Django Test unittest.loader.ModuleImportFailure

I can't import my models in my tests directory, this is my error :

======================================================================
ERROR: tests.test_views (unittest.loader.ModuleImportFailure)
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ImportError: Failed to import test module: tests.test_views
Traceback (most recent call last):
  File "C:\Python27\lib\unittest\loader.py", line 254, in _find_tests
    module = self._get_module_from_name(name)
  File "C:\Python27\lib\unittest\loader.py", line 232, in _get_module_from_name
    __import__(name)
  File "c:\wamp\www\km0\tests\test_views.py", line 3, in <module>
    from .models import Entreprise
  File "c:\wamp\www\km0\tests\models.py", line 6, in <module>
    class Entreprise(models.Model):
  File "C:\Python27\lib\site-packages\django-1.9.5-py2.7.egg\django\db\models\ba
se.py", line 102, in __new__
    "INSTALLED_APPS." % (module, name)
RuntimeError: Model class tests.models.Entreprise doesn't declare an explicit ap
p_label and isn't in an application in INSTALLED_APPS.


----------------------------------------------------------------------
Ran 1 test in 0.000s

FAILED (errors=1)
Preserving test database for alias 'default' ('test_km0')...

I did some research and couldn't find an answer ...

test_views.py :

from django.test import TestCase
import unittest
from .models import Entreprise

class Km0ViewsTestCase(TestCase):
    def test_cart(self):
        resp = self.client.get('/fr/cart/')
        self.assertEqual(resp.status_code, 200)
        resp = self.client.get('/en/cart/')
        self.assertEqual(resp.status_code, 200)
        resp = self.client.get('/de/cart/')
        self.assertEqual(resp.status_code, 200)

My directory : my directory

Thanks in advance for your help !