If you're using a plugin manager like vim-plug, the first run of your vimrc may throw errors because alternaut hasn't been installed yet. Any alternaut#RegisterLanguage(...) statements will throw. It's a poor design. I should replace it with a config. Maybe something like this...

let alternaut#conventions = {
\   'javascript': {
\     'file_naming_conventions': ['{name}.test.{ext}'],
\     'directory_naming_conventions': ['__tests__'],
\     'file_extensions': ['js'],
\   },
\ }

I started a new job. Every "component" has a directory and everything related to that component is in that directory, including tests. Here is an example.

src/components/header/
├── styles.js
├── header.js
├── header.test.js
└── package.json

I added '.' to my directory_naming_conventions and continued on with my life. I alternauted from source to test and exclaimed, "NICE! This psycho llama thought of everything!" I toggled from the test to the source and neovim hung indefinitely, until I Ctrl+C-ed.

I might fix it, you might it; we just have to decide first. I consider this a severity-0 bug since it really messes up my flow, man...

I've seen some smart vim people use the <Plug> namespace for plugin mappings. I should use that rather than encouraging people to use internal alternaut functions.

-nnoremap <silent><leader>a <esc>:call alternaut#Toggle()<cr>
+nmap <silent><leader>a <Plug>(alternaut-toggle)