Register and Use a Custom Matcher

If the built-in matchers do not meet your needs, you can use a custom matcher.

Any 2-argument callable (that is, an object that responds to #call and accepts 2 arguments) can be a matcher. Simply put the callable in your :match_requests_on array.

In addition, you can register a named custom matcher with VCR, and use the name in your :match_requests_on array.

Either way, your custom matcher should return a truthy value if the given requests should be considered equivalent.

Background ()

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

--- 
http_interactions: 
- request: 
    method: get
    uri: http://foo.com:9000/foo
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Length: 
      - "18"
    body: 
      encoding: UTF-8
      string: port 9000 response
    http_version: "1.1"
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
- request: 
    method: get
    uri: http://foo.com:8000/foo
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Length: 
      - "18"
    body: 
      encoding: UTF-8
      string: port 8000 response
    http_version: "1.1"
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
recorded_with: VCR 2.0.0

Use a callable as a custom request matcher

And a file named "callable_matcher.rb" with:

include_http_adapter_for("<http_lib>")

require 'vcr'

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

port_matcher = lambda do |request_1, request_2|
  URI(request_1.uri).port == URI(request_2.uri).port
end

VCR.use_cassette('example', :match_requests_on => [:method, port_matcher]) do
  puts "Response for port 8000: " + response_body_for(:get, "http://example.com:8000/")
end

VCR.use_cassette('example', :match_requests_on => [:method, port_matcher]) do
  puts "Response for port 9000: " + response_body_for(:get, "http://example.com:9000/")
end

When I run ruby callable_matcher.rb

Then it should pass with:

Response for port 8000: port 8000 response
Response for port 9000: port 9000 response

Examples

configuration	http_lib
c.hook_into :webmock	net/http
c.hook_into :webmock	httpclient
c.hook_into :webmock	curb
c.hook_into :webmock	patron
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)
c.hook_into :faraday	faraday (w/ typhoeus)

Register a named custom matcher

And a file named "register_custom_matcher.rb" with:

include_http_adapter_for("net/http")

require 'vcr'

VCR.configure do |c|
  c.hook_into :webmock
  c.cassette_library_dir = 'cassettes'
  c.register_request_matcher :port do |request_1, request_2|
    URI(request_1.uri).port == URI(request_2.uri).port
  end
end

VCR.use_cassette('example', :match_requests_on => [:method, :port]) do
  puts "Response for port 8000: " + response_body_for(:get, "http://example.com:8000/")
end

VCR.use_cassette('example', :match_requests_on => [:method, :port]) do
  puts "Response for port 9000: " + response_body_for(:get, "http://example.com:9000/")
end

When I run ruby register_custom_matcher.rb

Then it should pass with:

Response for port 8000: port 8000 response
Response for port 9000: port 9000 response