def test_ls_filename(self):
        """test 'ls file1.txt file2.txt' showing 'file1.txt file2.txt'"""
        output = self.run_command("ls file1.txt file2.txt", exitcode=0)
        self.assertIn("file1.txt", output)
        self.assertIn("file2.txt", output)
        self.assertNotIn("otherfile.txt", output)
test 'ls file1.txt file2.txt' showing 'file1.txt file2.txt'
tests/ls/test_ls.py