Provides assertions that allow direct PNG comparison via ChunkyPNG.
Add this line to your application's Gemfile:
gem 'minitest-pngdiff'And then execute:
$ bundle
Or install it yourself as:
$ gem install minitest-pngdiff
assert_png_diff(png1, png2, threshold, diff_method: :distance, msg: nil)
Provide this assertion with two PNGs (can be file paths, PNG blobs, or IO objects) and a difference threshold for success/failure. Optionally, provide a method of pixel difference calculation (only :distance right now) or a custom message.
Use refute_png_diff for refuting two PNG diffs.
assert_png_equal(png1, png2, threshold, msg: nil
Used like assert_png_diff but assumes that you want a difference threshold of 0.0. See refute_png_equal to refute two PNGs having a difference threshold of 0.
After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.
To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.
Bug reports and pull requests are welcome on GitHub at https://github.com/customink/minitest-pngdiff. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.
The gem is available as open source under the terms of the MIT License.