Fix: LF is replaced with CRLF on Windows

bumpversion/cli.py

@@ -197,7 +197,9 @@ def main(original_args=None):
 
         logger.info("Reading config file {}:".format(config_file))
         # TODO: this is a DEBUG level log
-        logger.info(io.open(config_file, "rt", encoding="utf-8").read())
+        with io.open(config_file, "rt", encoding="utf-8") as f:
+            logger.info(f.read())
+            config_new_lines = f.newlines
 
         try:
             # TODO: we're reading the config file twice.
@@ -580,7 +582,7 @@ def main(original_args=None):
         logger.info(new_config.getvalue())
 
         if write_to_config_file:
-            with io.open(config_file, "wt", encoding="utf-8") as f:
+            with io.open(config_file, "wt", encoding="utf-8", newline=config_new_lines) as f:
                 f.write(new_config.getvalue())
 
     except UnicodeEncodeError:

bumpversion/utils.py

@@ -91,6 +91,7 @@ def replace(self, current_version, new_version, context, dry_run):
 
         with io.open(self.path, "rt", encoding="utf-8") as f:
             file_content_before = f.read()
+            file_new_lines = f.newlines
 
         context["current_version"] = self._versionconfig.serialize(
             current_version, context
@@ -135,7 +136,7 @@ def replace(self, current_version, new_version, context, dry_run):
             )
 
         if not dry_run:
-            with io.open(self.path, "wt", encoding="utf-8") as f:
+            with io.open(self.path, "wt", encoding="utf-8", newline=file_new_lines) as f:
                 f.write(file_content_after)
 
     def __str__(self):

tests/test_cli.py

@@ -1916,6 +1916,28 @@ def test_correct_interpolation_for_setup_cfg_files(tmpdir, configfile):
     assert "current_version = 1.0.0" in tmpdir.join(configfile).read()
 
 
+@pytest.mark.parametrize("newline", [b'\n', b'\r\n'])
+def test_retain_newline(tmpdir, configfile, newline):
+    tmpdir.join("file.py").write_binary(dedent("""
+        0.7.2
+        Some Content
+        """).strip().encode(encoding='UTF-8').replace(b'\n', newline))
+    tmpdir.chdir()
+
+    tmpdir.join(configfile).write_binary(dedent("""
+        [bumpversion]
+        current_version = 0.7.2
+        search = {current_version}
+        replace = {new_version}
+        [bumpversion:file:file.py]
+        """).strip().encode(encoding='UTF-8').replace(b'\n', newline))
+
+    main(["major"])
+
+    assert newline in tmpdir.join("file.py").read_binary()
+    assert newline in tmpdir.join(configfile).read_binary()
+
+
 class TestSplitArgsInOptionalAndPositional:
 
     def test_all_optional(self):