gh-133049: Require an input file in pygettext

Like xgettext, exit with status 1 and an error message when no input file is given, instead of writing a header-only messages.pot. The check runs before the arguments are expanded, so a path that matches nothing keeps its current behaviour.

Author: RajaBabu15

Lib/test/test_tools/test_i18n.py

@@ -7,7 +7,9 @@
 from textwrap import dedent
 from pathlib import Path
 
-from test.support.script_helper import assert_python_ok
+from test.support.script_helper import (assert_python_failure,
+                                        assert_python_ok,
+                                        run_python_until_end)
 from test.test_tools import imports_under_tool, skip_if_missing, toolsdir
 from test.support.os_helper import temp_cwd, temp_dir
 
@@ -122,7 +124,8 @@ def test_header(self):
            http://www.gnu.org/software/gettext/manual/gettext.html#Header-Entry
         """
         with temp_cwd(None) as cwd:
-            assert_python_ok('-Xutf8', self.script)
+            Path('test.py').touch()
+            assert_python_ok('-Xutf8', self.script, 'test.py')
             with open('messages.pot', encoding='utf-8') as fp:
                 data = fp.read()
             header = self.get_header(data)
@@ -149,7 +152,8 @@ def test_POT_Creation_Date(self):
         """ Match the date format from xgettext for POT-Creation-Date """
         from datetime import datetime
         with temp_cwd(None) as cwd:
-            assert_python_ok('-Xutf8', self.script)
+            Path('test.py').touch()
+            assert_python_ok('-Xutf8', self.script, 'test.py')
             with open('messages.pot', encoding='utf-8') as fp:
                 data = fp.read()
             header = self.get_header(data)
@@ -165,11 +169,28 @@ def test_POT_Creation_Date(self):
     def test_output_option(self):
         for opt in ('-o', '--output='):
             with temp_cwd():
-                assert_python_ok(self.script, f'{opt}test')
+                Path('test.py').touch()
+                assert_python_ok(self.script, f'{opt}test', 'test.py')
                 self.assertTrue(os.path.exists('test'))
-                res = assert_python_ok(self.script, f'{opt}-')
+                res = assert_python_ok(self.script, f'{opt}-', 'test.py')
                 self.assertIn(b'Project-Id-Version: PACKAGE VERSION', res.out)
 
+    def test_no_input_file(self):
+        """Like xgettext, require at least one input file."""
+        for args in ((), ('-o', '-')):
+            with self.subTest(args=args), temp_cwd(None):
+                res = assert_python_failure('-Xutf8', self.script, *args)
+                self.assertEqual(res.rc, 1)
+                self.assertEqual(res.out, b'')
+                self.assertIn(b'pygettext: no input file given', res.err)
+                self.assertFalse(os.path.exists('messages.pot'))
+
+    def test_missing_input_file_is_not_no_input(self):
+        # A path that matches nothing is not the same as no path at all.
+        with temp_cwd(None):
+            res, _ = run_python_until_end(self.script, 'does_not_exist.py')
+            self.assertNotIn(b'no input file given', res.err)
+
     def test_funcdocstring(self):
         for doc in ('"""doc"""', "r'''doc'''", "R'doc'", 'u"doc"'):
             with self.subTest(doc):

Misc/NEWS.d/next/Tools-Demos/2026-10-27-18-07-31.gh-issue-133049.ESXpEi.rst

@@ -0,0 +1,2 @@
+:program:`pygettext` now exits with an error if no input file is given,
+like :program:`xgettext`.

Tools/i18n/pygettext.py

@@ -817,6 +817,13 @@ class Options:
     else:
         options.toexclude = []
 
+    # xgettext requires at least one input file
+    if not args:
+        print("pygettext: no input file given\n"
+              "Try 'pygettext --help' for more information.",
+              file=sys.stderr)
+        sys.exit(1)
+
     # resolve args to module lists
     expanded = []
     for arg in args: