Diff: new files have extra new line Fixes #945

CHANGELOG.rst

@@ -10,6 +10,7 @@ Release 0.12.0 (unreleased)
 * Fallback and warn if patch is not UTF-8 encoded (#941)
 * Skip patches outside manifest dir (#942)
 * Make patch path in metadata platform independent (#937)
+* Fix extra newlines in patch for new files (#945)
 
 Release 0.11.0 (released 2026-01-03)
 ====================================

dfetch/vcs/patch.py

@@ -82,37 +82,39 @@ def apply_patch(patch_path: str, root: str = ".") -> None:
 
 def create_svn_patch_for_new_file(file_path: str) -> str:
     """Create a svn patch for a new file."""
-    diff = unified_diff_new_file(Path(file_path))
-    return "" if not diff else "\n".join([f"Index: {file_path}", "=" * 67] + diff)
+    diff = _unified_diff_new_file(Path(file_path))
+    return (
+        "" if not diff else "".join([f"Index: {file_path}\n", "=" * 67 + "\n"] + diff)
+    )
 
 
 def create_git_patch_for_new_file(file_path: str) -> str:
     """Create a Git patch for a new untracked file, preserving file mode."""
     path = Path(file_path)
-    diff = unified_diff_new_file(path)
+    diff = _unified_diff_new_file(path)
 
     return (
         ""
         if not diff
-        else "\n".join(
+        else "".join(
             [
-                f"diff --git a/{file_path} b/{file_path}",
-                f"new file mode {_git_mode(path)}",
-                f"index 0000000..{_git_blob_sha1(path)[:7]}",
+                f"diff --git a/{file_path} b/{file_path}\n",
+                f"new file mode {_git_mode(path)}\n",
+                f"index 0000000..{_git_blob_sha1(path)[:7]}\n",
             ]
             + diff
         )
     )
 
 
-def unified_diff_new_file(path: Path) -> list[str]:
+def _unified_diff_new_file(path: Path) -> list[str]:
     """Create a unified diff for a new file."""
     with path.open("r", encoding="utf-8", errors="replace") as new_file:
         lines = new_file.readlines()
 
     return list(
         difflib.unified_diff(
-            [], lines, fromfile="/dev/null", tofile=str(path), lineterm=""
+            [], lines, fromfile="/dev/null", tofile=str(path), lineterm="\n"
         )
     )
 

tests/test_patch.py

@@ -0,0 +1,60 @@
+"""Test the patch module."""
+
+# mypy: ignore-errors
+# flake8: noqa
+
+import pytest
+
+from dfetch.vcs.patch import (
+    create_git_patch_for_new_file,
+    create_svn_patch_for_new_file,
+)
+
+
+def test_create_git_patch_for_new_file(tmp_path):
+    """Check basic patch generation for new files."""
+    test_file = tmp_path / "test.txt"
+    test_file.write_text("Hello World\n\nLine above is empty\n")
+
+    actual_patch = create_git_patch_for_new_file(str(test_file))
+
+    expected_patch = "\n".join(
+        [
+            f"diff --git a/{test_file} b/{test_file}",
+            "new file mode 100644",
+            "index 0000000..8029fa5",
+            "--- /dev/null",
+            f"+++ {test_file}",
+            "@@ -0,0 +1,3 @@",
+            "+Hello World",
+            "+",
+            "+Line above is empty",
+            "",
+        ]
+    )
+
+    assert actual_patch == expected_patch
+
+
+def test_create_svn_patch_for_new_file(tmp_path):
+    """Check basic patch generation for new files."""
+    test_file = tmp_path / "test.txt"
+    test_file.write_text("Hello World\n\nLine above is empty\n")
+
+    actual_patch = create_svn_patch_for_new_file(str(test_file))
+
+    expected_patch = "\n".join(
+        [
+            f"Index: {test_file}",
+            "===================================================================",
+            "--- /dev/null",
+            f"+++ {test_file}",
+            "@@ -0,0 +1,3 @@",
+            "+Hello World",
+            "+",
+            "+Line above is empty",
+            "",
+        ]
+    )
+
+    assert actual_patch == expected_patch