Preserve line endings when formatting a file in place (#288)

[etc/vim.git] / tests / test_black.py

diff --git a/tests/test_black.py b/tests/test_black.py
index adf5ede63715fd4d58f0c624eb99385e3db6a5a5..1f93e6afdf7c2172621db8924b24e2d598b11b04 100644 (file)
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -3,7 +3,7 @@ import asyncio
 from concurrent.futures import ThreadPoolExecutor
 from contextlib import contextmanager
 from functools import partial
-from io import StringIO
+from io import BytesIO, TextIOWrapper
 import os
 from pathlib import Path
 import sys
@@ -121,8 +121,9 @@ class BlackTestCase(unittest.TestCase):
         source, expected = read_data("../black")
         hold_stdin, hold_stdout = sys.stdin, sys.stdout
         try:
-            sys.stdin, sys.stdout = StringIO(source), StringIO()
-            sys.stdin.name = "<stdin>"
+            sys.stdin = TextIOWrapper(BytesIO(source.encode("utf8")), encoding="utf8")
+            sys.stdout = TextIOWrapper(BytesIO(), encoding="utf8")
+            sys.stdin.buffer.name = "<stdin>"  # type: ignore
             black.format_stdin_to_stdout(
                 line_length=ll, fast=True, write_back=black.WriteBack.YES
             )
@@ -139,8 +140,9 @@ class BlackTestCase(unittest.TestCase):
         expected, _ = read_data("expression.diff")
         hold_stdin, hold_stdout = sys.stdin, sys.stdout
         try:
-            sys.stdin, sys.stdout = StringIO(source), StringIO()
-            sys.stdin.name = "<stdin>"
+            sys.stdin = TextIOWrapper(BytesIO(source.encode("utf8")), encoding="utf8")
+            sys.stdout = TextIOWrapper(BytesIO(), encoding="utf8")
+            sys.stdin.buffer.name = "<stdin>"  # type: ignore
             black.format_stdin_to_stdout(
                 line_length=ll, fast=True, write_back=black.WriteBack.DIFF
             )
@@ -204,7 +206,7 @@ class BlackTestCase(unittest.TestCase):
         tmp_file = Path(black.dump_to_file(source))
         hold_stdout = sys.stdout
         try:
-            sys.stdout = StringIO()
+            sys.stdout = TextIOWrapper(BytesIO(), encoding="utf8")
             self.assertTrue(ff(tmp_file, write_back=black.WriteBack.DIFF))
             sys.stdout.seek(0)
             actual = sys.stdout.read()
@@ -1108,6 +1110,18 @@ class BlackTestCase(unittest.TestCase):
             result = CliRunner().invoke(black.main, ["-", option, "**()(!!*)"])
             self.assertEqual(result.exit_code, 2)
 
+    def test_preserves_line_endings(self) -> None:
+        with TemporaryDirectory() as workspace:
+            test_file = Path(workspace) / "test.py"
+            for nl in ["\n", "\r\n"]:
+                contents = nl.join(["def f(  ):", "    pass"])
+                test_file.write_bytes(contents.encode())
+                ff(test_file, write_back=black.WriteBack.YES)
+                updated_contents: bytes = test_file.read_bytes()
+                self.assertIn(nl.encode(), updated_contents)  # type: ignore
+                if nl == "\n":
+                    self.assertNotIn(b"\r\n", updated_contents)  # type: ignore
+
 
 if __name__ == "__main__":
     unittest.main()