IndexError: list index out of range in Test case - django

Question

I have strange problems
I have next code Using TesCase and APIClient to get request with token
class Profile(TestCase):
fixtures = ['profiles.json']
def setUp(self):
self.client = APIClient()
self.user = Profile.objects.get(username='some-username')
self.token = Token.objects.create(user=self.user)
self.client.credentials(HTTP_AUTHORIZATION='Token ' + self.token.key)
def test_profile(self):
response = self.client.get('/api/some-username/profile/')
print(response.status_code)
print(response.data)`
Authorization goes well,but the I received error. If i use requests.get with headers (token) to development django server all pass well i receive a correct json response
Full Traceback when i run this test:
Traceback (most recent call last):
File "/home/work/project/profiles/tests.py", line 103, in test_user_profile
response = self.client.get('/api/some-username/profile/')
File "/usr/local/lib/python3.5/dist-packages/rest_framework/test.py", line 291, in get
response = super(APIClient, self).get(path, data=data, **extra)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/test.py", line 208, in get
return self.generic('GET', path, **r)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/test.py", line 237, in generic
method, path, data, content_type, secure, **extra)
File "/usr/local/lib/python3.5/dist-packages/django/test/client.py", line 416, in generic
return self.request(**r)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/test.py", line 288, in request
return super(APIClient, self).request(**kwargs)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/test.py", line 240, in request
request = super(APIRequestFactory, self).request(**kwargs)
File "/usr/local/lib/python3.5/dist-packages/django/test/client.py", line 501, in request
six.reraise(*exc_info)
File "/usr/local/lib/python3.5/dist-packages/django/utils/six.py", line 686, in reraise
raise value
File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/exception.py", line 41, in inner
response = get_response(request)
File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 187, in _get_response
response = self.process_exception_by_middleware(e, request)
File "/usr/local/lib/python3.5/dist-packages/django/core/handlers/base.py", line 185, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/usr/local/lib/python3.5/dist-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
return view_func(*args, **kwargs)
File "/usr/local/lib/python3.5/dist-packages/django/views/generic/base.py", line 68, in view
return self.dispatch(request, *args, **kwargs)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/views.py", line 489, in dispatch
response = self.handle_exception(exc)
File "/usr/local/lib/python3.5/dist-packages/rest_framework_tracking/mixins.py", line 69, in handle_exception
response = super(BaseLoggingMixin, self).handle_exception(exc)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/views.py", line 449, in handle_exception
self.raise_uncaught_exception(exc)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/views.py", line 486, in dispatch
response = handler(request, *args, **kwargs)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/generics.py", line 254, in get
return self.retrieve(request, *args, **kwargs)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/mixins.py", line 58, in retrieve
return Response(serializer.data)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/serializers.py", line 533, in data
ret = super(Serializer, self).data
File "/usr/local/lib/python3.5/dist-packages/rest_framework/serializers.py", line 262, in data
self._data = self.to_representation(self.instance)
File "/usr/local/lib/python3.5/dist-packages/rest_framework/serializers.py", line 500, in to_representation
ret[field.field_name] = field.to_representation(attribute)
File "/home/work/project/profiles/serializers.py", line 10, in to_representation
return institute.all()[0].slug
File "/usr/local/lib/python3.5/dist-packages/django/db/models/query.py", line 289, in __getitem__
return list(qs)[0]
IndexError: list index out of range
How know what is the problem?