Running Specs from Vim, Sent to tmux via Tslime

When I first started working at thoughtbot, I was impressed to see some of my colleagues sending the current spec in vim to a tmux pane with the press of a key. This makes for an very fast testing/feedback loop and streamlines the TDD process.

Determining which spec(s) to run

We don’t always want to run the full test suite. Often, we just want to run a single spec or even a single example. We recently released vim-rspec, a vim plugin that allows us to run the desired set of specs with the press of a key.

Sending the spec command

vim-rspec only does half the job however. We need a second component to send the commands from vim to the desired tmux pane. tslime.vim is a plugin that does exactly that by providing a Send_to_Tmux() function.

Tying it all together

First install vim-rspec and tslime.vim using Vundle:

Bundle 'thoughtbot/vim-rspec'
Bundle 'jgdavey/tslime.vim'

Add the following to your .vimrc:

let g:rspec_command = 'call Send_to_Tmux("rspec {spec}\n")'

This tells vim-rspec to use Send_to_Tmux to run the selected specs.

Finally, all this wouldn’t be of much use if we couldn’t run it at the press of a key. Add these keybindings to your .vimrc (this step is unnecessary if you’re using thoughtbot/dotfiles):

" vim-rspec mappings
map <Leader>t :call RunCurrentSpecFile()<CR>
map <Leader>s :call RunNearestSpec()<CR>
map <Leader>l :call RunLastSpec()<CR>
map <Leader>a :call RunAllSpecs()<CR>

Thats all you have to do! The first time you run a spec this way, you will be asked to input the names of your tmux session, window and pane (protip, you can tab-complete these). Every subsequent time, your tests will just magically run in the desired pane without you ever needing to leave vim.


You can completely customize the command that gets sent to your tmux pane. For example, to run the specs using Spring you would use

let g:rspec_command = 'call Send_to_Tmux("spring rspec {spec}\n")'

Take control of your terminal and build your ideal development workflow. Our Tmux Course will teach you the ins and outs of tmux for terminal mastery.