Custom RSpec be_square matcher for CarrierWave

It seems to me that when using CarrierWave for image uploads, particularly user avatars, it would be a pretty common thing to generate at least one square-cropped version of the image. CarrierWave ships with some nice custom matchers to test exact dimensions and such, but I found I wanted a way to just test that an image was square.

I did this using by building a custom matcher on top of the ones CarrierWave provides. If you have the conventional spec_helper.rb that requires support/**/*.rb, then you can just drop this somewhere like support/matchers/carrierwave_matchers.rb:

	require 'carrierwave/test/matchers'
	module CarrierWave
	module Test
	module Matchers
	class BeSquare
	def matches?(actual)
	@actual = actual
	image = ImageLoader.load_image(@actual.current_path)
	@actual_width = image.width
	@actual_height = image.height
	@actual_width == @actual_height
	end
	def failure_message
	"expected #{@actual.current_path.inspect} to be square, but it was #{@actual_width} by #{@actual_height}."
	end
	def negative_failure_message
	"expected #{@actual.current_path.inspect} to not be square, but it was #{@actual_width} by #{@actual_height}"
	end
	end
	def be_square
	BeSquare.new
	end
	end
	end
	end

view raw carrierwave_matchers.rb hosted with ❤ by GitHub

Then, you can use this like:

	require 'spec_helper'
	describe AvatarUploader do
	include CarrierWave::Test::Matchers
	before :all do
	AvatarUploader.enable_processing = true
	@uploader = AvatarUploader.new(@user, :avatar)
	@uploader.store!(File.open(SOME_FILE_NAME))
	end
	after :all do
	@uploader.remove!
	AvatarUploader.enable_processing = false
	end
	describe "the main version" do
	it "should be no larger than 512 by 512 pixels" do
	@uploader.should be_no_larger_than(512, 512)
	end
	end
	describe "the square version" do
	it "should be square" do
	@uploader.square.should be_square
	end
	end
	end

view raw avatar_uploader_spec.rb hosted with ❤ by GitHub