Convert platform CLI to use argparse

Author: Harry-Lees

Lib/platform.py

@@ -1464,9 +1464,24 @@ 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)
-    print(platform(aliased, terse))
-    sys.exit(0)
+def _parse_args(args: list[str] | None):
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument("--terse", action="store_true")
+    parser.add_argument("--nonaliased", action="store_true")
+
+    return parser.parse_args(args)
+
+
+def _main(args: list[str] | None = None):
+    args = _parse_args(args)
+
+    aliased = not args.nonaliased
+
+    print(platform(aliased, args.terse))
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(_main())

Lib/test/test_platform.py

@@ -1,11 +1,15 @@
+import io
+import itertools
 import os
 import copy
+import contextlib
 import pickle
 import platform
 import subprocess
 import sys
 import unittest
 from unittest import mock
+from textwrap import dedent
 
 from test import support
 from test.support import os_helper
@@ -741,5 +745,52 @@ 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):
+        self.invoke_platform("--terse", "--nonaliased")
+        self.invoke_platform("--nonaliased")
+        self.invoke_platform("--terse")
+        self.invoke_platform()
+
+    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()