You can run multiple ExUnit test lines with the following:
mix test my_app/test/path_to_file_test.exs:123:223:333
Each number prefixed with the colon will be run. The above example results in 3 lines being run, with the following result:
Running tests...
==> my_app
Excluding tags: [:test]
Including tags: [line: "123", line: "223", line: "333"]