How do I use "discover" to run tests in my "tests" directory?

Question

Using DJango/Python 3.7. I read here -- How do I run all Python unit tests in a directory? that I could use a "discover" command to find tests in a specified directory. I want to have a "tests" folder, so I cretaed one and then ran

(venv) localhost:myproject davea$ python -m unittest discover tests
Traceback (most recent call last):
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/unittest/__main__.py", line 18, in <module>
    main(module=None)
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/unittest/main.py", line 100, in __init__
    self.parseArgs(argv)
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/unittest/main.py", line 124, in parseArgs
    self._do_discovery(argv[2:])
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/unittest/main.py", line 244, in _do_discovery
    self.createTests(from_discovery=True, Loader=Loader)
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/unittest/main.py", line 154, in createTests
    self.test = loader.discover(self.start, self.pattern, self.top)
  File "/usr/local/Cellar/python/3.7.2_2/Frameworks/Python.framework/Versions/3.7/lib/python3.7/unittest/loader.py", line 344, in discover
    raise ImportError('Start directory is not importable: %r' % start_dir)
ImportError: Start directory is not importable: 'tests'

This is odd to me because I have an (empty) init file ...

(venv) localhost:myproject davea$ ls web/tests/
__init__.py  model_tests.py

What else do I need to do to get my test directory recognized?

Edit: Below are the contents of model_tests.py ...

from django.conf import settings
from django.test import TestCase
from django.core import management


def setup():
    print("setup")
    management.call_command('loaddata', 'test_data.yaml', verbosity=0)


def teardown():
    management.call_command('flush', verbosity=0, interactive=False)


class ModelTest(TestCase):

    # Verify we can correctly calculate the amount of taxes when we are working
    # with a state whose tax rates are defined in our test data
    def test_calculate_tax_rate_for_defined_state(self):
        state = "MN"
        income = 30000
        taxes = IndividualTaxBracket.objects.get_taxes_owed(state, income)
        print(taxes)
        self.assertTrue(taxes > 0, "Failed to calucate taxes owed properly.")

Answer 1

I think you are having some confusion about discover command. According to docs.

Unittest supports simple test discovery. In order to be compatible with test discovery, all of the test files must be modules or packages (including namespace packages) importable from the top-level directory of the project (this means that their filenames must be valid identifiers).

It means all the test files must be importable from the directory from which you are running the command (directory that holds your web directory). It make this sure, all test files must be in valid python packages (directories containing __init__.py).

Secondly you are running the command python -m unittest discover tests which is wrong. You don't have to add tests at the end. unittests with discover command support 4 options. You can read more about it here.

I have following directory structure.

 web
    ├── __init__.py
    └── tests
        ├── __init__.py
        └── test_models.py

And I am running following command.

python3 -m unittest discover

With following results.

...
----------------------------------------------------------------------
Ran 3 tests in 0.000s

OK