Hi Daniel, On Sat, Dec 29, 2012 at 18:11 +0100, Daniel Neuhäuser wrote: > Hello, > > I have recently re-discovered py.test searching for testing solution for a > new project and have started using it in said project. However I have also > noticed that fixtures are rather heavily constrained, most importantly in > that a fixture cannot have multiple values. > > To give an example one of the things that are part of my new project is > password hashing. What I would like to be able to do with fixtures is have > a fixture `password` that creates several random passwords and I would like > a test that uses the fixture to be called with each of these passwords.
Did you check out http://pytest.org/latest/fixture.html#parametrizing-a-fixture yet ? > Furthermore I would like to be able to create other fixtures such as a > `pw_hash` fixture that depends on the `password` fixture and creates hashes > for each password. That is directly doable like so: @pytest.fixture(params=["pass1", "pass2"] def password(request): return request.param @pytest.fixture def pw_hash(password): return hash(password) This would make all tests that use "pw_hash" run twice. > I would also like to be able to write tests that take multiple fixtures and > while being parametrized "naturally". An example would be a function > `test_pw_hash_verify(pw_hash, password)` that takes both two fixtures > `pw_hash` and `password`. In this case I would like `test_pw_hash_verify` > to be called with password and the corresponding `pw_hash`. This so far sounds like the current scheme. > > In more abstract terms I would like to have a fixture system for which the > following rules hold: > > - A fixture `fixture()` represents set of values. > - A fixture `fixture(a)` is a n:n (n:m?) mapping of the values represented > by `a` to a new set of values. > - A fixture `fixture(*fixtures)` is a n:m mapping of the cartesian product > of the values represented by each in `fixtures` if they are all independent > from one another. If any fixture `a` in `fixtures` is dependent upon one or > more other fixtures `b_` in `fixtures` `fixture(*fixtures)` shall only be > called with the values of `a` and `b_` so that the values `a` was called > with are equal to the ones `fixtures(*fixtures)` is called with. > > I have created a very simple implementation of this algorithm to play > around with as an example, which I hope will better illustrate the idea: > https://gist.github.com/4408054 This particular API is not supported, i.e. yielding from fixtures. pytest follows a design decision that collection of tests should be independent from running or setting up tests. At collection time pytest has a view on the complete fixture tree neccessary for running the tests and re-orders tests to be grouped by fixtures/scopes. Yielding fixtures would not allow either. > What I would like to know is whether there is any convenient way to do that > now without abusing py.test significantly, whether anyone is working on > this or something equivalent already or if there is some huge flaw in this > idea, that I am missing at the moment. Let us know if the above methods work for you or what is missing! cheers, holger > _______________________________________________ > Pytest-dev mailing list > Pytest-dev@python.org > http://mail.python.org/mailman/listinfo/pytest-dev _______________________________________________ Pytest-dev mailing list Pytest-dev@python.org http://mail.python.org/mailman/listinfo/pytest-dev
