VCR: Better Binary Serializer

What

This gem is a VCR serializer which persists any binary data in the HTTP request or response bodies outside the cassette.

Why

• Keeps the cassettes human readable
• You can git diff the cassette more easily (and git won't diff the binary data stored elsewhere)
• Github won't collapse the diffs for cassettes in PRs (the default for large files)

How

Add the gem to your Gemfile and bundle install:

group :test do
  gem "vcr_better_binary"
end

Configure VCR to use the serializer:

# spec/support/vcr.rb (or wherever you configure VCR)

VCR.configure do |config|
  config.cassette_serializers[:better_binary] = VcrBetterBinary::Serializer.new
  config.default_cassette_options = { serialize_with: :better_binary } # or specify inline in 'VCR.use_cassette'
end

When you re-record or delete a cassette there may be stale references leftover in the storage directory.

Add a hook after all your tests have run to prevent unused data from building up:

RSpec.configure do |config|
  config.after(:suite) do
    VcrBetterBinary::Serializer.new.prune_bin_data
  end
end

And you're set!

The end-result

When you record requests with binary data the resulting cassette will look similar to this:

# Abridged example
http_interactions:
- request:
    method: post
    uri: https://example.com/upload
    body:
      encoding: ASCII-8BIT
      bin_key: lymom-vudim-vunek-mobad-fepak-taset-zosyl-zuhaf-setag
  response:
    status:
      code: 200
      message: OK
    body:
      encoding: ASCII-8BIT
      bin_key: xohog-badok-paneg-memek-tahum-degab-kasip-pefik-colol

And the following files will have been persisted:

spec/fixtures/vcr_cassettes
├── my-cassette.yml
└── bin_data
    ├── lymom-vudim-vunek-mobad-fepak-taset-zosyl-zuhaf-setag
    └── xohog-badok-paneg-memek-tahum-degab-kasip-pefik-colol

All remaining VCR functionality will operate as normal; the only adjustment is the storage of binary data.

Advanced configuration

You can adjust the underlying serializer to save your cassettes in different formats, e.g:

# JSON cassettes
VcrBetterBinary::Serializer.new(base_serializer: VCR::Cassette::Serializers::JSON)