From 40fae18134916b8499bd992d8bef4ae23bcd2986 Mon Sep 17 00:00:00 2001
From: Sergey Vartanov <me@enzet.ru>
Date: Wed, 9 Jun 2021 00:37:34 +0300
Subject: [PATCH] Possible fix for issue with indentation and fmt: skip (#2281)

Not sure the fix is right.  Here is what I found: issue is connected
with line

    first.prefix = prefix[comment.consumed :]

in `comments.py`.  `first.prefix` is a prefix of the line, that ends
with `# fmt: skip`, but `comment.consumed` is the length of the
`"  # fmt: skip"` string.  If prefix length is greater than 14,
`first.prefix` will grow every time we apply formatting.

Fixes #2254
---
 CHANGES.md             |  1 +
 src/black/comments.py  |  5 ++++-
 tests/data/fmtskip6.py | 13 +++++++++++++
 tests/test_format.py   |  1 +
 4 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 tests/data/fmtskip6.py

diff --git a/CHANGES.md b/CHANGES.md
index 02b3fdf..2d2b3b4 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,7 @@
 
 ### _Black_
 
+- Fix failure caused by `fmt: skip` and indentation (#2281)
 - Account for += assignment when deciding whether to split string (#2312)
 - Correct max string length calculation when there are string operators (#2292)
 - Fixed option usage when using the `--code` flag (#2259)
diff --git a/src/black/comments.py b/src/black/comments.py
index 415e391..c7513c2 100644
--- a/src/black/comments.py
+++ b/src/black/comments.py
@@ -159,7 +159,10 @@ def convert_one_fmt_off_pair(node: Node) -> bool:
             first = ignored_nodes[0]  # Can be a container node with the `leaf`.
             parent = first.parent
             prefix = first.prefix
-            first.prefix = prefix[comment.consumed :]
+            if comment.value in FMT_OFF:
+                first.prefix = prefix[comment.consumed :]
+            if comment.value in FMT_SKIP:
+                first.prefix = ""
             hidden_value = "".join(str(n) for n in ignored_nodes)
             if comment.value in FMT_OFF:
                 hidden_value = comment.value + "\n" + hidden_value
diff --git a/tests/data/fmtskip6.py b/tests/data/fmtskip6.py
new file mode 100644
index 0000000..0a779fc
--- /dev/null
+++ b/tests/data/fmtskip6.py
@@ -0,0 +1,13 @@
+class A:
+    def f(self):
+        for line in range(10):
+            if True:
+                pass  # fmt: skip
+
+# output
+
+class A:
+    def f(self):
+        for line in range(10):
+            if True:
+                pass  # fmt: skip
diff --git a/tests/test_format.py b/tests/test_format.py
index 5c78afe..fc9678a 100644
--- a/tests/test_format.py
+++ b/tests/test_format.py
@@ -41,6 +41,7 @@ SIMPLE_CASES = [
     "fmtskip3",
     "fmtskip4",
     "fmtskip5",
+    "fmtskip6",
     "fstring",
     "function",
     "function2",
-- 
2.39.5