Do you mean container? So you'd like to have your long running dev container, and a separate test container that keeps running but you only use it every now and then, right? Because you neither want to include the test stuff in your dev container, nor use file watchers for the tests?
Then while I don't know your exact environment and flow, could you start the container with `docker run ... sh -c "while true; do sleep 1; done"` to "keep it warm" and then `docker exec ...` to run the tests?
Do you mean container? So you'd like to have your long running dev container, and a separate test container that keeps running but you only use it every now and then, right? Because you neither want to include the test stuff in your dev container, nor use file watchers for the tests?
Then while I don't know your exact environment and flow, could you start the container with `docker run ... sh -c "while true; do sleep 1; done"` to "keep it warm" and then `docker exec ...` to run the tests?