Development only with testing - no actually running - good practice?

I just started in a new team. My task right now is to bring an old application to their new microservice framework (mostly Java). It runs in quite a complex environment, like consuming other web services, messaging via several queues, and providing an public API for other services to use.

The new thing for me is that their development process doesn't involve an actually running the application even once. Instead they solely do testing: unit tests and integration tests. For the integration tests they employ a couple of docker container that mimic their actual production system. There is no staging system - only the production system, where I have no access.

To me it feels weird to never actually run the application. Is this common? Have you guys encountered the same? Is this considered a good practice?