Hi Chris, thank you for your work on this.

When I run:

docker-compose -f docker-compose.phpunit.yml run --rm wordpress_phpunit phpunit

I get this error:

Error response from daemon: OCI runtime create failed: container_linux.go:344: starting container process caused "exec: \"phpunit\": executable file not found in $PATH": unknown 

I've done some digging and can't figure out why. Do you have any ideas?