Add test for syntax error (and fix colorization)

Author: pablogsal

Diff for: Lib/test/test_traceback.py

@@ -4284,6 +4284,27 @@ def bar():
         self.assertIn(boldr + ",4)" + reset, lines)
         self.assertIn(red + "bar" + reset + boldr + "()" + reset, lines)
 
+    def test_colorized_syntax_error(self):
+        try:
+            compile("a $ b", "<string>", "exec")
+        except SyntaxError as e:
+            exc = traceback.TracebackException.from_exception(
+                e, capture_locals=True
+            )
+        actual = "".join(exc.format(colorize=True))
+        red = traceback._ANSIColors.RED
+        magenta = traceback._ANSIColors.MAGENTA
+        boldm = traceback._ANSIColors.BOLD_MAGENTA
+        boldr = traceback._ANSIColors.BOLD_RED
+        reset = traceback._ANSIColors.RESET
+        expected = "".join([
+        f'  File {magenta}"<string>"{reset}, line {magenta}1{reset}\n',
+        f'    a {boldr}${reset} b\n',
+        f'      {boldr}^{reset}\n',
+        f'{boldm}SyntaxError{reset}: {magenta}invalid syntax{reset}\n']
+        )
+        self.assertIn(expected, actual)
+
     def test_colorized_traceback_is_the_default(self):
         def foo():
             1/0

Diff for: Lib/traceback.py

@@ -1310,22 +1310,32 @@ def _format_syntax_error(self, stype, **kwargs):
                         # colorize from colno to end_colno
                         ltext = (
                             ltext[:colno] +
-                            _ANSIColors.RED + ltext[colno:end_colno] + _ANSIColors.RESET +
+                            _ANSIColors.BOLD_RED + ltext[colno:end_colno] + _ANSIColors.RESET +
                             ltext[end_colno:]
                         )
-                        start_color = _ANSIColors.RED
+                        start_color = _ANSIColors.BOLD_RED
                         end_color = _ANSIColors.RESET
                     yield '    {}\n'.format(ltext)
-                    yield '    {}{}{}{}'.format(
+                    yield '    {}{}{}{}\n'.format(
                         "".join(caretspace),
                         start_color,
-                        ('^' * (end_colno - colno) + "\n"),
+                        ('^' * (end_colno - colno)),
                         end_color,
                     )
                 else:
                     yield '    {}\n'.format(ltext)
         msg = self.msg or "<no detail available>"
-        yield "{}: {}{}\n".format(stype, msg, filename_suffix)
+        if colorize:
+            yield "{}{}{}: {}{}{}{}\n".format(
+                _ANSIColors.BOLD_MAGENTA,
+                stype,
+                _ANSIColors.RESET,
+                _ANSIColors.MAGENTA,
+                msg,
+                _ANSIColors.RESET,
+                filename_suffix)
+        else:
+            yield "{}: {}{}\n".format(stype, msg, filename_suffix)
 
     def format(self, *, chain=True, _ctx=None, **kwargs):
         """Format the exception.