From 44eae48b7566c161d2e0cd1b09151591c27a64ef Mon Sep 17 00:00:00 2001
From: zeertzjq <zeertzjq@outlook.com>
Date: Fri, 2 Jan 2026 07:05:48 +0800
Subject: [PATCH] vim-patch:9.1.0893: No test that undofile format does not
 regress (#37193)

Problem:  No test that undofile format does not regress
Solution: include a sample undofile to make sure we are always able to
          read it

This is so, that we don't unintentionally change the undofile format and
make sure we can load an undo file that has been created by an older
Vim.

closes: vim/vim#16127

https://github.com/vim/vim/commit/14382c8bc96cc8f3985a01ab58c2f4d7b4d9ec85

Convert the undo file in samples/ using method from #13973.

Co-authored-by: Christian Brabandt <cb@256bit.org>
(cherry picked from commit 94f7302e66965374c5b60f54c5e4b4f40b5a9c53)
---
 test/old/testdir/samples/test_undo.txt      |   3 ++
 test/old/testdir/samples/test_undo.txt.undo | Bin 0 -> 1411 bytes
 test/old/testdir/test_undo.vim              |  29 ++++++++++++++++++++
 3 files changed, 32 insertions(+)
 create mode 100644 test/old/testdir/samples/test_undo.txt
 create mode 100644 test/old/testdir/samples/test_undo.txt.undo

diff --git a/test/old/testdir/samples/test_undo.txt b/test/old/testdir/samples/test_undo.txt
new file mode 100644
index 0000000000..4cb29ea38f
--- /dev/null
+++ b/test/old/testdir/samples/test_undo.txt
@@ -0,0 +1,3 @@
+one
+two
+three
diff --git a/test/old/testdir/samples/test_undo.txt.undo b/test/old/testdir/samples/test_undo.txt.undo
new file mode 100644
index 0000000000000000000000000000000000000000..cc3d3dd7c38e37133e84b77e5c038558aade686c
GIT binary patch
literal 1411
zcmWH`%$*;a=aT=FfqB=|`5TvYc)h&J<n=e>qP6_G<H-lt9GidPVX9L=-sg*t7#J9s
z86W^gGop!s#6g%L-My2Y1tiPJ5Pt!phk*%7gD8j;h{eFb@c;k+|8S$BVxtr_Lm=I~
zlLZ_d3=Cf-&<qAe1%qj$X(KqIKs;~^LREnx4I~DlArS@QK_y2iYKK6&dnYS$L?H(@
zm<^6TFbifiJnFzv1QUg3Opq7|k47C*z|e-7?%v4;jygt29s>tE)GBa<fujyt6rAgx
GuL1zqus0U~

literal 0
HcmV?d00001

diff --git a/test/old/testdir/test_undo.vim b/test/old/testdir/test_undo.vim
index d876277850..b008c9216c 100644
--- a/test/old/testdir/test_undo.vim
+++ b/test/old/testdir/test_undo.vim
@@ -883,4 +883,33 @@ func Test_undo_range_normal()
   bwipe!
 endfunc
 
+func Test_load_existing_undofile()
+  CheckFeature persistent_undo
+  sp samples/test_undo.txt
+  let mess=execute(':verbose rundo samples/test_undo.txt.undo')
+  call assert_match('Finished reading undo file', mess)
+
+  call assert_equal(['one', 'two', 'three'], getline(1, '$'))
+  norm! u
+  call assert_equal(['one', 'two'], getline(1, '$'))
+  norm! u
+  call assert_equal(['one'], getline(1, '$'))
+  norm! u
+  call assert_equal([''], getline(1, '$'))
+  let mess = execute(':norm! u')
+  call assert_equal([''], getline(1, '$'))
+  call assert_match('Already at oldest change', mess)
+  exe ":norm! \<c-r>"
+  call assert_equal(['one'], getline(1, '$'))
+  exe ":norm! \<c-r>"
+  call assert_equal(['one', 'two'], getline(1, '$'))
+  exe ":norm! \<c-r>"
+  call assert_equal(['one', 'two', 'three'], getline(1, '$'))
+  let mess = execute(":norm! \<c-r>")
+  call assert_equal(['one', 'two', 'three'], getline(1, '$'))
+  call assert_match('Already at newest change', mess)
+  bw!
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab