How to interact between multiple docker containers, eg ubuntu container with selenium hub container - selenium

Question

I have the following three docker containers
1. Ubuntu Container with Mono that has selenium scripts(DLL)
2. Selenium Hub Container
3. Selenium Chrome Node Container
when I build the Docker Compose File, All three containers are up and running, the Ubuntu container exits after sometime without executing any tests.Any idea on how to implement this?
I am executing the tests in the Ubuntu container using mono and would like to create a docker image once this works. Any explanation or sample code on this would be really great.
I have created a bridge and have assigned static ip to all three containers.
Docker Compose File:
version: '3.7'
services:
seleniumhub:
image: selenium/hub
container_name: hubcontainer
networks:
ynetwork:
ipv4_address: 172.21.0.2
ports:
- "4444:4444"
privileged: true
nodechrome:
image: selenium/node-chrome-debug
container_name: chromecontainer
volumes:
- /dev/shm:/dev/shm
depends_on:
- seleniumhub
environment:
- HUB_HOST=seleniumhub
- HUB_PORT=4444
- NODE_MAX_INSTANCES=5
- NODE_MAX_SESSION=5
- START_XVFB=false
networks:
ynetwork:
ipv4_address: 172.21.0.10
Mytests:
container_name: Myubuntutests
depends_on:
- seleniumhub
- nodechrome
networks:
ynetwork:
ipv4_address: 172.21.0.11
build:
context: .
dockerfile: ubuntu.Dockerfile
networks:
ynetwork:
name: ytestsnetwork
driver: bridge
ipam:
config:
- subnet: 172.21.0.0/16
Docker File ubuntu.Dockerfile
FROM ubuntu
COPY /bin/Debug/ /MyTests
ENV DEBIAN_FRONTEND=noninteractive
ENV TZ=Asia/Tokyo
RUN ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && echo $TZ > /etc/timezone && apt-get update && apt-get clean && apt-get install -y wget && apt-get install -y curl && apt-get install -y nuget && apt-get install -y mono-complete && apt-get update && nuget update -self && nuget install testrunner
WORKDIR "/MyTests"
ENTRYPOINT mono /TestRunner.1.8.0/tools/testrunner.exe MyTests.dll
Docker Compose commands used (tried):
docker-compose up --build
docker-compose up --build -d
I expect the Docker Compose to Build all three containers and execute the tests and exit once done