Preserve crlf line endings in blackd (#3257)

Co-authored-by: KotlinIsland <kotlinisland@users.noreply.github.com>

diff --git a/CHANGES.md b/CHANGES.md
index d3ba53fd05fe9a1774a9636f706acc0e351fc48b..4ff181674b16dfc072cabaaced06e9ca97273159 100644 (file)
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -54,7 +54,7 @@
 
 ### _Blackd_
 
-<!-- Changes to blackd -->
+- Windows style (CRLF) newlines will be preserved (#3257).
 
 ### Integrations
 

diff --git a/docs/the_black_code_style/current_style.md b/docs/the_black_code_style/current_style.md
index 3db49e2ba0140fd618f257ff775688f342c3e8e2..59d79c4cd0e50038ccaa3cc747d7fa42e482568a 100644 (file)
--- a/docs/the_black_code_style/current_style.md
+++ b/docs/the_black_code_style/current_style.md
@@ -406,6 +406,11 @@ file that are not enforced yet but might be in a future version of the formatter
 - use variable annotations instead of type comments, even for stubs that target older
   versions of Python.
 
+### Line endings
+
+_Black_ will normalize line endings (`\n` or `\r\n`) based on the first line ending of
+the file.
+
 ## Pragmatism
 
 Early versions of _Black_ used to be absolutist in some respects. They took after its

diff --git a/src/blackd/__init__.py b/src/blackd/__init__.py
index e52a9917cf38a1da2a2cbce68a896f926245f1fe..6bbc7c520866421feefef37befca3e3dd224a11a 100644 (file)
--- a/src/blackd/__init__.py
+++ b/src/blackd/__init__.py
@@ -133,6 +133,13 @@ async def handle(request: web.Request, executor: Executor) -> web.Response:
             executor, partial(black.format_file_contents, req_str, fast=fast, mode=mode)
         )
 
+        # Preserve CRLF line endings
+        if req_str[req_str.find("\n") - 1] == "\r":
+            formatted_str = formatted_str.replace("\n", "\r\n")
+            # If, after swapping line endings, nothing changed, then say so
+            if formatted_str == req_str:
+                raise black.NothingChanged
+
         # Only output the diff in the HTTP response
         only_diff = bool(request.headers.get(DIFF_HEADER, False))
         if only_diff:

diff --git a/tests/test_black.py b/tests/test_black.py
index abd4d00b8e86ab128dcf16e38a8fcfbd054adfb1..96e6f1e6945d8fa1489b244f03fe3436a1522631 100644 (file)
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -1286,6 +1286,17 @@ class BlackTestCase(BlackBaseTestCase):
             if nl == "\n":
                 self.assertNotIn(b"\r\n", output)
 
+    def test_normalize_line_endings(self) -> None:
+        with TemporaryDirectory() as workspace:
+            test_file = Path(workspace) / "test.py"
+            for data, expected in (
+                (b"c\r\nc\n ", b"c\r\nc\r\n"),
+                (b"l\nl\r\n ", b"l\nl\n"),
+            ):
+                test_file.write_bytes(data)
+                ff(test_file, write_back=black.WriteBack.YES)
+                self.assertEqual(test_file.read_bytes(), expected)
+
     def test_assert_equivalent_different_asts(self) -> None:
         with self.assertRaises(AssertionError):
             black.assert_equivalent("{}", "None")

diff --git a/tests/test_blackd.py b/tests/test_blackd.py
index 511bd86441d81aebc9710f8e489d589df772641c..db9a1652f8cb4a38eacb663fb6d8eb4802a87e3d 100644 (file)
--- a/tests/test_blackd.py
+++ b/tests/test_blackd.py
@@ -209,3 +209,20 @@ class BlackDTestCase(AioHTTPTestCase):  # type: ignore[misc]
         response = await self.client.post("/", headers={"Origin": "*"})
         self.assertIsNotNone(response.headers.get("Access-Control-Allow-Origin"))
         self.assertIsNotNone(response.headers.get("Access-Control-Expose-Headers"))
+
+    @unittest_run_loop
+    async def test_preserves_line_endings(self) -> None:
+        for data in (b"c\r\nc\r\n", b"l\nl\n"):
+            # test preserved newlines when reformatted
+            response = await self.client.post("/", data=data + b" ")
+            self.assertEqual(await response.text(), data.decode())
+            # test 204 when no change
+            response = await self.client.post("/", data=data)
+            self.assertEqual(response.status, 204)
+
+    @unittest_run_loop
+    async def test_normalizes_line_endings(self) -> None:
+        for data, expected in ((b"c\r\nc\n", "c\r\nc\r\n"), (b"l\nl\r\n", "l\nl\n")):
+            response = await self.client.post("/", data=data)
+            self.assertEqual(await response.text(), expected)
+            self.assertEqual(response.status, 200)