From b36ba91b7a4d05ee43617383f68cf6ed6fc2f08e Mon Sep 17 00:00:00 2001
From: Steven Arcangeli <stevearc@stevearc.com>
Date: Sun, 5 Mar 2023 23:57:58 -0800
Subject: [PATCH] fix: another case of incorrect alternate buffers (#60)

---
 lua/oil/init.lua      |  1 +
 lua/oil/util.lua      |  5 +++++
 tests/altbuf_spec.lua | 24 ++++++++++++++++++++++++
 3 files changed, 30 insertions(+)

diff --git a/lua/oil/init.lua b/lua/oil/init.lua
index 736ae52..d32ce7d 100644
--- a/lua/oil/init.lua
+++ b/lua/oil/init.lua
@@ -405,6 +405,7 @@ M.select = function(opts)
       vertical = opts.vertical,
       horizontal = opts.horizontal,
       split = opts.split,
+      keepalt = true,
     }
     if vim.tbl_isempty(mods) then
       mods = nil
diff --git a/lua/oil/util.lua b/lua/oil/util.lua
index 156aa5b..d5bef4f 100644
--- a/lua/oil/util.lua
+++ b/lua/oil/util.lua
@@ -102,11 +102,16 @@ M.rename_buffer = function(src_bufnr, dest_buf_name)
   -- rename logic. The only reason we can't use nvim_buf_set_name on files is because vim will
   -- think that the new buffer conflicts with the file next time it tries to save.
   if not vim.loop.fs_stat(dest_buf_name) then
+    local altbuf = vim.fn.bufnr("#")
     -- This will fail if the dest buf name already exists
     local ok = pcall(vim.api.nvim_buf_set_name, src_bufnr, dest_buf_name)
     if ok then
       -- Renaming the buffer creates a new buffer with the old name. Find it and delete it.
       vim.api.nvim_buf_delete(vim.fn.bufadd(bufname), {})
+      if altbuf and vim.api.nvim_buf_is_valid(altbuf) then
+        vim.fn.setreg("#", altbuf)
+      end
+
       return false
     end
   end
diff --git a/tests/altbuf_spec.lua b/tests/altbuf_spec.lua
index 3c0113f..2b74b0a 100644
--- a/tests/altbuf_spec.lua
+++ b/tests/altbuf_spec.lua
@@ -81,6 +81,30 @@ a.describe("Alternate buffer", function()
     assert.equals("bar", vim.fn.expand("#"))
   end)
 
+  a.it("preserves alternate when traversing oil dirs", function()
+    vim.cmd.edit({ args = { "foo" } })
+    oil.open()
+    test_util.wait_for_autocmd("BufReadPost")
+    a.util.sleep(10)
+    assert.equals("foo", vim.fn.expand("#"))
+    vim.api.nvim_win_set_cursor(0, { 1, 1 })
+    oil.select()
+    test_util.wait_for_autocmd("BufReadPost")
+    assert.equals("foo", vim.fn.expand("#"))
+  end)
+
+  a.it("preserves alternate when opening preview", function()
+    vim.cmd.edit({ args = { "foo" } })
+    oil.open()
+    test_util.wait_for_autocmd("BufReadPost")
+    a.util.sleep(10)
+    assert.equals("foo", vim.fn.expand("#"))
+    vim.api.nvim_win_set_cursor(0, { 1, 1 })
+    oil.select({ preview = true })
+    test_util.wait_for_autocmd("BufReadPost")
+    assert.equals("foo", vim.fn.expand("#"))
+  end)
+
   a.describe("floating window", function()
     a.it("sets previous buffer as alternate", function()
       vim.cmd.edit({ args = { "foo" } })