pytest-iterassert 0.0.2

Nicer list and iterable assertion messages for pytest

pytest-iterassert

Have you ever wanted to use all or any in a unit test, but found the assert message to be lacking? Do assertions on class attributes in collections almost make you wish you were coding in Java (with a nice assertion framework)?

Then this is the pytest helper for you! pytest-iterassert provides all_match and any_match to give you nice asserts.

The built-in any or all can cause a lot of sadness when tests fail:

    def test_generator_without_iterassert() -> None:
>       assert all(i < 1 for i in range(3))
E       assert False
E        +  where False = all(<genexpr> at 0x10221a250>)

all_match and any_match make debugging easy:

    def test_generator_with_iterassert() -> None:
>       assert all_match(range(3)) < 1
E       assert all(0, 1, 2) < 1
E        +  where all(0, 1, 2) = all_match(range(0, 3))
E        +    where range(0, 3) = range(3)

How about a more complex example? Asserting attributes of a class instance is pretty common.

    def test_attr_of_classes_without_iterassert() -> None:
        foos = [Foo(1), Foo(2), Foo(3)]
>       assert all(foo.bar < 3 for foo in foos)
E       assert False
E        +  where False = all(<genexpr> at 0x10597ca50>)

iterassert makes it easy to apply functions to the iterable, and will convince pytest to show you the result of that function!

    def test_attr_of_classes_with_iterassert() -> None:
        foos = [Foo(1), Foo(2), Foo(3)]
>       assert all_match(foos, get_bar) < 3
E       assert all(9001, 9002, 9003) < 3
E        +  where all(9001, 9002, 9003) = all_match([<Foo(1)>, <Foo(2)>, <Foo(3)>], get_bar)

Even the test summary says it all:

FAILED example.py::test_generator_without_iterassert - assert False
FAILED example.py::test_generator_with_iterassert - assert all(0, 1, 2) < 1
FAILED example.py::test_attr_of_classes_without_iterassert - assert False
FAILED example.py::test_attr_of_classes_with_iterassert - assert all(9001, 9002, 9003) < 3

pytest-iterassert is on PyPI, so you can simply install via pip install pytest-iterassert (requires Python 3.6 or higher).

Development

This library uses Poetry for managing dependencies. You just need to run poetry install, and it will create a virtual environment with all developer dependencies installed.

Please run poetry run ./lint before submitting pull requests.

License

This library is licensed under the Mozilla Public License Version 2.0. For more information, see LICENSE.