gh-139374: colorize timeit error traceback

Doc/whatsnew/3.15.rst

@@ -528,6 +528,14 @@ tarfile
   (Contributed by Christoph Walcher in :gh:`57911`.)
 
 
+timeit
+------
+
+* Error tracebacks are now colourised by default. This can be controlled by
+  :ref:`environment variables <using-on-controlling-color>`.
+  (Contributed by Yi Hong in :gh:`139374`.)
+
+
 types
 ------
 

Lib/test/test_timeit.py

@@ -4,7 +4,7 @@
 import io
 from textwrap import dedent
 
-from test.support import captured_stdout
+from test.support import captured_stdout, force_not_colorized
 from test.support import captured_stderr
 
 # timeit's default number of iterations.
@@ -225,6 +225,7 @@ def assert_exc_string(self, exc_string, expected_exc_name):
         self.assertStartsWith(exc_lines[0], 'Traceback')
         self.assertStartsWith(exc_lines[-1], expected_exc_name)
 
+    @force_not_colorized
     def test_print_exc(self):
         s = io.StringIO()
         t = timeit.Timer("1/0")
@@ -351,11 +352,13 @@ def test_main_with_time_unit(self):
         self.assertEqual(error_stringio.getvalue(),
                     "Unrecognized unit. Please select nsec, usec, msec, or sec.\n")
 
+    @force_not_colorized
     def test_main_exception(self):
         with captured_stderr() as error_stringio:
             s = self.run_main(switches=['1/0'])
         self.assert_exc_string(error_stringio.getvalue(), 'ZeroDivisionError')
 
+    @force_not_colorized
     def test_main_exception_fixed_reps(self):
         with captured_stderr() as error_stringio:
             s = self.run_main(switches=['-n1', '1/0'])

Lib/timeit.py

@@ -133,7 +133,7 @@ def __init__(self, stmt="pass", setup="pass", timer=default_timer,
         exec(code, global_ns, local_ns)
         self.inner = local_ns["inner"]
 
-    def print_exc(self, file=None):
+    def print_exc(self, file=None, **kwargs):
         """Helper to print a traceback from the timed code.
 
         Typical use:
@@ -149,16 +149,22 @@ def print_exc(self, file=None):
 
         The optional file argument directs where the traceback is
         sent; it defaults to sys.stderr.
+
+        The optional colorize keyword argument controls whether the
+        traceback is colorized; it defaults to False for programmatic
+        usage. When used from the command line, this is automatically
+        set based on terminal capabilities.
         """
-        import linecache, traceback
+        import linecache, traceback, sys
         if self.src is not None:
             linecache.cache[dummy_src_name] = (len(self.src),
                                                None,
                                                self.src.split("\n"),
                                                dummy_src_name)
         # else the source is already stored somewhere else
 
-        traceback.print_exc(file=file)
+        kwargs['colorize'] = kwargs.get('colorize', False)
+        traceback.print_exc(file=file, **kwargs)
 
     def timeit(self, number=default_number):
         """Time 'number' executions of the main statement.
@@ -260,6 +266,7 @@ def main(args=None, *, _wrap_timer=None):
     if args is None:
         args = sys.argv[1:]
     import getopt
+    import _colorize
     try:
         opts, args = getopt.getopt(args, "n:u:s:r:pvh",
                                    ["number=", "setup=", "repeat=",
@@ -326,7 +333,8 @@ def callback(number, time_taken):
         try:
             number, _ = t.autorange(callback)
         except:
-            t.print_exc()
+            colorize = _colorize.can_colorize()
+            t.print_exc(colorize=colorize)
             return 1
 
         if verbose:
@@ -335,7 +343,8 @@ def callback(number, time_taken):
     try:
         raw_timings = t.repeat(repeat, number)
     except:
-        t.print_exc()
+        colorize = _colorize.can_colorize()
+        t.print_exc(colorize=colorize)
         return 1
 
     def format_time(dt):

Lib/traceback.py

@@ -206,9 +206,9 @@ def _safe_string(value, what, func=str):
 
 # --
 
-def print_exc(limit=None, file=None, chain=True):
+def print_exc(limit=None, file=None, chain=True, **kwargs):
     """Shorthand for 'print_exception(sys.exception(), limit=limit, file=file, chain=chain)'."""
-    print_exception(sys.exception(), limit=limit, file=file, chain=chain)
+    print_exception(sys.exception(), limit=limit, file=file, chain=chain, **kwargs)
 
 def format_exc(limit=None, chain=True):
     """Like print_exc() but return a string."""

Misc/NEWS.d/next/Library/2025-09-27-08-26-31.gh-issue-139374.hfh-dl.rst

@@ -0,0 +1 @@
+:mod:`timeit`: Add color to error tracebacks.