Run mocha unit-test on docker-compose images - node.js

Question

I have an api in nodeJs, which run under micro-services.
So far it work, what i want to do next is to be able to run unit-test (mocha) on those images.
docker-compose.yml:
version: '3'
services: db:
image: mongo
ports:
- 27017:27017
db-seeds:
build: ./services/mongo-seeds
links:
- db
gateway:
build: ./services/gateway
ports:
- 4000:4000
depends_on:
- A
- B
- C
A:
build: ./services/A
ports:
- 4003:4000
depends_on:
- db
B:
build: ./services/B
ports:
- 4001:4000
depends_on:
- db
C:
build: ./services/C
ports:
- 4002:4000
depends_on:
- db
One of a DockerFile:
FROM node:latest
COPY . /src
WORKDIR /src
RUN yarn
EXPOSE 4000
CMD yarn start
What i did so far is to make another docker-compose file which will run other docker file (DockerFile.test) :
FROM node:latest
COPY . /src
WORKDIR /src
RUN yarn
EXPOSE 4000
CMD yarn test
also tried:
FROM node:latest
COPY . /src
WORKDIR /src
RUN yarn
EXPOSE 4000
CMD yarn start
RUN sleep 240
CMD yarn test
They both fail, at this point yarn test is launch before my gateway and servers are up. What i want to do, is to launch my servers and then run my unit-test in the images, but i'm new to docker and lack knowledge on how to implement that.
yarn test:
"test": "NODE_ENV=test ./node_modules/.bin/mocha"

Answer 1

You have to run mocha on the same host with your docker-compose file. This can be a docker image too (which can be started with docker-compose if you want ;)
You have to run docker-compose with your services before you run yarn test.
Create/Use a Dockerfile with docker and docker-compose and node (for your case)
copy your sources on it (docker-compose.yml and other relevant sources)
run docker-compose up -d on it
run yarn test on it
Tools like CloudFoundry or OpenStack might do this job.
If you are with CloudFoundry I can give you concrete details.
To concatenate several commands use the unix-cli syntax:
RUN docker-compose up -d && \
service1 && \
yarn test