You need to specify the list of arguments as if you were giving it at the command line:
Mix.Tasks.Test.run(["--only", "test/test_only_profile_trest.exs"])
Aside of that, --only filters based on @tags, you probably want to pass only the file to run tests from:
Mix.Tasks.Test.run(["test/test_only_profile_trest.exs"])
Finally, I do think you have a typo in the filename 
