VCR to Pacto

spec_helper.rb

def vcr_to_pacto_request vcr_request
  uri = URI(vcr_request.uri)
  definition = {
    'method' => vcr_request.method,
    'path' => uri.path,
    # How do we get params from VCR?
    'params' => {},
    'headers' => vcr_request.headers
  }
  Pacto::Request.new uri.host, definition
end

def vcr_to_pacto_response vcr_response
  OpenStruct.new(
    'status' => vcr_response.status.code,
    'headers' => vcr_response.headers,
    'body' => vcr_response.body
  )
end

Pacto.configure do |c|
  c.contracts_path = 'contracts'
end

VCR.configure do |c|
  # ...
  if ENV['PACTO'] == 'generate'
    c.before_playback do | interaction |
      uri = URI(interaction.request.uri)
      basename = File.basename(uri.path, '.json') + '.json'
      # contract_file = File.expand_path(Pacto.configuration.contracts_path, File.dirname(uri.path), basename)
      contract_file = File.join(Pacto.configuration.contracts_path, File.dirname(uri.path), basename)

      unless File.exists? contract_file
        pacto_request = vcr_to_pacto_request(interaction.request)
        pacto_response = vcr_to_pacto_response(interaction.response)
        generator = Pacto::Generator.new
        FileUtils.mkdir_p(File.dirname contract_file)
        File.write(contract_file, generator.save('vcr', pacto_request, pacto_response))
      end
    end
  end
end

wow! that's really cool! Can you post a generated contract?

I asked @fernando-alves if he can work on a PR that makes the generator only record request headers that appear in the Vary. That's exactly what Vary is supposed to tell us, right? We'd still need a way to clean up response headers, though.

Also, the schema generator doesn't request default values right now, but that should be a pretty easy enhancement.

I'd also prefer the description ("Generated from ...") at the top of the Contract, instead of in the body.

The generated contract (with the extra request headers dropped), would look like this:

{
  "request": {
    "headers": {
      "X-Auth-Token": [
        "_ONE-TIME-TOKEN_"
      ]
    },
    "method": "get",
    "params": {
    },
    "path": "/v1.0/000000/flavors/1.json"
  },
  "response": {
    "headers": {
      "vary": [
        "Accept, Accept-Encoding, X-Auth-Token"
      ],
      "Last-Modified": [
        "Wed, 19 Sep 2007 18:24:59 GMT"
      ],
      "X-PURGE-KEY": [
        "/flavors"
      ],
      "Cache-Control": [
        "s-maxage=1800"
      ],
      "Content-Type": [
        "application/json"
      ],
      "X-Varnish": [
        "_VARNISH-REQUEST-ID_"
      ],
      "Age": [
        "0"
      ],
      "Via": [
        "1.1 varnish"
      ]
    },
    "status": 200,
    "body": {
      "$schema": "http://json-schema.org/draft-03/schema#",
      "description": "Generated from vcr with shasum 8bc264c0741af280ceabf118834194374ab86bc4",
      "type": "object",
      "required": true,
      "properties": {
        "flavor": {
          "type": "object",
          "required": true,
          "properties": {
            "id": {
              "type": "integer",
              "required": true
            },
            "ram": {
              "type": "integer",
              "required": true
            },
            "disk": {
              "type": "integer",
              "required": true
            },
            "name": {
              "type": "string",
              "required": true
            }
          }
        }
      }
    }
  }
}