2 files changed, 55 insertions, 1 deletions
diff --git a/test/functional/ui/embed_spec.lua b/test/functional/ui/embed_spec.lua
index e655ee1b54..f6bdd2215d 100644
--- a/test/functional/ui/embed_spec.lua
+++ b/test/functional/ui/embed_spec.lua
@@ -171,6 +171,56 @@ describe('--embed UI', function()
     }
     eq({ [16711935] = true }, seen) -- we only saw the last one, despite 16777215 was set internally earlier
   end)
+
+  it('updates cwd of attached UI #21771', function()
+    clear { args_rm = { '--headless' } }
+
+    local screen = Screen.new(40, 8)
+    screen:attach()
+
+    screen:expect {
+      condition = function()
+        eq(helpers.paths.test_source_path, screen.pwd)
+      end,
+    }
+
+    -- Change global cwd
+    helpers.command(string.format('cd %s/src/nvim', helpers.paths.test_source_path))
+
+    screen:expect {
+      condition = function()
+        eq(string.format('%s/src/nvim', helpers.paths.test_source_path), screen.pwd)
+      end,
+    }
+
+    -- Split the window and change the cwd in the split
+    helpers.command('new')
+    helpers.command(string.format('lcd %s/test', helpers.paths.test_source_path))
+
+    screen:expect {
+      condition = function()
+        eq(string.format('%s/test', helpers.paths.test_source_path), screen.pwd)
+      end,
+    }
+
+    -- Move to the original window
+    helpers.command('wincmd p')
+
+    screen:expect {
+      condition = function()
+        eq(string.format('%s/src/nvim', helpers.paths.test_source_path), screen.pwd)
+      end,
+    }
+
+    -- Change global cwd again
+    helpers.command(string.format('cd %s', helpers.paths.test_source_path))
+
+    screen:expect {
+      condition = function()
+        eq(helpers.paths.test_source_path, screen.pwd)
+      end,
+    }
+  end)
 end)
 
 describe('--embed --listen UI', function()
diff --git a/test/functional/ui/screen.lua b/test/functional/ui/screen.lua
index 644ee910b6..07333f2e21 100644
--- a/test/functional/ui/screen.lua
+++ b/test/functional/ui/screen.lua
@@ -140,6 +140,7 @@ function Screen.new(width, height)
     suspended = false,
     mode = 'normal',
     options = {},
+    pwd = '',
     popupmenu = nil,
     cmdline = {},
     cmdline_block = {},
@@ -212,7 +213,6 @@ function Screen:attach(options, session)
   if options.ext_linegrid == nil then
     options.ext_linegrid = true
   end
-
   self._session = session
   self._options = options
   self._clear_attrs = (not options.ext_linegrid) and {} or nil
@@ -1108,6 +1108,10 @@ function Screen:_handle_option_set(name, value)
   self.options[name] = value
 end
 
+function Screen:_handle_chdir(path)
+  self.pwd = vim.fs.normalize(path, { expand_env = false })
+end
+
 function Screen:_handle_popupmenu_show(items, selected, row, col, grid)
   self.popupmenu = { items = items, pos = selected, anchor = { grid, row, col } }
 end