Given foobar (Some imaginary filetype): var y = 3+3; var y = 3 Before: Save g:ale_buffer_info Save g:ale_echo_cursor Save g:ale_run_synchronously Save g:ale_set_highlights Save g:ale_set_loclist Save g:ale_set_quickfix Save g:ale_set_signs Save g:ale_command_wrapper Save g:ale_use_neovim_diagnostics_api let g:ale_command_wrapper = '' let g:ale_buffer_info = {} let g:ale_run_synchronously = 1 unlet! g:ale_run_synchronously_callbacks let g:ale_set_signs = 1 " Disable features we don't need for these tests. let g:ale_set_quickfix = 0 let g:ale_set_loclist = 0 let g:ale_set_highlights = 0 let g:ale_echo_cursor = 0 let g:ale_use_neovim_diagnostics_api = 0 call ale#sign#Clear() function! TestCallback(buffer, output) return [ \ {'lnum': 1, 'text': 'foo', 'type': 'W'}, \ {'lnum': 2, 'text': 'foo', 'type': 'E'}, \] endfunction function! CollectSigns() redir => l:output if has('nvim-0.4.2') || has('patch-8.1.614') silent exec 'sign place group=ale' else silent exec 'sign place' endif redir END let l:actual_sign_list = [] for l:line in split(l:output, "\n") let l:match = matchlist(l:line, ale#sign#ParsePattern()) if len(l:match) > 0 call add(l:actual_sign_list, [l:match[1], l:match[3]]) endif endfor return l:actual_sign_list endfunction call ale#linter#Define('foobar', { \ 'name': 'testlinter', \ 'callback': 'TestCallback', \ 'executable': has('win32') ? 'cmd' : 'echo', \ 'command': has('win32') ? 'echo foo bar' : '/bin/sh -c ''echo foo bar''', \}) After: delfunction TestCallback delfunction CollectSigns unlet! g:ale_run_synchronously_callbacks call ale#sign#Clear() call ale#linter#Reset() Execute(The signs should be updated after linting is done): ALELint call ale#test#FlushJobs() AssertEqual [['1', 'ALEWarningSign'], ['2', 'ALEErrorSign']], CollectSigns() Execute(Signs should not be set when diagnostics API integration is enabled): let g:ale_use_neovim_diagnostics_api = 1 ALELint call ale#test#FlushJobs() AssertEqual [], CollectSigns()