From ab0895c454eebf3a03099eba9239b64664e196e0 Mon Sep 17 00:00:00 2001
From: Yilei Yang <yileiyang@google.com>
Date: Fri, 30 Sep 2022 12:25:21 -0700
Subject: [PATCH] Fix a bug where empty line is added before eof.

---
 src/black/__init__.py                                         | 2 ++
 .../simple_cases/docstring_no_extra_empty_line_before_eof.py  | 4 ++++
 2 files changed, 6 insertions(+)
 create mode 100644 tests/data/simple_cases/docstring_no_extra_empty_line_before_eof.py

diff --git a/src/black/__init__.py b/src/black/__init__.py
index 42b56a52d2b..0dd2ec385b7 100644
--- a/src/black/__init__.py
+++ b/src/black/__init__.py
@@ -1085,6 +1085,8 @@ def _format_str_once(src_contents: str, *, mode: Mode) -> str:
             current_line, mode=mode, features=split_line_features
         ):
             block.content_lines.append(str(line))
+    if dst_blocks:
+        dst_blocks[-1].after = 0
     dst_contents = []
     for block in dst_blocks:
         dst_contents.extend(block.all_lines())
diff --git a/tests/data/simple_cases/docstring_no_extra_empty_line_before_eof.py b/tests/data/simple_cases/docstring_no_extra_empty_line_before_eof.py
new file mode 100644
index 00000000000..6fea860adf6
--- /dev/null
+++ b/tests/data/simple_cases/docstring_no_extra_empty_line_before_eof.py
@@ -0,0 +1,4 @@
+# Make sure when the file ends with class's docstring,
+# It doesn't add extra blank lines.
+class ClassWithDocstring:
+    """A docstring."""