RSpecSnapshotMatcher

This gem was inspired by the snapshot feature of Facebook's Jest Javascript testing framework. At first, I considered the behavior of dubious value because it seemed like it is largely an implementation of the Guru Checks Output anti-pattern.

If you find yourself in a situation where it is difficult to refactor confidently because you have missing coverage in other test suites, then the snapshot matcher can give you a quick and dirty sanity check.

Add this line to your application's Gemfile:

gem 'rspec_snapshot_matcher'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rspec_snapshot_matcher

In your rspec helper

require 'rspec_snapshot_matcher'

Then, in your tests, use the matcher to compare an object to the snapshot for that test.

describe 'some request, method, whatever' do
  it 'should render the desired html, string, hash, object, struct, ... you name it' do
    get some_path
    expect(response.body).to match_snapshot
  end

  it 'should work with just about anything really' do
    model = service.get_something
    expect(model).to match_snapshot
  end
end

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/[USERNAME]/rspec-snapshot-matcher.

The gem is available as open source under the terms of the MIT License.