Exclusive Cassette

VCR allows cassettes to be nested. This is particularly useful in a context like cucumber, where you may be using a cassette for an entire scenario, and also using a cassette within a particular step definition.

By default, both the inner and outer cassettes are active. On each request, VCR will look for a matching HTTP interaction in the inner cassette, and it will use the outer cassette as a fall back if none can be found.

If you do not want the HTTP interactions of the outer cassette considered, you can pass the :exclusive option, so that the inner cassette is used exclusively.

Background ()

Given a previously recorded cassette file "cassettes/outer.yml" with:

--- 
http_interactions: 
- request: 
    method: get
    uri: http://localhost/outer
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Length: 
      - "18"
    body: 
      encoding: UTF-8
      string: Old outer response
    http_version: "1.1"
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
recorded_with: VCR 2.0.0

And a previously recorded cassette file "cassettes/inner.yml" with:

--- 
http_interactions: 
- request: 
    method: get
    uri: http://localhost/inner
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Length: 
      - "18"
    body: 
      encoding: UTF-8
      string: Old inner response
    http_version: "1.1"
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
recorded_with: VCR 2.0.0

And a file named "setup.rb" with:

include_http_adapter_for("net/http")

$server = start_sinatra_app do
  get('/:path') { "New #{params[:path]} response" }
end

require 'vcr'

VCR.configure do |c|
  c.hook_into :webmock
  c.cassette_library_dir = 'cassettes'
  c.default_cassette_options = {
    :record => :new_episodes,
    :match_requests_on => [:method, :host, :path]
  }
end

Cassettes are not exclusive by default

Given a file named "not_exclusive.rb" with:

require 'setup'

VCR.use_cassette('outer') do
  VCR.use_cassette('inner') do
    puts response_body_for(:get, "http://localhost:#{$server.port}/outer")
    puts response_body_for(:get, "http://localhost:#{$server.port}/inner")
  end
end

When I run ruby not_exclusive.rb

Then it should pass with:

Old outer response
Old inner response

Use an exclusive cassette

Given a file named "exclusive.rb" with:

require 'setup'

VCR.use_cassette('outer') do
  VCR.use_cassette('inner', :exclusive => true) do
    puts response_body_for(:get, "http://localhost:#{$server.port}/outer")
    puts response_body_for(:get, "http://localhost:#{$server.port}/inner")
  end
end

When I run ruby exclusive.rb

Then it should pass with:

New outer response
Old inner response

And the file "cassettes/inner.yml" should contain "New outer response".