I use LanguageClient-neovim[0] with pyls[1], tests are run using `:make` which populates the quickfix list with errors. I also heavily use the location list which gets populated with errors and warnings etc. automatically by LanguageClient-neovim. All of this is accessible through convenient keybindings. Full python setup here: https://github.com/L0stLink/anvil
Status bar is lightline[2] with a custom theme, which I haven't gotten around to pushing yet. I can share it if you are interested. Other than the colors on the bar everything should work.
[0] https://github.com/autozimu/LanguageClient-neovim