"Installing fixture error: no such table: auth_user" while test run (Django)

I encountered strange issue when running test. I have web app that uses initial data from json. It works perfect if running on server, initial data loads.But when I try run tests.py I get

OperationalError: Problem installing fixture '/path/to/fixtures/initial_data.json': Could not load auth.User(pk=1): no such table: auth_user

in .json there is such fields:

},
"model": "auth.user",
"pk": 1
},

And the error occurs even if I run empty tests.py. What could it be?