How to pass command line arguments to Junit Test

It seems counter-intuitive that you want to parameterize your unit tests in this way. I would suggest that you think of a few sets of arguments and hardcode them in your unit tests. This way they are repeatable, and, hopefully, offer good coverage.

You don't need to pass command line parameters to your JUnit execution. Instead your test methods should build/prepare everything and call your new myClass(...) constructor with the parameters your original program would do when using command line parameters. The code might look like this:

@Test
public void checkForWhatever() {
    // prepare everything here like create a temp file
    File x = ...;
    String filename = x.getName(); // or maybe even x.getAbsolutePath();
    String[] arguments = new String[1];
    arguments[0] = filename;
    // now call your constructor
    myClass obj = new myClass(arguments);
    // do any checks here now
    Assertions.assertTrue(obj.getWhatever());
    // ...
}