request to localhost (Node.js server) returns ECONNREFUSED in travis ci

I am developing a server using nodejs and express, I use newman package (postman's node library) for testing. To run the tests I setup the server and then make requests using newman.
All works fine on my PC, but when I try to run the test on travis ci I get
Error connect ECONNREFUSED 127.0.0.1:3000.

How can I fix the issue? I think this is related to how travis ci handles VM, but can't find a solution.

github repository: the tests are in the postman folder and be sure to look at the endpoints branch
travis ci log