gh-161452: Fix python -m random with a non-positive integer input

Lib/random.py

@@ -1041,18 +1041,24 @@ def _parse_args(arg_list: list[str] | None):
     integer: same as `--integer`
     float: same as `--float`""")
     args = parser.parse_args(arg_list)
-    return args, parser.format_help()
+    return args, parser
+
+
+def _randint_cli(parser, n: int) -> int:
+    if n < 1:
+        parser.error(f"integer must be 1 or greater, got {n}")
+    return randint(1, n)
 
 
 def main(arg_list: list[str] | None = None) -> int | str:
-    args, help_text = _parse_args(arg_list)
+    args, parser = _parse_args(arg_list)
 
     # Explicit arguments
     if args.choice:
         return choice(args.choice)
 
     if args.integer is not None:
-        return randint(1, args.integer)
+        return _randint_cli(parser, args.integer)
 
     if args.float is not None:
         return uniform(0, args.float)
@@ -1067,20 +1073,22 @@ def main(arg_list: list[str] | None = None) -> int | str:
         try:
             # Is it an integer?
             val = int(val)
-            return randint(1, val)
         except ValueError:
             try:
                 # Is it a float?
                 val = float(val)
-                return uniform(0, val)
             except ValueError:
                 # Split in case of space-separated string: "a b c"
                 return choice(val.split())
+            else:
+                return uniform(0, val)
+        else:
+            return _randint_cli(parser, val)
 
     if len(args.input) >= 2:
         return choice(args.input)
 
-    return help_text
+    return parser.format_help()
 
 
 if __name__ == '__main__':

Lib/test/test_random.py

@@ -1443,29 +1443,23 @@ def test_after_fork(self):
 class CommandLineTest(unittest.TestCase):
     @support.force_not_colorized
     def test_parse_args(self):
-        args, help_text = random._parse_args(shlex.split("--choice a b c"))
+        args, parser = random._parse_args(shlex.split("--choice a b c"))
         self.assertEqual(args.choice, ["a", "b", "c"])
-        self.assertStartsWith(help_text, "usage: ")
 
-        args, help_text = random._parse_args(shlex.split("--integer 5"))
+        args, parser = random._parse_args(shlex.split("--integer 5"))
         self.assertEqual(args.integer, 5)
-        self.assertStartsWith(help_text, "usage: ")
 
-        args, help_text = random._parse_args(shlex.split("--float 2.5"))
+        args, parser = random._parse_args(shlex.split("--float 2.5"))
         self.assertEqual(args.float, 2.5)
-        self.assertStartsWith(help_text, "usage: ")
 
-        args, help_text = random._parse_args(shlex.split("a b c"))
+        args, parser = random._parse_args(shlex.split("a b c"))
         self.assertEqual(args.input, ["a", "b", "c"])
-        self.assertStartsWith(help_text, "usage: ")
 
-        args, help_text = random._parse_args(shlex.split("5"))
+        args, parser = random._parse_args(shlex.split("5"))
         self.assertEqual(args.input, ["5"])
-        self.assertStartsWith(help_text, "usage: ")
 
-        args, help_text = random._parse_args(shlex.split("2.5"))
+        args, parser = random._parse_args(shlex.split("2.5"))
         self.assertEqual(args.input, ["2.5"])
-        self.assertStartsWith(help_text, "usage: ")
 
     def test_main(self):
         for command, expected in [
@@ -1482,6 +1476,20 @@ def test_main(self):
             random.seed(0)
             self.assertEqual(random.main(shlex.split(command)), expected)
 
+    @support.force_not_colorized
+    def test_empty_integer_range_error(self):
+        # An integer input is the same as --integer, even when it is
+        # not positive.
+        for value in ["0", "-5"]:
+            err_msg = f"error: integer must be 1 or greater, got {value}\n"
+            for args in [[value], ["--integer", value]]:
+                with self.subTest(args=args):
+                    with (support.captured_stderr() as stderr,
+                          self.assertRaises(SystemExit) as cm):
+                        random.main(args)
+                    self.assertEqual(cm.exception.code, 2)
+                    self.assertEndsWith(stderr.getvalue(), err_msg)
+
 
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Library/2026-11-05-22-26-44.gh-issue-161452.YfFfjq.rst

@@ -0,0 +1,3 @@
+Fix the :mod:`random` :ref:`command-line interface <random-cli>`
+printing a random float for a zero or negative integer input instead of
+failing like ``--integer`` does.