python · moi90 · Mar 29, 2021 · Mar 29, 2021 · gst · Mar 30, 2021
diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
@@ -19,6 +19,10 @@
 test_frame = namedtuple('frame', ['f_code', 'f_globals', 'f_locals'])
 test_tb = namedtuple('tb', ['tb_frame', 'tb_lineno', 'tb_next'])

+class Unrepresentable:
+    def __repr__(self) -> str:
+        raise Exception("Unrepresentable")
+

 class TracebackCases(unittest.TestCase):
    # For now, a very minimal set of tests.  I want to be sure that
@@ -995,9 +999,9 @@ def test_format_smoke(self):
    def test_locals(self):
        linecache.updatecache('/foo.py', globals())
        c = test_code('/foo.py', 'method')
-        f = test_frame(c, globals(), {'something': 1})
+        f = test_frame(c, globals(), {'something': 1, "unrepresentable": Unrepresentable()})
        s = traceback.StackSummary.extract(iter([(f, 6)]), capture_locals=True)
-        self.assertEqual(s[0].locals, {'something': '1'})
+        self.assertEqual(s[0].locals, {'something': '1', "unrepresentable": "[Unrepresentable: Unrepresentable]"})

    def test_no_locals(self):
        linecache.updatecache('/foo.py', globals())

diff --git a/Lib/traceback.py b/Lib/traceback.py
@@ -223,6 +223,11 @@ def clear_frames(tb):
            pass
        tb = tb.tb_next

+def _try_repr(x):
+    try:
+        return repr(x)
+    except Exception as exc:
+        return "[Unrepresentable: {}]".format(exc)

 class FrameSummary:
    """A single frame from a traceback.
@@ -257,7 +262,7 @@ def __init__(self, filename, lineno, name, *, lookup_line=True,
        self._line = line
        if lookup_line:
            self.line
-        self.locals = {k: repr(v) for k, v in locals.items()} if locals else None
+        self.locals = {k: _try_repr(v) for k, v in locals.items()} if locals else None

    def __eq__(self, other):
        if isinstance(other, FrameSummary):