fix handling of empty triple quoted strings (#314)

diff --git a/README.md b/README.md
index 411c9bf6cf3bed57296aa51a7af1edb2379bdcd1..580607fb148b15aa291f9f2476b8b00b11f53822 100644 (file)
--- a/README.md
+++ b/README.md
@@ -813,6 +813,7 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 
 * fixed improper unmodified file caching when `-S` was used
 
+* fixed formatting of empty triple quoted strings (#313)
 
 ### 18.6b1
 

diff --git a/black.py b/black.py
index dd7fe3911e630990cbbd547ee156ff830a37be4e..1d2f1a304ee768bac626d50e8fef60721e868b34 100644 (file)
--- a/black.py
+++ b/black.py
@@ -2546,7 +2546,7 @@ def normalize_string_quotes(leaf: Leaf) -> None:
             leaf.value = f"{prefix}{orig_quote}{body}{orig_quote}"
         new_body = sub_twice(escaped_orig_quote, rf"\1\2{orig_quote}", new_body)
         new_body = sub_twice(unescaped_new_quote, rf"\1\\{new_quote}", new_body)
-    if new_quote == '"""' and new_body[-1] == '"':
+    if new_quote == '"""' and new_body[-1:] == '"':
         # edge case:
         new_body = new_body[:-1] + '\\"'
     orig_escape_count = body.count("\\")

diff --git a/tests/data/string_quotes.py b/tests/data/string_quotes.py
index 1ac6b06a56e4249b79c00c98a7e060a6f08bafb9..807f8669f5a647b9cbf2535aa0e844d7115a8858 100644 (file)
--- a/tests/data/string_quotes.py
+++ b/tests/data/string_quotes.py
@@ -1,3 +1,4 @@
+''''''
 '\''
 '"'
 "'"
@@ -45,6 +46,7 @@ re.compile(r'[\\"]')
 
 # output
 
+""""""
 "'"
 '"'
 "'"