From cab20c74a17d35876a13ee0cae4700c9f9c84a98 Mon Sep 17 00:00:00 2001
From: David Nies <david.nies@posteo.de>
Date: Thu, 14 Nov 2024 00:09:04 +0100
Subject: [PATCH] Make sure locals_max_{length,string} work as expected in case
 they are None

---
 src/structlog/tracebacks.py |  4 ++--
 tests/test_tracebacks.py    | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/src/structlog/tracebacks.py b/src/structlog/tracebacks.py
index 2392b342..8fada4da 100644
--- a/src/structlog/tracebacks.py
+++ b/src/structlog/tracebacks.py
@@ -382,10 +382,10 @@ def __init__(
         max_frames: int = MAX_FRAMES,
         use_rich: bool = True,
     ) -> None:
-        if locals_max_length < 0:
+        if locals_max_length is not None and locals_max_length < 0:
             msg = f'"locals_max_length" must be >= 0: {locals_max_length}'
             raise ValueError(msg)
-        if locals_max_string < 0:
+        if locals_max_string is not None and locals_max_string < 0:
             msg = f'"locals_max_string" must be >= 0: {locals_max_string}'
             raise ValueError(msg)
         if max_frames < 2:
diff --git a/tests/test_tracebacks.py b/tests/test_tracebacks.py
index a086a042..273bc475 100644
--- a/tests/test_tracebacks.py
+++ b/tests/test_tracebacks.py
@@ -531,6 +531,40 @@ def bar(n):
     ]
 
 
+@pytest.mark.parametrize(
+    ("kwargs", "local_variable"),
+    [
+        (
+            {"locals_max_string": None},
+            "x" * (tracebacks.LOCALS_MAX_STRING + 10),
+        ),
+        (
+            {"locals_max_length": None},
+            list(range(tracebacks.LOCALS_MAX_LENGTH + 10)),
+        ),
+    ],
+)
+def test_exception_dict_transformer_locals_max_accept_none_argument(
+    kwargs, local_variable
+):
+    try:
+        my_local = local_variable
+        1 / 0
+    except Exception as e:
+        format_json = tracebacks.ExceptionDictTransformer(
+            show_locals=True, **kwargs
+        )
+        result = format_json((type(e), e, e.__traceback__))
+
+    _ = my_local
+
+    assert len(result) == 1
+    assert len(result[0]["frames"]) == 1
+
+    frame = result[0]["frames"][0]
+    assert frame["locals"]["my_local"].strip("'") == str(local_variable)
+
+
 def test_json_traceback():
     """
     Tracebacks are formatted to JSON with all information.