add test for init (thanks Ashwin)

tests/test_mpsd_software.py

@@ -589,6 +589,15 @@ def test_argument_parsing_logic(mocker):
         "mpsd_software_manager.mpsd_software.get_root_dir", return_value=Path(".")
     )
 
+    sys.argv = ["mpsd-software-tests", "init"]
+    mock = mocker.patch(
+        "mpsd_software_manager.mpsd_software.initialise_environment", return_value=None
+    )
+    with pytest.raises(SystemExit):
+        mod.main()
+    call_argument = mock.call_args[0][0]
+    assert isinstance(call_argument, Path)
+
     ### available
     sys.argv = ["mpsd-software-tests", "available"]
     mock = mocker.patch(