pytest

In python everything is an object. I'm sure there are minor exceptions or arguable cases but that's also the case with Ruby. Most infamously with Proc. Classes are objects in python, usually instances of class called type or a subclass of type(usefulfor controlling class creation), this is called the metaclass. A constructor call MyObject() is basically just the __call__ method of the metaclass. Modules are also objects usually of type types.ModuleClass or a subclass although really you can stick any object in sys.modules dictionary and have it act like a module and import it. Sure it doesn't use messages instead attributes whether field or methods both go through the same lookup method __getattribute__ which goes up the class inheritance chain in an OO manner. There's also __getattr__ for more method_missing like access instead of overr

In Python, some of the stated use cases, like extracting coverage, extracting the call graph, etc, you can get via tracing already (sys.settrace, https://docs.python.org/3/library/sys.html#sys.settrace). And I would argue, the other stated use cases are maybe interesting to play around with, but nothing you really would want in production (I suppose). Some of the other use cases, you can also achieve by module import hooks and rewriting the AST. (E.g. see how PyTest rewrites the assertion AST to produce nice error messages: https://github.com/pytest-dev/pytest/blob/main/src/_pytest/a...)

Is there a reason you need specialized assertions over something like Python's generic assert? >>> big = 2; small = 3 >>> assert big >= small, "big is smaller than small" Traceback (most recent call last): File "<stdin>", line 1, in <module> AssertionError: big is smaller than small In pytest, assertions are rewritten[1] to return something more useful like: def test(): big = 2 small = 3 > assert big > small E assert 2 > 3 test/test_dumb.py:4: AssertionError ========== short test summary info ========== FAILED test/test_dumb.py::test - assert 2 > 3 1: https://github.com/pytest-dev/pytest/blob/f373974707f57a0b28...

I absolutely agree about fixtures-as-arguments thing. Ward does this a lot better, using default values for the fixture factory. There's a long issue on ideas to implement something like that as a pytest plugin (https://github.com/pytest-dev/pytest/issues/3834), but it seems the resulting plugin relies on something of a hack.

that doesn't make much sense and there are necessary uses for eval() /exec(), mostly for dynamic creation of code: For example here's Python dataclasses in the standard library using exec() to create the `__init__` and other methods that go on your dataclass: https://github.com/python/cpython/blob/main/Lib/dataclasses.... Here's Pydantic using it for a jupyter notebook check: https://github.com/pydantic/pydantic/blob/594effa279668bd955... here's Pytest using it to rewrite modules so that functions like assert etc. are instrumented by pytest: https://github.com/pytest-dev/pytest/blob/eca93db05b6c5ec101... Here's the decorator module using it (as is the only way to do this in Python) to create a signature matching decorator for an arbitrary function: https://github.com/micheles/decorator/blob/ad013a2c1ad796996... All of these libraries are

py.test has a different way of finding tests. It loads Python files starting with "test_" or ending in "_test.py" then uses reflection, to find functions starting with "test_" or classes starting with "Test", or functions marked with the attribute "__test__" (which is applied by the @nose.tools.istest decorator). See https://github.com/pytest-dev/pytest/blob/d69abff2c7de8bc65b... This mechanism of scanning the AST is a different approach and won't find the same set of tests. Scanning the AST can be useful and things like https://macropy3.readthedocs.io/en/latest/ are awesome though!

Sorry for not being clear. This is what I was talking about: https://github.com/pytest-dev/pytest/issues/916 It is a known issue. Basically your fixture/setup/teardown, which you expect should run for every example generated by Hypothesis, actually only run once.

I feel very uncomfortable whenever I read a code-of-conduct, including the PyTest one: https://github.com/pytest-dev/pytest/blob/master/CODE_OF_CON... I don’t think there’s anything wrong at all with the spirit of such documents, but they seem to normalize a world where bad behavior is regulated by well-intentioned ad hoc legalese. In the good old days, one would receive on the spot practical training on how to behave by ones parents, friends, older siblings, teachers etc. I suspect my revulsion at reading codes of conducts is part of me being in denial that there are so many more people in the world now, on the internet, who were raised by the social / etiquette equivalent of animals.