From f805bc6bfb233d78c4faffe1e262ceb14e2912a3 Mon Sep 17 00:00:00 2001
From: Rio Yu <52408936+rioyu123@users.noreply.github.com>
Date: Sun, 11 Oct 2026 00:28:20 +0800
Subject: [PATCH] fix: preserve memory filesystem entries on same-path rename

---
 pyglove/core/io/file_system.py      |  2 ++
 pyglove/core/io/file_system_test.py | 30 +++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/pyglove/core/io/file_system.py b/pyglove/core/io/file_system.py
index 0cdfee1..e28156c 100644
--- a/pyglove/core/io/file_system.py
+++ b/pyglove/core/io/file_system.py
@@ -447,6 +447,8 @@ def rename(
       raise FileNotFoundError(oldpath_str)
 
     new_entry = self._locate(newpath_str)
+    if new_entry is entry:
+      return
     if new_entry is not None:
       if isinstance(entry, dict):  # oldpath is dir
         if not isinstance(new_entry, dict):
diff --git a/pyglove/core/io/file_system_test.py b/pyglove/core/io/file_system_test.py
index 5ea8d06..217883a 100644
--- a/pyglove/core/io/file_system_test.py
+++ b/pyglove/core/io/file_system_test.py
@@ -378,6 +378,36 @@ def test_rename(self):
     with self.assertRaises(FileNotFoundError):
       fs.rename('/mem/non-existent', '/mem/y')
 
+  def test_rename_same_file(self):
+    fs = file_system.MemoryFileSystem()
+    fs.mkdirs('/mem/a')
+    path = '/mem/a/foo.txt'
+    with fs.open(path, 'w') as f:
+      f.write('foo')
+
+    fs.rename(path, path)
+
+    with fs.open(path) as f:
+      self.assertEqual(f.read(), 'foo')
+
+  def test_rename_same_directory(self):
+    for children in ([], ['b']):
+      with self.subTest(children=children):
+        fs = file_system.MemoryFileSystem()
+        fs.mkdirs('/mem/a')
+        for child in children:
+          fs.mkdir('/mem/a/' + child)
+
+        fs.rename('/mem/a', '/mem/a')
+
+        self.assertTrue(fs.isdir('/mem/a'))
+        self.assertEqual(fs.listdir('/mem/a'), children)
+
+  def test_rename_same_missing_path(self):
+    fs = file_system.MemoryFileSystem()
+    with self.assertRaises(FileNotFoundError):
+      fs.rename('/mem/missing', '/mem/missing')
+
   def test_copy(self):
     fs = file_system.MemoryFileSystem()
     fs.mkdirs('/mem/a')