Report program name as cwltool when invoked as cwl-runner (#1535)

argparse defaults prog to os.path.basename(sys.argv[0]), so running
cwltool through its cwl-runner entry point made --help and error
messages say "usage: cwl-runner ...". Set prog="cwltool" explicitly so
the reference implementation is always identified consistently,
regardless of which entry point was used.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: arimu1

cwltool/argparser.py

@@ -89,6 +89,7 @@ def arg_parser() -> argparse.ArgumentParser:
     )
 
     parser = argparse.ArgumentParser(
+        prog="cwltool",
         formatter_class=RichHelpFormatter,
         description="Reference executor for Common Workflow Language standards. "
         "Not for production use.",

tests/test_toolargparse.py

@@ -1,12 +1,13 @@
 import argparse
+import sys
 from collections.abc import Callable
 from io import StringIO
 from pathlib import Path
 
 import pytest
 
 import cwltool.executors
-from cwltool.argparser import generate_parser
+from cwltool.argparser import arg_parser, generate_parser
 from cwltool.context import LoadingContext
 from cwltool.load_tool import load_tool
 from cwltool.main import main
@@ -278,6 +279,15 @@ def test_argparser_without_doc() -> None:
     assert parser.description is None
 
 
+def test_argparser_prog_is_cwltool(monkeypatch: pytest.MonkeyPatch) -> None:
+    """The program name is reported as ``cwltool`` even when invoked as ``cwl-runner``.
+
+    Regression test for https://github.com/common-workflow-language/cwltool/issues/1535
+    """
+    monkeypatch.setattr(sys, "argv", ["cwl-runner", "--help"])
+    assert arg_parser().prog == "cwltool"
+
+
 @pytest.mark.parametrize(
     "job_order,expected_values",
     [