gh-95395: Add argument type error test (GH-95412) (GH-95745)

(cherry picked from commit 4703c15)

Co-authored-by: Sion Kang <[email protected]>

Author: miss-islington

Lib/test/test_grp.py

@@ -49,10 +49,12 @@ def test_values_extended(self):
 
     def test_errors(self):
         self.assertRaises(TypeError, grp.getgrgid)
+        self.assertRaises(TypeError, grp.getgrgid, 3.14)
         self.assertRaises(TypeError, grp.getgrnam)
+        self.assertRaises(TypeError, grp.getgrnam, 42)
         self.assertRaises(TypeError, grp.getgrall, 42)
         # embedded null character
-        self.assertRaises(ValueError, grp.getgrnam, 'a\x00b')
+        self.assertRaisesRegex(ValueError, 'null', grp.getgrnam, 'a\x00b')
 
         # try to get some errors
         bynames = {}