implementation of IS_RUNNING and IS_LISTENING_ON_PORT failed

[xinity]

been working on implementing both (IS_RUNNING and IS_LISTENING_ON_PORT)

problem is at build time, cmd/entrypoint dockerfile instructions are not triggered, so we can't easily implement these tests.

i've tried to find an easy and clean way to trigger CMD/ENTRYPOINT instructions and then fire up tests, but failed.

a clean way is to trigger a "docker run -d" of the tested container at @DOCKER_RUN instruction in the Dockerfile_test using docker go client.

any clue appreciated :)