From cf8e998f46e89da39fa64029cc4550e2862f7ec2 Mon Sep 17 00:00:00 2001
From: =?utf8?q?=C5=81ukasz=20Langa?= <lukasz@langa.pl>
Date: Wed, 11 Apr 2018 16:25:47 -0700
Subject: [PATCH 1/1] Don't omit escaping the second consecutive quote

This would produce invalid code for strings like `"x = ''; y = \"\""`.
---
 black.py               |  3 +++
 tests/string_quotes.py | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/black.py b/black.py
index c7cfa2f..9581d63 100644
--- a/black.py
+++ b/black.py
@@ -1998,6 +1998,9 @@ def normalize_string_quotes(leaf: Leaf) -> None:
     else:
         new_body = escaped_orig_quote.sub(rf"\1{orig_quote}", body)
         new_body = unescaped_new_quote.sub(rf"\1\\{new_quote}", new_body)
+        # Add escapes again for consecutive occurences of new_quote (sub
+        # doesn't match overlapping substrings).
+        new_body = unescaped_new_quote.sub(rf"\1\\{new_quote}", new_body)
     if new_quote == '"""' and new_body[-1] == '"':
         # edge case:
         new_body = new_body[:-1] + '\\"'
diff --git a/tests/string_quotes.py b/tests/string_quotes.py
index 1532a7a..8ccd041 100644
--- a/tests/string_quotes.py
+++ b/tests/string_quotes.py
@@ -30,6 +30,14 @@ jumps over\n\
 the \'lazy\' dog.\n\
 '
 re.compile(r'[\\"]')
+"x = ''; y = \"\""
+"x = '''; y = \"\""
+"x = ''''; y = \"\""
+"x = '' ''; y = \"\""
+"x = ''; y = \"\"\""
+"x = '''; y = \"\"\"\""
+"x = ''''; y = \"\"\"\"\""
+"x = '' ''; y = \"\"\"\"\""
 
 # output
 
@@ -65,3 +73,11 @@ jumps over\n\
 the 'lazy' dog.\n\
 "
 re.compile(r'[\\"]')
+"x = ''; y = \"\""
+"x = '''; y = \"\""
+"x = ''''; y = \"\""
+"x = '' ''; y = \"\""
+'x = \'\'; y = """'
+'x = \'\'\'; y = """"'
+'x = \'\'\'\'; y = """""'
+'x = \'\' \'\'; y = """""'
-- 
2.39.5