Project: Vcr 2.1.0

Publisher: VCR

Cassette format

VCR Cassettes are files that contain all of the information
about the requests and corresponding responses in a
human-readable/editable format. A cassette contains an array
of HTTP interactions, each of which has the following:

request
- method
- uri
- body
  - encoding
  - string
- headers
response
- status
  - code
  - message
- headers
- body
  - encoding
  - string
- http version

By default, VCR uses YAML to serialize this data. You can configure
VCR to use a different serializer, either on a cassette-by-cassette
basis, or as a default for all cassettes if you use the default_cassette_options.

VCR supports the following serializers out of the box:

:yaml--Uses ruby's standard library YAML. This may use psych or syck, depending on your ruby installation.
:syck--Uses syck (the ruby 1.8 YAML engine). This is useful when using VCR on a project that must run in environments where psych is not available (such as on ruby 1.8), to ensure that syck is always used.
:psych--Uses psych (the new ruby 1.9 YAML engine). This is useful when you want to ensure that psych is always used.
:json--Uses multi_json to serialize the cassette data as JSON.

You can also register a custom serializer using:

VCR.configure do |config|
config.cassette_serializers[:my_custom_serializer] = my_serializer
end

Your serializer must implement the following methods:

file_extension
serialize(hash)
deserialize(string)

Scenarios

Request/Response data is saved to disk as YAML by default
Request/Response data can be saved as JSON
Request/Response data can be saved using a custom serializer

Request/Response data is saved to disk as YAML by default

Given

a file named "cassette_yaml.rb" with:

include_http_adapter_for("http_lib")

if ARGV.any?
  start_sinatra_app(:port => 7777) do
    get('/:path') { ARGV[0] + ' ' + params[:path] }
  end
end

require 'vcr'

VCR.configure do |c|
  configuration
  c.cassette_library_dir = 'cassettes'
end

VCR.use_cassette('example') do
  make_http_request(:get, "http://localhost:7777/foo")
  make_http_request(:get, "http://localhost:7777/bar")
end

When

I run ruby cassette_yaml.rb 'Hello'

Then

the file "cassettes/example.yml" should contain YAML like:

--- 
http_interactions: 
- request: 
    method: get
    uri: http://localhost:7777/foo
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Type: 
      - text/html;charset=utf-8
      Content-Length: 
      - "9"
    body: 
      encoding: UTF-8
      string: Hello foo
    http_version: "1.1"
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
- request: 
    method: get
    uri: http://localhost:7777/bar
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Type: 
      - text/html;charset=utf-8
      Content-Length: 
      - "9"
    body: 
      encoding: UTF-8
      string: Hello bar
    http_version: "1.1"
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
recorded_with: VCR 2.0.0

Examples:
configuration	http_lib
c.hook_into :fakeweb	net/http
c.hook_into :webmock	net/http
c.hook_into :webmock	httpclient
c.hook_into :webmock	patron
c.hook_into :webmock	curb
c.hook_into :webmock	em-http-request
c.hook_into :webmock	typhoeus
c.hook_into :typhoeus	typhoeus
c.hook_into :excon	excon
c.hook_into :faraday	faraday (w/ net_http)

Request/Response data can be saved as JSON

Given

a file named "cassette_json.rb" with:

include_http_adapter_for("net/http")

start_sinatra_app(:port => 7777) do
  get('/:path') { ARGV[0] + ' ' + params[:path] }
end

require 'vcr'

VCR.configure do |c|
  c.hook_into :webmock
  c.cassette_library_dir = 'cassettes'
end

VCR.use_cassette('example', :serialize_with => :json) do
  puts response_body_for(:get, "http://localhost:7777/foo")
  puts response_body_for(:get, "http://localhost:7777/bar")
end

When

I run ruby cassette_json.rb 'Hello'

Then

the file "cassettes/example.json" should contain JSON like:

{
  "http_interactions": [
    {
      "response": {
        "body": {
          "encoding": "UTF-8",
          "string": "Hello foo"
        },
        "http_version": null,
        "status": { "code": 200, "message": "OK" },
        "headers": {
          "Date": [ "Thu, 27 Oct 2011 06:16:31 GMT" ],
          "Content-Type": [ "text/html;charset=utf-8" ],
          "Content-Length": [ "9" ],
          "Server": [ "WEBrick/1.3.1 (Ruby/1.8.7/2011-06-30)" ],
          "Connection": [ "Keep-Alive" ]
        }
      },
      "request": {
        "uri": "http://localhost:7777/foo",
        "body": {
          "encoding": "UTF-8",
          "string": ""
        },
        "method": "get",
        "headers": { }
      },
      "recorded_at": "Tue, 01 Nov 2011 04:58:44 GMT"
    },
    {
      "response": {
        "body": {
          "encoding": "UTF-8",
          "string": "Hello bar"
        },
        "http_version": null,
        "status": { "code": 200, "message": "OK" },
        "headers": {
          "Date": [ "Thu, 27 Oct 2011 06:16:31 GMT" ],
          "Content-Type": [ "text/html;charset=utf-8" ],
          "Content-Length": [ "9" ],
          "Server": [ "WEBrick/1.3.1 (Ruby/1.8.7/2011-06-30)" ],
          "Connection": [ "Keep-Alive" ]
        }
      },
      "request": {
        "uri": "http://localhost:7777/bar",
        "body": {
          "encoding": "UTF-8",
          "string": ""
        },
        "method": "get",
        "headers": { }
      },
      "recorded_at": "Tue, 01 Nov 2011 04:58:44 GMT"
    }
  ],
  "recorded_with": "VCR 2.0.0"
}

When

I run ruby cassette_json.rb

Then

it should pass with:

Hello foo
Hello bar

Request/Response data can be saved using a custom serializer

Given

a file named "cassette_ruby.rb" with:

include_http_adapter_for("net/http")

start_sinatra_app(:port => 7777) do
  get('/:path') { ARGV[0] + ' ' + params[:path] }
end

require 'vcr'

# purely for demonstration purposes; obviously, don't actually
# use ruby #inspect / #eval for your serialization...
ruby_serializer = Object.new
class << ruby_serializer
  def file_extension; "ruby"; end
  def serialize(hash); hash.inspect; end
  def deserialize(string); eval(string); end
end

VCR.configure do |c|
  c.hook_into :webmock
  c.cassette_library_dir = 'cassettes'
  c.cassette_serializers[:ruby] = ruby_serializer
end

VCR.use_cassette('example', :serialize_with => :ruby) do
  puts response_body_for(:get, "http://localhost:7777/foo")
  puts response_body_for(:get, "http://localhost:7777/bar")
end

When

I run ruby cassette_ruby.rb 'Hello'

Then

the file "cassettes/example.ruby" should contain ruby like:

{"http_interactions"=>
  [{"request"=>
     {"method"=>"get",
      "uri"=>"http://localhost:7777/foo",
      "body"=>{"encoding"=>"UTF-8", "string"=>""},
      "headers"=>{"Accept"=>["*/*"], "User-Agent"=>["Ruby"]}},
    "response"=>
     {"status"=>{"code"=>200, "message"=>"OK "},
      "headers"=>
       {"Content-Type"=>["text/html;charset=utf-8"],
        "Content-Length"=>["9"],
        "Connection"=>["Keep-Alive"]},
      "body"=>{"encoding"=>"UTF-8", "string"=>"Hello foo"},
      "http_version"=>nil},
    "recorded_at"=>"Tue, 01 Nov 2011 04:58:44 GMT"},
   {"request"=>
     {"method"=>"get",
      "uri"=>"http://localhost:7777/bar",
      "body"=>{"encoding"=>"UTF-8", "string"=>""},
      "headers"=>{"Accept"=>["*/*"], "User-Agent"=>["Ruby"]}},
    "response"=>
     {"status"=>{"code"=>200, "message"=>"OK "},
      "headers"=>
       {"Content-Type"=>["text/html;charset=utf-8"],
        "Content-Length"=>["9"],
        "Connection"=>["Keep-Alive"]},
      "body"=>{"encoding"=>"UTF-8", "string"=>"Hello bar"},
      "http_version"=>nil},
    "recorded_at"=>"Tue, 01 Nov 2011 04:58:44 GMT"}],
 "recorded_with"=>"VCR 2.0.0"}

When

I run ruby cassette_ruby.rb

Then

it should pass with:

Hello foo
Hello bar

Last published about 6 years ago by myronmarston.

Cassette format

Vcr settings