404 "not found on 1st express endpoint test

Maybe it's me but, by using supertest and mocha to test an express server.

Issue :
The 1st express endpoint test of a list of test always returns a 404 "not found". and the following tests function nominally

Temporary Fix :
Add a test, testing nothing before any other test ( and then the orignal one doesn't throw back a 404 "not found" anymore)

This blocked me for so long, the express server routes are fine, but i don't know if this issue can be fixed properly.