(Update: I've packaged this gist into a gem to make its use easier, see: https://github.com/gonzalo-bulnes/dredd-rack.) Add validation against an API blueprint to a Ruby test suite (by defining a Rake task).

Rakefile

# Rakefile

# Add Rainbow to the app dependencies. That's optional, but the result is worth it.
require 'rainbow'

# ...

# Validate an API against its API blueprint
#
# The API blueprints are expected to be stored in `doc/` and
# have the `.apib` or `.apib.md` extension. (The last one ensures
# that the blueprints are rendered as HTML on Github.)
#
# The 'blueprint:verify' task depends on Dredd being installed but
# does detect automatically if it is not and provides instructions
# to install it.
#
# The task also depends on the API being served at the API_HOST URL.
# It also detects when the connection is impossible and suggests to
# set the API_HOST environment variable and start the API server.
#
# Usage:
#
#     API_HOST=http://localhost:4567 rake 'blueprint:verify'
#
# Returns nothing but does abort the rake tasks suite