`python -m unittest discover` does not discover tests

Question

Python's unittest discover does not find my tests!

I have been using nose to discover my unit tests and it is working fine. From the top level of my project, if I run nosetests I get:

Ran 31 tests in 0.390s

Now that Python 2.7 unittest has discovery, I have tried using

python -m unittest discover

but I get

Ran 0 tests in 0.000s

My directory structure is:

myproj/
    reporter/
    __init__.py
    report.py
    [other app modules]
        tests/
        __init__.py
        test-report.py
        [other test modules]

Do you have any ideas why unittest's discovery algorithm can't find the tests?

I'm using Python 2.7.1 and nose 1.0.0 on Windows 7.

Answer 1

The behaviour is intentional, but the documentation could make this clearer. If you look at the first paragraph in the test discovery section, it says:

For a project’s tests to be compatible with test discovery they must all be importable from the top level directory of the project (in other words, they must all be in Python packages).

A corollary to that is that the file names must also be valid Python module names. test-report.py fails that test, since test-report is not a legal Python identifier.

A docs bug suggesting that this be mentioned explicitly in the documentation for the -p pattern option would probably be a good way forward.

Answer 2

I had this problem because some directories in a project were missing __init__.py. I thought I don't need them in Python 3.7.

Just add __init__.py to every directory and python3 -m unittest will find tests automatically.

Answer 3

As someone relatively new to Python, the naming convention in the docs implied the opposite. Ben's comment was very helpful: the default discovery pattern looks for test-modules prefixed with the string "test"

I thought the introspection would just look for class names and not require a specific file naming convention.

Here is what the docs say: https://docs.python.org/3/library/unittest.html python -m unittest discover -s project_directory -p "_test.py" I couldn't get this to work, but by changing my file names to be "test_.py" - success!

Answer 4

This got me as well. This explains the unittest discovery in detail https://docs.python.org/3/library/unittest.html#test-discovery

To make python -m unittest auto find your tests, you need to do 2 things. 1) add a blank __init__.py file to the tests folder, and 2) name your test 'test_some_name.py'. unittest looks for the file name to START with 'test'. You can change that with the '-p' flag if you want, which is explained in the link above.

Here is my folder strucutre.

MyProject
  /src
    my_file.py
  /tests
    __init__.py
    test_my_file.py

Then I run 'python -m unittest' from the MyProject directory.

Here is an example of refrencing the src file from test_my_file.py:

import unittest
from src import my_file as MF

class TestMyFileMethods(unittest.TestCase):

    def test_some_method(self) :
        self.assertTrue(True)

    #... more tests ...

if __name__ == '__main__':
    unittest.main()