gh-131524: Update platform CLI to use argparse

Lib/platform.py

@@ -1464,9 +1464,26 @@ def invalidate_caches():
 
 ### Command line interface
 
-if __name__ == '__main__':
-    # Default is to print the aliased verbose platform string
-    terse = ('terse' in sys.argv or '--terse' in sys.argv)
-    aliased = (not 'nonaliased' in sys.argv and not '--nonaliased' in sys.argv)
+def _parse_args(args: list[str] | None):
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument("args", nargs="*", choices=["nonaliased", "terse"])
+    parser.add_argument("--terse", action="store_true")
+    parser.add_argument("--nonaliased", dest="aliased", action="store_false")
+
+    return parser.parse_args(args)
+
+
+def _main(args: list[str] | None = None):
+    args = _parse_args(args)
+
+    terse = args.terse or ("terse" in args.args)
+    aliased = args.aliased and ('nonaliased' not in args.args)
+
     print(platform(aliased, terse))
+
+
+if __name__ == "__main__":
+    _main()
     sys.exit(0)

Lib/test/test_platform.py

@@ -1,11 +1,16 @@
+import io
+import itertools
 import os
 import copy
+import contextlib
 import pickle
 import platform
 import subprocess
+import shlex
 import sys
 import unittest
 from unittest import mock
+from textwrap import dedent
 
 from test import support
 from test.support import os_helper
@@ -741,5 +746,78 @@ def test_parse_os_release(self):
         self.assertEqual(len(info["SPECIALS"]), 5)
 
 
+class CommandLineTest(unittest.TestCase):
+    def setUp(self):
+        self.clear_caches()
+        self.addCleanup(self.clear_caches)
+
+    def clear_caches(self):
+        platform._platform_cache.clear()
+        platform._sys_version_cache.clear()
+        platform._uname_cache = None
+        platform._os_release_cache = None
+
+    @staticmethod
+    def text_normalize(string):
+        """Dedent *string* and strip it from its surrounding whitespaces.
+        This method is used by the other utility functions so that any
+        string to write or to match against can be freely indented.
+        """
+        return dedent(string).strip()
+
+    def invoke_platform(self, *flags):
+        output = io.StringIO()
+        with contextlib.redirect_stdout(output):
+            platform._main(args=flags)
+        return self.text_normalize(output.getvalue())
+
+    def test_unknown_flag(self):
+        with self.assertRaises(SystemExit):
+            # suppress argparse error message
+            with contextlib.redirect_stderr(io.StringIO()):
+                _ = self.invoke_platform('--unknown')
+
+    def test_invocation(self):
+        flags = (
+            "--terse", "--nonaliased", "terse", "nonaliased"
+        )
+
+        for r in range(len(flags) + 1):
+            for combination in itertools.combinations(flags, r):
+                self.invoke_platform(*combination)
+
+    def test_arg_parsing(self):
+        # Due to backwards compatibility, the `aliased` and `terse` parameters
+        # are computed based on a combination of positional arguments and flags.
+        #
+        # This test tests that the arguments are correctly passed to the underlying
+        # `platform.platform()` call. The parameters are two booleans for `aliased`
+        # and `terse`
+        options = (
+            ("--nonaliased", (False, False)),
+            ("nonaliased", (False, False)),
+            ("--terse", (True, True)),
+            ("terse", (True, True)),
+            ("nonaliased terse", (False, True)),
+            ("--nonaliased terse", (False, True)),
+            ("--terse nonaliased", (False, True)),
+        )
+
+        for flags, args in options:
+            with self.subTest(f"{flags}, {args}"):
+                with mock.patch.object(platform, 'platform') as obj:
+                    self.invoke_platform(*shlex.split(flags))
+                    obj.assert_called_once_with(*args)
+
+    def test_help(self):
+        output = io.StringIO()
+
+        with self.assertRaises(SystemExit):
+            with contextlib.redirect_stdout(output):
+                platform._main(args=["--help"])
+
+        self.assertIn("usage:", output.getvalue())
+
+
 if __name__ == '__main__':
     unittest.main()

Misc/NEWS.d/next/Library/2025-03-21-17-34-27.gh-issue-131524.Vj1pO_.rst

@@ -0,0 +1,2 @@
+Add help message to :mod:`platform` command-line interface. Contributed by
+Harry Lees.