add_specific_doctest.rst

Hack for py.test to programmatically add doctests from an explicitly specified module (as opposed to a package or glob pattern specified on the command line).

Define a conftest.py which instructs py.test to collect the doctests from a specific module when the conftest.py file itself is collected.

conftest.py

def pytest_collect_file(parent, path):
    """Add doctests from a specific module when this suite runs"""

    # This guard ensures the doctests are only added once: add the doctests
    # when *this* file (conftest.py) is "collected" by py.test, which only
    # happens once
    if __file__ == str(path):
        from pkg_resources import resource_filename
        from _pytest.doctest import DoctestModule
        
        module_file = resource_filename('package.subpackage', 'module.py')
        
        return DoctestModule(module_file, parent)