How to run tests without installing package?

Question

I have some Python package and some tests. The files are layed out following http://pytest.org/latest/goodpractices.html#choosing-a-test-layout-import-rules Putting tests into an extra directory outside your actual application code, useful if you have many functional tests or for other reasons want to keep tests separate from actual application code (often a good idea): ``` setup.py # your distutils/setuptools Python package metadata mypkg/ __init__.py appmodule.py tests/ test_app.py ``` My problem is, when I run the tests `py.test`, I get an error ImportError: No module named 'mypkg' I can solve this by installing the package `python setup.py install` but this means the tests run against the installed package, not the local one, which makes development very tedious. Whenever I make a change and want to run the tests, I need to reinstall, else I am testing the old code. What can I do?

Accepted Answer

I know this question has been already closed, but a simple way I often use is to call `pytest` via `python -m`, from the root (the parent of the package).

```
$ python -m pytest tests
```

This works because `-m` option adds the current directory to the python path, and hence `mypkg` is detected as a local package (not as the installed).

See: https://docs.pytest.org/en/latest/usage.html#calling-pytest-through-python-m-pytest

How to run tests without installing package?

Solution

Problem