test: add tests for #14379

test/functional/core/exit_spec.lua

@@ -118,3 +118,31 @@ describe(':cquit', function()
     )
   end)
 end)
+
+describe('no crash after :quit non-last window during exit', function()
+  before_each(function()
+    n.clear()
+  end)
+
+  it('in vim.schedule() callback and when piping to stdin #14379', function()
+    n.fn.system({
+      n.nvim_prog,
+      '-es',
+      '--cmd',
+      "lua vim.schedule(function() vim.cmd('vsplit | quit') end)",
+      '+quit',
+    }, '')
+    eq(0, n.api.nvim_get_vvar('shell_error'))
+  end)
+
+  it('in vim.defer_fn() callback and when piping to stdin #14379', function()
+    n.fn.system({
+      n.nvim_prog,
+      '-es',
+      '--cmd',
+      "lua vim.defer_fn(function() vim.cmd('vsplit | quit') end, 0)",
+      '+quit',
+    }, '')
+    eq(0, n.api.nvim_get_vvar('shell_error'))
+  end)
+end)

test/functional/terminal/tui_spec.lua

@@ -2169,6 +2169,22 @@ describe('TUI', function()
     screen:expect({ any = vim.pesc('[Process exited 1]') })
   end)
 
+  it('exits properly when :quit non-last window in event handler #14379', function()
+    local code = [[
+      vim.defer_fn(function()
+        vim.cmd('vsplit | quit')
+      end, 0)
+      vim.cmd('quit')
+    ]]
+    child_session:notify('nvim_exec_lua', code, {})
+    screen:expect([[
+                                                        |
+      [Process exited 0]^                                |
+                                                        |*4
+      {3:-- TERMINAL --}                                    |
+    ]])
+  end)
+
   it('no stack-use-after-scope with cursor color #22432', function()
     screen:set_option('rgb', true)
     command('set termguicolors')