opencsd: tests: Update test script

In the python test script ensure that only options after '--' are passed
through to the trc_pkt_lister program.

Unknown options before this will now result in a error and the script
will fail

Signed-off-by: Mike Leach <mike.leach@arm.com>

Author: mikel-armbb

decoder/docs/test_progs.md

@@ -94,14 +94,18 @@ __Runner options__
 - `--memacc-req-trace` : set `OPENCSD_MEMACC_REQ_TRACE=1` for all test processes started by the script.
 - `--diff-only` : run only the result comparison step without running any tests.
 
-Any additional arguments after the script options are passed through to
-`trc_pkt_lister`. Use `--` to separate runner options from the packet lister
-arguments when needed.
+Any additional arguments for `trc_pkt_lister` must appear after `--`. The
+Python runner validates all options before `--`, and any unknown option there
+is treated as an error instead of being passed through.
 
 Example:
 
 `python .\decoder\tests\run_pkt_decode_tests.py --suite ete -- --stats`
 
+This will fail because `--stats` is before `--`:
+
+`python .\decoder\tests\run_pkt_decode_tests.py --suite ete --stats`
+
 __Result comparison__
 
 The script can compare the results created by the current run against a

decoder/tests/run_pkt_decode_tests.py

@@ -908,6 +908,7 @@ def run_ete_suite(
 def parse_args(argv: Sequence[str]) -> tuple[argparse.Namespace, list[str]]:
     parser = argparse.ArgumentParser(
         description="Run OpenCSD packet decode regression tests on Linux, macOS, or Windows.",
+        epilog="Pass additional trc_pkt_lister arguments only after '--'.",
     )
     parser.add_argument(
         "--suite",
@@ -977,9 +978,14 @@ def parse_args(argv: Sequence[str]) -> tuple[argparse.Namespace, list[str]]:
         help="Set OPENCSD_MEMACC_REQ_TRACE=1 for every test process started by this runner.",
     )
 
-    namespace, passthrough = parser.parse_known_args(argv)
-    if passthrough and passthrough[0] == "--":
-        passthrough = passthrough[1:]
+    passthrough: list[str] = []
+    parseable_argv = list(argv)
+    if "--" in parseable_argv:
+        separator_index = parseable_argv.index("--")
+        passthrough = parseable_argv[separator_index + 1 :]
+        parseable_argv = parseable_argv[:separator_index]
+
+    namespace = parser.parse_args(parseable_argv)
 
     diff_results_suffixes = namespace.diff_results_suffix or []
     if namespace.diff_previous and diff_results_suffixes: