app /test does not closed if the port is wrong

[johnico]

hi
while I run the react app in test mode, the app still working in development mode a usual and the test did not start or failed
I put port 30030 instead 3000 and nothing happens ( waiting for exit from the regular dev mode )

when I changed back to 3000 the test passed
my package.json

    "start": "cross-env CLIENT_ENV=development craco start",
    "test:e2e:ci": " SERVER_NAME=localhost  start-server-and-test start \"30030\" cypress:headless",

thanks