Testing node.js server with mongodb fails

Hello,

I am trying to add CI in my GitLab repository that houses a node.js server and mocha tests (found in a file named test.bash).
The server itself builds a local database to execute the tests.
I have installed all the necessary components manually such as redis and mongodb.
Until now, I successfully started the redis-server (using the service redis-server start command)
but I am failing to do the same for mongodb, I get the message that this service is not defined.
Although the mongodb is installed (version 4.0.5) and I can see its binaries, I cannot find it in the /etc/init.d/
directory.
Did anybody face this issue?

Here is my .gitlab-ci.yml file:

cache:
  paths:
    - node_modules/

stages:
  - build
  - test

build:
  stage: build
  image: node:latest
  before_script:
    - apt-get update
  script:
    - npm i

test:
  stage: test
  image: node:latest
  before_script:
    - apt-get update
    - curl https://www.mongodb.org/static/pgp/server-4.0.asc | apt-key add -
    - echo "deb http://repo.mongodb.org/apt/debian stretch/mongodb-org/4.0 main" | tee /etc/apt/sources.list.d/mongodb-org-4.0.list
    - apt-get -y install apt-transport-https
    - apt-get -y install autoconf build-essential
    - apt-get -y install redis-server
    - apt-get install -y mongodb-org=4.0.5 mongodb-org-server=4.0.5 mongodb-org-shell=4.0.5 mongodb-org-mongos=4.0.5 mongodb-org-tools=4.0.5
  script:
    - service redis-server status || service redis-server start
    - service mongod status || service mongod start
    - bash test.sh