Address additional cases

Author: savannahostrowski

Lib/argparse.py

@@ -691,26 +691,38 @@ def _expand_help(self, action):
 
         t = self._theme
 
+        result = help_string % params
+
         if not t.reset:
-            return help_string % params
+            return result
+
+        # Match format specifiers like: %s, %d, %(key)s, etc.
+        fmt_spec = r'''
+            %
+            (?:
+                %                           # %% escape
+                |
+                (?:\((?P<key>[^)]*)\))?     # key
+                [-#0\ +]*                   # flags
+                (?:\*|\d+)?                 # width
+                (?:\.(?:\*|\d+))?           # precision
+                [hlL]?                      # length modifier
+                [diouxXeEfFgGcrsa]          # conversion type
+            )
+        '''
 
-        # Format first to preserve types for specifiers, like %x that require int.
         def colorize(match):
-            spec, name = match.group(0, 1)
+            spec, key = match.group(0, 'key')
             if spec == '%%':
                 return '%'
-            if name in params:
-                formatted = spec % {name: params[name]}
+            if key is not None:
+                # %(key)... - format and colorize
+                formatted = spec % {key: params[key]}
                 return f'{t.interpolated_value}{formatted}{t.reset}'
-            return spec
+            # bare %s etc. - format with full params dict, no colorization
+            return spec % params
 
-        # Match %% or %(name)... format specifiers
-        result = _re.sub(r'%%|%\((\w+)\)[^a-z]*[a-z]', colorize,
-                         help_string, flags=_re.IGNORECASE)
-
-        if '%' in result:
-            raise ValueError(f"invalid format specifier in: {help_string!r}")
-        return result
+        return _re.sub(fmt_spec, colorize, help_string, flags=_re.VERBOSE)
 
     def _iter_indented_subactions(self, action):
         try:

Lib/test/test_argparse.py

@@ -7667,17 +7667,33 @@ def test_help_with_format_specifiers(self):
         # GH-142950: format specifiers like %x should work with color=True
         parser = argparse.ArgumentParser(prog='PROG', color=True)
         parser.add_argument('--hex', type=int, default=255,
-                            help='hex: %(default)x')
+                            help='hex: %(default)x, alt: %(default)#x')
+        parser.add_argument('--zero', type=int, default=7,
+                            help='zero: %(default)05d')
         parser.add_argument('--str', default='test',
                             help='str: %(default)s')
+        parser.add_argument('--pct', type=int, default=50,
+                            help='pct: %(default)d%%')
+        parser.add_argument('--literal', help='literal: 100%%')
+        parser.add_argument('--prog', help='prog: %(prog)s')
+        parser.add_argument('--type', type=int, help='type: %(type)s')
+        parser.add_argument('--choices', choices=['a', 'b'],
+                            help='choices: %(choices)s')
 
         help_text = parser.format_help()
 
         interp = self.theme.interpolated_value
         reset = self.theme.reset
 
         self.assertIn(f'hex: {interp}ff{reset}', help_text)
+        self.assertIn(f'alt: {interp}0xff{reset}', help_text)
+        self.assertIn(f'zero: {interp}00007{reset}', help_text)
         self.assertIn(f'str: {interp}test{reset}', help_text)
+        self.assertIn(f'pct: {interp}50{reset}%', help_text)
+        self.assertIn('literal: 100%', help_text)
+        self.assertIn(f'prog: {interp}PROG{reset}', help_text)
+        self.assertIn(f'type: {interp}int{reset}', help_text)
+        self.assertIn(f'choices: {interp}a, b{reset}', help_text)
 
     def test_print_help_uses_target_file_for_color_decision(self):
         parser = argparse.ArgumentParser(prog='PROG', color=True)