test: add small test for argument parsing

This is just a small detail, but in some way CLI options are similar
to public API. I did this while trying some changes, even if in the
end the issue to solve was not in pmbootstrap, I thought it'd make
sense to contribute this.

Part-of: https://gitlab.postmarketos.org/postmarketOS/pmbootstrap/-/merge_requests/2626

test/parse/test_arguments.py

@@ -0,0 +1,19 @@
+# Copyright 2025 Pablo Correa Gomez
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from pmb.parse import get_parser
+
+
+def test_chroot_simple():
+    parser = get_parser()
+    args = parser.parse_args("chroot ls".split())
+    assert args.action == "chroot"
+    assert args.command == ["ls"]
+
+
+def test_chroot_args():
+    parser = get_parser()
+    args = parser.parse_args("chroot --rootfs -- ls -l".split())
+    assert args.action == "chroot"
+    assert args.rootfs is True
+    assert args.command == ["ls", "-l"]