Coverage.py does not discover tests without init.py file in sub directories

Question

When I run coverage for python, I always need an empty __init__.py file in the tests sub-directory to get coverage to run the tests. This is a requirement for python2 packages, but not for python3. To reproduce, I did the following (pre-requisites are python3, pip3 and brew):

Run the following terminal command:
```
pip3 install coverage
```

Create the following directory structure:

example\
    example.py
tests\
    test_example.py

example.py:

#!/usr/bin/env python3
class Example:
    value = 3

    def update(self):
        self.value = 4

test_example.py:

#!/usr/bin/env python3

import unittest
from example.example import Example

class TestExample(unittest.TestCase):
    def test_example(self):
        example_object = Example()
        self.assertEqual(3, example_object.value)
        example_object.update()
        self.assertEqual(4, example_object.value)

Run the following terminal command:

coverage run --branch -m unittest discover -s . && coverage report

I should get: Ran 1 test in x.yz seconds, but I always get Ran 0 tests in x.yz seconds, and to fix this, I have to add __init__.py files to both directories. How can I run coverage without needing the init files?

Please let me know if you need anything else from me regarding this question. I would appreciate any help!

Ned Batchelder · Accepted Answer · 2017-12-05 02:36:09Z

1

Although Python 3 doesn't need __init__.py files, omitting them creates namespace packages, which are not a good idea if you don't need them. For example, they are read last, so even directories later in the PYTHONPATH can shadow your files.

You should create the __init__.py files anyway.

answered Dec 5, 2017 at 2:36

Ned Batchelder

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2 Comments

Steve Over a year ago

Eventually, I would want to add more directories to the structure indicated in 2, like example2/example2SubDir/example2.py, and example3/example3.py. I would also add test files for these. Based on what I read about namespace packages, and this particular comment: stackoverflow.com/a/21819733/5560776 it seems like I would need to add the init files for my example, correct?

Ned Batchelder Over a year ago

The best practice is to put an __init__.py file into any directory you want to be able to import.

f_squared · Accepted Answer · 2019-12-30 12:01:07Z

1

The exact path to the tests folder from the top has to be specified. For example:'python3 -m unittest discover src/main/python/tests'

Its most likely a bug with 'unittest discovery' where discovery works when you explicitly specify namespace package as a target for discovery.

But it does not recurse into any namespace packages inside namespace_pkg. So when you simply run 'python3 -m unittest discover' it doesn't go under all namespace packages (basically folders) in cwd.

Some PRs are underway(for example:issue35617) to fix this, but are yet to be released

answered Dec 30, 2019 at 12:01

f_squared

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