get('https://www.example.org/')
    # bail if bad status code
    assert r.status_code == 200
    # but if we get to here
    # then check everything else without stopping
    with check: 
        assert r.is_redirect == False
    with check: 
        assert r.encoding == 'utf-8'
    with check: 
        assert 'Example Domain' in r.text

Import vs fixture

The example above used import: from pytest_check import check.

You can also grab check as a fixture with no import:

def test_httpx_get(check):
    r = httpx.get('https://www.example.org/')
    ...
    with check: 
        assert r.is_redirect == False
    ...

Validation functions

check also helper functions for common checks:

• check.equal - a == b
• check.not_equal - a != b
• check.is_ - a is b
• check.is_not - a is not b
• check.is_true - bool(x) is True
• check.is_false - bool(x) is False
• check.is_none - x is None
• check.is_not_none - x is not None
• check.is_in - a in b
• check.is_not_in - a not in b
• check.is_instance - isinstance(a, b)
• check.is_not_instance - not isinstance(a, b)
• check.almost_equal - a == pytest.approx(b, rel, abs) see at: pytest.approx
• check.not_almost_equal - a != pytest.approx(b, rel, abs) see at: pytest.approx
• check.greater - a > b
• check.greater_equal - a >= b
• check.less - a < b
• check.less_equal - a <= b
• check.raises - func raises given exception similar to pytest.raises

Using raises as a context manager

raises can also be used as a context manager:

from pytest_check import raises


def test_context_manager():
    with raises(AssertionError):
        x = 3
        assert 1 < x < 4

Just like with check as a context manager, execution won't proceed past the first line that throws an error, even if it is successfully captured and logged by pytest-check. Break your assertions over multiple uses of raises if you encounter this problem.

Defining your own check functions

The @check.check_func decorator allows you to wrap any test helper that has an assert statement in it to be a non-blocking assert function.

from pytest_check import check

@check.check_func
def is_four(a):
    assert a == 4

def test_all_four():
    is_four(1)
    is_four(2)
    is_four(3)
    is_four(4)

Pseudo-tracebacks

With check, tests can have multiple failures per test. This would possibly make for extensive output if we include the full traceback for every failure. To make the output a little more concise, pytest-check implements a shorter version, which we call pseudo-tracebacks.

For example, take this test:

def test_example():
    a = 1
    b = 2
    c = [2, 4, 6]
    check.greater(a, b)
    check.less_equal(b, a)
    check.is_in(a, c, "Is 1 in the list")
    check.is_not_in(b, c, "make sure 2 isn't in list")

This will result in:

=================================== FAILURES ===================================
_________________________________ test_example _________________________________
FAILURE:
assert 1 > 2
  test_check.py, line 14, in test_example() -> check.greater(a, b)
FAILURE:
assert 2 <= 1
  test_check.py, line 15, in test_example() -> check.less_equal(b, a)
FAILURE: Is 1 in the list
assert 1 in [2, 4, 6]
  test_check.py, line 16, in test_example() -> check.is_in(a, c, "Is 1 in the list")
FAILURE: make sure 2 isn't in list
assert 2 not in [2, 4, 6]
  test_check.py, line 17, in test_example() -> check.is_not_in(b, c, "make sure 2 isn't in list")
------------------------------------------------------------
Failed Checks: 4
=========================== 1 failed in 0.11 seconds ===========================

Red output

The failures will also be red, unless you turn that off with pytests --color=no.

No output

You can turn off the failure reports with pytests --tb=no.

Stop on Fail (maxfail behavior)

Setting -x or --maxfail=1 will cause this plugin to abort testing after the first failed check.

Setting -maxfail=2 or greater will turn off any handling of maxfail within this plugin and the behavior is controlled by pytest.

In other words, the maxfail count is counting tests, not checks. The exception is the case of 1, where we want to stop on the very first failed check.

Contributing

Contributions are very welcome. Tests can be run with tox. Test coverage is now 100%. Please make sure to keep it at 100%. If you have an awesome pull request and need help with getting coverage back up, let me know.

License

Distributed under the terms of the MIT license, "pytest-check" is free and open source software

Issues

If you encounter any problems, please file an issue along with a detailed description.

Changelog

See changelog.md