add a test for new pargs.py

I'm learing github actions and codecov integration. My comit not passing
CI because my new code doesn't have enough test coverage.
🧠++

tests/test_args.py

@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+# test pargs.py to make codecov happy
+
+import pytest
+
+from pymake import pargs
+
+def test_usage():
+    pargs.usage()
+
+def test_args():
+    a = pargs.Args()
+
+@pytest.mark.skip(reason="sys.exit causes pytest to error")
+def test_parse_args_help():
+    args = pargs.parse_args(('-h',))
+    args = pargs.parse_args(('--help',))
+
+def test_parse_args_always_make():
+    args = pargs.parse_args(('-B', '-f', '/dev/null'))
+    assert args.always_make
+
+    args = pargs.parse_args(('--always-make', '-f', '/dev/null'))
+    assert args.always_make
+
+def test_parse_args_file():
+    args = pargs.parse_args(('-f', '/dev/null'))
+    assert args.filename == "/dev/null"
+
+    args = pargs.parse_args(('--file', '/dev/null'))
+    assert args.filename == "/dev/null"
+
+    args = pargs.parse_args(('--makefile', '/dev/null'))
+    assert args.filename == "/dev/null"
+
+def test_parse_args_sexpr():
+    args = pargs.parse_args(('-S', '-f', '/dev/null'))
+    assert args.filename == "/dev/null"
+    assert args.s_expr
+
+def test_no_builtin_rules():
+    args = pargs.parse_args(('-r', '-f', '/dev/null'))
+    assert args.filename == "/dev/null"
+
+    args = pargs.parse_args(('--no-builtin-rules', '-f', '/dev/null'))
+    assert args.filename == "/dev/null"
+    assert args.no_builtin_rules
+