doc: follow up on #141: VADER_OUTPUT_FILE

[blueyed]

No description provided.

[rdnetto]

Nit: VADER_OUTPUT_FILE=/dev/stderr doesn't actually work with Neovim - you need to write it to a file and then cat it afterwards. It might be simpler to just say it's useful with Neovim because the test results are not logged to the terminal by default.

[blueyed]

OK, will improve it more.
However, I am using this with Neovim.

How do you run Vader with Neovim?

[rdnetto]

env VADER_OUTPUT_FILE=/dev/stderr nvim -N -u vimrc.vim -c 'Vader! **/*.vader'                                                                                                           

Doesn't work for me, where vimrc.vim is a minimal vimrc used in CI.

[blueyed]

Neovim needs the --headless option additionally, or stdout needs to be redirected (so that it's not a TTY).

With Neomake I am using basically this: VADER_OUTPUT_FILE=/dev/stderr nvim --headless -Nu vimrc -c 'Vader! *' 2>&1 </dev/null >/dev/null.

It works on Travis for Vader itself without any special handling (except for setting VADER_OUTPUT_FILE), likely because it's not a tty altogether there.

Ref: neovim/neovim#4772

[blueyed]

Worked on this part a bit: #175