Running Specs From Vim

Test driven development thrives on a tight feedback loop. However, switching from the editor to the shell to manually run specs is inefficient.

Tools such as autotest and guard run specs whenever a file gets saved. Although an improvement over a manual workflow, those approaches often run the suite when not needed and run too many or too few specs.

Enter vim-rspec, a lightweight vim plugin that runs specs directly from within vim with the press of a key.

It exposes methods such as RunNearestSpec(), RunCurrentSpecFile(), and RunLastSpec(), which can be bound to a key mapping of your choice. In thoughtbot/dotfiles, we bind those methods to <Leader>s, <Leader>t, and <Leader>l.

Cursor over any line within an RSpec spec like this:

describe RecipientInterceptor do
  it 'overrides to/cc/bcc fields' do
    Mail.register_interceptor RecipientInterceptor.new(recipient_string)

    response = deliver_mail

    expect(response.to).to eq [recipient_string]
    expect(response.cc).to eq []
    expect(response.bcc).to eq []
  end
end

Type <Leader>s:

rspec spec/recipient_interceptor_spec.rb:4
Run options: include
{:locations=>{"spec/recipient_interceptor_spec.rb"=>[4]}}
.

Finished in 0.03059 seconds
1 example, 0 failures

The screen is overtaken by a shell that runs just that focused spec. Developers using tmux with vim-rspec and tslime sometimes send the output to a nearby shell so the code and spec output display on the screen at the same time.

Feeling good that this new spec passes, run the whole file’s specs with <Leader>t to make sure the class’s entire functionality is still intact:

rspec spec/recipient_interceptor_spec.rb
......

Finished in 0.17752 seconds
6 examples, 0 failures

Red, green, refactor. From within the application’s or library’s code:

def delivering_email(message)
  add_custom_headers message
  add_subject_prefix message
  message.to = @recipients
  message.cc = []
  message.bcc = []
end

Run <Leader>l without having to switch back to the spec:

rspec spec/recipient_interceptor_spec.rb
......

Finished in 0.17752 seconds
6 examples, 0 failures

These tight feedback loops make TDD easier by eliminating the switching cost between editor to the shell when running specs.

What’s next

If you found this useful, you might also enjoy:

• Running Specs from Vim, Sent to tmux Via Tslime
• Use RSpec.vim with tmux and Dispatch
• Destroy All Software for screencasts showing this and other productivity techniques with specs and Vim