py.test does not find tests under a class

Question

I am trying to create test classes that aren’t unittest based.

This method under this class

class ClassUnderTestTests:

    def test_something(self):

cannot be detected and run when you call py.test from the command line or when you run this test in PyCharm (it’s on its own module).

This

def test_something(self):

same method outside of a class can be detected and run.

I’d like to group my tests under classes and unless I’m missing something I’m following the py.test spec to do that.

Environment: Windows 7, PyCharm with py.test set as the test runner.

Asked By: Michael

||

Source

Answer 1

By convention it searches for

Test prefixed test classes (without an init method)

eg.

# content of test_class.py
class TestClass:
    def test_one(self):
        x = "this"
        assert 'h' in x

    def test_two(self):
        x = "hello"
        assert hasattr(x, 'check')

    # this works too
    @staticmethod
    def test_three():
        pass

    # this doesn't work
    #@classmethod
    #def test_three(cls):
    #    pass

See the docs:

Answered By: twil

Answer 2

The accepted answer is not incorrect, but it is incomplete. Also, the link it contains to the documentation no longer works, nor does the updated link in the a comment on that answer.

The current documentation can now be found here. The relevant bits of that doc are:

…

In those directories, search for test_*.py or *_test.py files, imported by their test package name.

From those files, collect test items:

…

test prefixed test functions or methods inside Test prefixed test classes (without an __init__ method)

The key bit that is missing in the accepted answer is that not only must the class name start with Test and not have an __init__ method, but also, the name of the file containing the class MUST be of one of the forms test_*.py or *_test.py.

Where I got tripped up here, and I assume many others will too, is that I generally name my Python source files containing only a class definition to directly mirror the name of the class. So if my class is named MyClass, I normally put its test code in a file named TestMyClass.py. This won’t work with PyTest. To let PyTest do its thing with my test class, I need to name the file for this class test_MyClass.py or MyClass_test.py. I chose the last form so that I generally add a ‘_test‘ suffix to the file names I’d otherwise choose that need to be named so that PyTest will parse them looking for tests.

Answered By: CryptoFool

py.test does not find tests under a class

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