Add ability to manually trigger completion menu (#2177)

* Add ability to manually trigger completion menu
* Mention :ALEComplete in completion docs
* Add test for ALEComplete

autoload/ale/completion.vim

@@ -509,6 +509,12 @@ function! ale#completion#GetCompletions() abort
         return
     endif
 
+    call ale#completion#AlwaysGetCompletions()
+endfunction
+
+" This function can be used to manually trigger autocomplete, even when
+" g:ale_completion_enabled is set to false
+function! ale#completion#AlwaysGetCompletions() abort
     let [l:line, l:column] = getcurpos()[1:2]
 
     let l:prefix = ale#completion#GetPrefix(&filetype, l:line, l:column)

doc/ale.txt

@@ -821,6 +821,9 @@ with |g:ale_completion_max_suggestions|.
 If you don't like some of the suggestions you see, you can filter them out
 with |g:ale_completion_excluded_words| or |b:ale_completion_excluded_words|.
 
+The |ALEComplete| command can be used to show completion suggestions manually,
+even when |g:ale_completion_enabled| is set to `0`.
+
                                                 *ale-completion-completopt-bug*
 
 ALE implements completion as you type by temporarily adjusting |completeopt|
@@ -2236,6 +2239,17 @@ ALE will use to search for Python executables.
 ===============================================================================
 8. Commands/Keybinds                                             *ale-commands*
 
+ALEComplete                                                       *ALEComplete*
+
+  Manually trigger LSP autocomplete and show the menu. Works only when called
+  from insert mode. >
+
+    inoremap <silent> <C-Space> <C-\><C-O>:AleComplete<CR>
+<
+  A plug mapping `<Plug>(ale_complete)` is defined for this command. >
+
+    imap <C-Space> <Plug>(ale_complete)
+<
 ALEDocumentation                                             *ALEDocumentation*
 
   Similar to the |ALEHover| command, retrieve documentation information for

plugin/ale.vim

@@ -204,6 +204,8 @@ command! -bar ALEDocumentation :call ale#hover#ShowDocumentationAtCursor()
 " Search for appearances of a symbol, such as a type name or function name.
 command! -nargs=1 ALESymbolSearch :call ale#symbol#Search(<q-args>)
 
+command! -bar ALEComplete :call ale#completion#AlwaysGetCompletions()
+
 " <Plug> mappings for commands
 nnoremap <silent> <Plug>(ale_previous) :ALEPrevious<Return>
 nnoremap <silent> <Plug>(ale_previous_wrap) :ALEPreviousWrap<Return>
@@ -229,6 +231,7 @@ nnoremap <silent> <Plug>(ale_go_to_definition_in_vsplit) :ALEGoToDefinitionInVSp
 nnoremap <silent> <Plug>(ale_find_references) :ALEFindReferences<Return>
 nnoremap <silent> <Plug>(ale_hover) :ALEHover<Return>
 nnoremap <silent> <Plug>(ale_documentation) :ALEDocumentation<Return>
+inoremap <silent> <Plug>(ale_complete) <C-\><C-O>:ALEComplete<Return>
 
 " Set up autocmd groups now.
 call ale#events#Init()

test/test_ale_complete_command.vader

@@ -0,0 +1,22 @@
+Before:
+  function! MockAlwaysGetCompletions() abort
+    let g:get_completions_called = 0
+
+    function! ale#completion#AlwaysGetCompletions() abort
+      let g:get_completions_called = 1
+    endfunction
+  endfunction
+
+  call MockAlwaysGetCompletions()
+
+After:
+  unlet! g:get_completions_called
+  delfunction MockAlwaysGetCompletions
+  delfunction ale#completion#AlwaysGetCompletions
+
+  runtime autoload/ale/completion.vim
+
+Execute(ale#completion#AlwaysGetCompletions should be called when ALEComplete is executed):
+  AssertEqual 0, g:get_completions_called
+  ALEComplete
+  AssertEqual 1, g:get_completions_called