From 6f385b9c254f9f062310055c56dffc030134d8c0 Mon Sep 17 00:00:00 2001
From: Tristan Manchester <tmanchester96@gmail.com>
Date: Fri, 17 Apr 2026 09:39:44 +0200
Subject: [PATCH] Use full lines for Python relative import moves

---
 desloppify/languages/python/move.py           | 30 +++++++++++----
 .../languages/python/tests/test_py_move.py    | 38 +++++++++++++++++++
 2 files changed, 61 insertions(+), 7 deletions(-)

diff --git a/desloppify/languages/python/move.py b/desloppify/languages/python/move.py
index df250fe64..7bcb182b0 100644
--- a/desloppify/languages/python/move.py
+++ b/desloppify/languages/python/move.py
@@ -49,6 +49,19 @@ def _replace_exact_module(line: str, old_module: str, new_module: str) -> str:
     return re.sub(rf"(?<!\w){re.escape(old_module)}(?![\w.])", new_module, line)
 
 
+def _replace_relative_from_module(
+    line: str,
+    old_module: str,
+    new_module: str,
+) -> str:
+    """Replace the module portion of a relative ``from`` import line."""
+    return re.sub(
+        rf"^from\s+{re.escape(old_module)}(?=\s+import\b)",
+        f"from {new_module}",
+        line,
+    )
+
+
 def _resolve_py_relative(source_dir: Path, dots: str, remainder: str) -> str | None:
     """Resolve a relative Python import to an absolute file path."""
     dot_count = len(dots)
@@ -154,9 +167,11 @@ def find_replacements(
                 if resolved and str(Path(resolved).resolve()) == source_abs:
                     new_rel = _compute_py_relative_import(importer, dest_abs)
                     if new_rel:
-                        old_from = f"from {dots}{remainder}"
-                        new_from = f"from {new_rel}"
-                        replacements.append((old_from, new_from))
+                        new_line = _replace_relative_from_module(
+                            stripped, f"{dots}{remainder}", new_rel
+                        )
+                        if new_line != stripped:
+                            replacements.append((stripped, new_line))
 
         if replacements:
             changes[importer] = _dedup(replacements)
@@ -199,10 +214,11 @@ def find_self_replacements(
         if not new_rel:
             continue
 
-        old_from = f"from {dots}{remainder}"
-        new_from = f"from {new_rel}"
-        if old_from != new_from:
-            replacements.append((old_from, new_from))
+        new_line = _replace_relative_from_module(
+            stripped, f"{dots}{remainder}", new_rel
+        )
+        if new_line != stripped:
+            replacements.append((stripped, new_line))
 
     return _dedup(replacements)
 
diff --git a/desloppify/languages/python/tests/test_py_move.py b/desloppify/languages/python/tests/test_py_move.py
index 749a751f9..d520184ea 100644
--- a/desloppify/languages/python/tests/test_py_move.py
+++ b/desloppify/languages/python/tests/test_py_move.py
@@ -5,6 +5,7 @@
 from pathlib import Path
 
 import desloppify.languages.python.move as py_move
+from desloppify.languages.python.detectors.deps import build_dep_graph
 
 
 def test_move_py_module_imports():
@@ -70,3 +71,40 @@ def test_resolve_py_relative_package(self, tmp_path):
     def test_resolve_py_relative_not_found(self, tmp_path):
         result = py_move._resolve_py_relative(tmp_path, ".", "nonexistent")
         assert result is None
+
+    def test_relative_import_replacement_uses_full_line(self, tmp_path, monkeypatch):
+        pkg_dir = tmp_path / "pkg"
+        pkg_dir.mkdir()
+        (pkg_dir / "__init__.py").write_text("SOME_CONSTANT = 42\n")
+        (pkg_dir / "utils.py").write_text("def helper():\n    return 1\n")
+
+        sub_dir = pkg_dir / "sub"
+        sub_dir.mkdir()
+        importer = sub_dir / "importer.py"
+        importer.write_text(
+            "from .. import SOME_CONSTANT\nfrom ..utils import helper\n"
+        )
+
+        monkeypatch.setenv("DESLOPPIFY_ROOT", str(tmp_path))
+
+        graph = build_dep_graph(tmp_path)
+        source_abs = str((pkg_dir / "__init__.py").resolve())
+        dest_abs = str((tmp_path / "newpkg" / "__init__.py").resolve())
+
+        changes = py_move.find_replacements(source_abs, dest_abs, graph)
+        importer_abs = str(importer.resolve())
+
+        assert changes[importer_abs] == [
+            (
+                "from .. import SOME_CONSTANT",
+                "from ...newpkg import SOME_CONSTANT",
+            )
+        ]
+
+        content = importer.read_text()
+        for old_str, new_str in changes[importer_abs]:
+            content = content.replace(old_str, new_str)
+
+        assert content == (
+            "from ...newpkg import SOME_CONSTANT\nfrom ..utils import helper\n"
+        )