Fix tests on MacOS

tests/conftest.py

@@ -15,14 +15,20 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+
 import pytest
 import socket
 import asyncio
 import tempfile
 import shutil
 import os
+import sys
 from aiohttp import web
 
+sys._called_from_test = True
+# Prevent execution of external binaries
+os.environ["PATH"] = tempfile.mkdtemp()
+
 from gns3server.config import Config
 from gns3server.web.route import Route
 # TODO: get rid of *
@@ -33,10 +39,6 @@ from gns3server.modules.project_manager import ProjectManager
 from tests.handlers.api.base import Query
 
 
-# Prevent execution of external binaries
-os.environ["PATH"] = tempfile.mkdtemp()
-
-
 @pytest.yield_fixture
 def restore_original_path():
     """