Running nose tests with plugins using the setuptools test command

The nose Python test framework is a really good choice for writing and running your tests. However, it seems that the author is deprecating the use of nose.collector which was used when running the test setuptools command:

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python setup.py test

Furthermore, even in its current form, the nose collector doesn’t correctly work with plugins such as coverage.py.

The recommended way is to use the nosetests setuptools command instead. Though, this presents several problems:

The nosetests setuptools command is not recognised unless nose is installed

The only way to ensure that nose is installed is using the setup_requires directive

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setup(
    ...
    setup_requires=[
        'nose',
        'coverage',
        'mock'
    ],
    ...
)

Using the setup_requires directive means that every time a user installs your package using pip, they must also download all the setup dependencies, which they don’t actually need to use the library. The setup_requires dependencies are not installed, but is still a waste of time and bandwidth for our users.

So how do we get around this? We create a custom test command! This is based on py.test’s excellent example.

In setup.py:

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from setuptools import setup
from setuptools.command.test import test as TestCommand


# Inspired by the example at https://pytest.org/latest/goodpractises.html
class NoseTestCommand(TestCommand):
    def finalize_options(self):
        TestCommand.finalize_options(self)
        self.test_args = []
        self.test_suite = True

    def run_tests(self):
        # Run nose ensuring that argv simulates running nosetests directly
        import nose
        nose.run_exit(argv=['nosetests'])

setup(
    ...
    tests_require=[
        'nose',
        'coverage',
        'mock'
    ],
    cmdclass={'test': NoseTestCommand},
    ...
)

And there we have it, a custom test command which runs our nose tests after test dependencies are installed. This combats all the problems mentioned above and also correctly detects plugins in setup.cfg.

Here’s the setup.cfg for my Painter project which I tested with:

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[nosetests]
detailed-errors=1
with-coverage=1
cover-package=painter
cover-erase=1
verbosity=2

In the future, I’ll likely be switching to py.test as my test runner anyway due its improved assert introspection. But for now, this will get me by.

Hope this is helpful :)