Integration tests in monolithic applications is complicated as there might be a database that needs to be populated and there might be third party systems that need to be running in order to test all functionalities. In microservices architecture, it is even worse as there are more services that need to be running together in order to test a single service. For simple application which consists only several services, it is OK to be tested on developers laptop or desktop with docker compose. If the application involves dozens services and most services have their own databases, then it must be tested in a cloud environment.
In order to test our own libraries and services, we have developed light-bot and one of the features is to checkout develop branch for all repositories and build/test them all by starting all servers together.