add a test case for #448

test/autocmd.vim

@@ -0,0 +1,23 @@
+if !has("patch-8.2.0996")
+  finish
+endif
+
+let s:suite = themis#suite('autocmd')
+let s:assert = themis#helper('assert')
+
+function! s:suite.before_each()
+  let g:lightline = {}
+  call lightline#init()
+  tabnew
+  tabonly
+endfunction
+
+function! s:suite.doautoall()
+  tabnew
+  tabnew
+  tabprevious
+  doautoall WinEnter
+  let statusline = getwinvar(1, '&statusline')
+  call s:assert.match(statusline, 'lightline')
+  call s:assert.match(statusline, '_active_')
+endfunction