From c712d57ca9e30ba0db61c2fd7e4a2bf67f58bcc2 Mon Sep 17 00:00:00 2001
From: Shantanu <12621235+hauntsaninja@users.noreply.github.com>
Date: Fri, 27 Oct 2023 12:17:54 -0700
Subject: [PATCH] Add trailing comma test case for hugging parens (#3991)

---
 docs/the_black_code_style/future_style.md        | 13 +++++++++++++
 ...hug_parens_with_braces_and_square_brackets.py | 16 ++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/docs/the_black_code_style/future_style.md b/docs/the_black_code_style/future_style.md
index f2534b0f0d0..c744902577d 100644
--- a/docs/the_black_code_style/future_style.md
+++ b/docs/the_black_code_style/future_style.md
@@ -139,6 +139,19 @@ foo([
 ])
 ```
 
+You can use a magic trailing comma to avoid this compacting behavior; by default,
+_Black_ will not reformat the following code:
+
+```python
+foo(
+    [
+        1,
+        2,
+        3,
+    ],
+)
+```
+
 ### Improved multiline string handling
 
 _Black_ is smarter when formatting multiline strings, especially in function arguments,
diff --git a/tests/data/cases/preview_hug_parens_with_braces_and_square_brackets.py b/tests/data/cases/preview_hug_parens_with_braces_and_square_brackets.py
index 98ed342fcbc..6d10518133c 100644
--- a/tests/data/cases/preview_hug_parens_with_braces_and_square_brackets.py
+++ b/tests/data/cases/preview_hug_parens_with_braces_and_square_brackets.py
@@ -36,6 +36,14 @@ def foo_square_brackets(request):
     ]
 )
 
+func(
+    [
+        'a',
+        'b',
+        'c',
+    ],
+)
+
 func(  # a
     [  # b
         "c",  # c
@@ -171,6 +179,14 @@ def foo_square_brackets(request):
     "c",
 ])
 
+func(
+    [
+        "a",
+        "b",
+        "c",
+    ],
+)
+
 func([  # a  # b
     "c",  # c
     "d",  # d