Добавил раннер для тестов

core/tests/runner.py

@@ -0,0 +1,18 @@
+import os
+import shutil
+
+from django.test.runner import DiscoverRunner
+from django.conf import settings
+
+
+class TempMediaMixin(DiscoverRunner):
+
+    def setup_test_environment(self, **kwargs):
+        super(TempMediaMixin, self).setup_test_environment()
+        settings._original_media_root = settings.MEDIA_ROOT
+        self._temp_media = '/tmp/test/'
+        settings.MEDIA_ROOT = self._temp_media
+
+    def teardown_test_environment(self, **kwargs):
+        if os.path.exists('/tmp/test/'):
+            shutil.rmtree('/tmp/test/')

project/settings.py

@@ -104,6 +104,8 @@
     },
 ]
 
+TEST_RUNNER = 'core.tests.runner.TempMediaMixin'
+
 
 # Internationalization
 # https://docs.djangoproject.com/en/1.11/topics/i18n/