Reading the binary body of a VCR cassette

Working with VCR is great until you record a response that came with Content-Encoding: gzip and open the YAML to find incomprehensible bytes. The snippet below loads the cassette and prints the body as a string.

require 'yaml'

path = 'spec/vcr_cassettes/cassette.yml'
deserialized = YAML.load_file(path)
body_string = deserialized['http_interactions'][0]['response']['body']['string']

puts body_string

If the body is gzipped, add this:

require 'zlib'
require 'stringio'

decoded = Zlib::GzipReader.new(StringIO.new(body_string)).read
puts decoded

Reference I used: lapointexavier’s gist.

Why this is useful

Unreadable cassettes hide bugs. When a test fails with “expected X, got nothing”, opening the cassette and seeing the actual JSON usually saves 20 minutes of guessing.