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Project: Vcr 1.10.2

Publisher: VCR

Hooks

VCR provides two global hooks that you can use to customize recording and
playback:

  • before_record: Called before a cassette is written to disk.
  • before_playback: Called before a cassette sets up its stubs for playback.

To use these, call config.before_record or config.before_playback in
your VCR.config block. Provide a block that accepts 0, 1 or 2 arguments.

The first argument, if the block accepts it, will be an HTTP interaction.
Changes you make to the interaction will be reflected in the recording or
playback. You can also call #ignore! on the interaction to cause VCR to
ignore it. It will not be recorded or played back (depending on which
kind of hook you use).

The second argument, if the block accepts it, will be the
VCR::Cassette instance. This may be useful for hooks that you want to
behave differently for different cassettes.

You can also use tagging to apply hooks to particular cassettes. Consider
this code:

VCR.config do |c|
  c.before_record(:twitter) { ... } # modify the interactions somehow
end

VCR.use_cassette('cassette_1', :tag => :twitter) { ... }
VCR.use_cassette('cassette_2') { ... }

In this example, the hook would apply to the first cassette but not the
second cassette.

You can setup as many hooks as you like; each will be invoked at the
appropriate time.

Background
Given
a previously recorded cassette file "cassettes/example.yml" with: 
---
- !ruby/struct:VCR::HTTPInteraction
  request: !ruby/struct:VCR::Request
    method: :get
    uri: http://example.com:80/foo
    body:
    headers:
  response: !ruby/struct:VCR::Response
    status: !ruby/struct:VCR::ResponseStatus
      code: 200
      message: OK
    headers:
      content-type:
      - text/html;charset=utf-8
      content-length:
      - "20"
    body: example.com response
    http_version: "1.1"
Scenarios
  1. Replace sensitive data with before_record hook
  2. Prevent recording by ignoring interaction in before_record hook
  3. Change playback with before_playback hook
  4. Prevent playback by ignoring interaction in before_playback hook
  5. Multiple hooks are run in order
  6. Use tagging to apply hooks to only certain cassettes
Replace sensitive data with before_record hook
Given
a file named "before_record_example.rb" with: 
require 'vcr_cucumber_helpers'

start_sinatra_app(:port => 7777) do
  get('/') { "Hello <secret>" }
end

require 'vcr'

VCR.config do |c|
  c.stub_with :fakeweb
  c.cassette_library_dir = 'cassettes'

  c.before_record do |i|
    i.response.body.sub!(/^Hello .*$/, 'Hello World')
  end

end

VCR.use_cassette('recording_example', :record => :new_episodes) do
  Net::HTTP.get_response('localhost', '/', 7777)
end
When
I run "ruby before_record_example.rb"
Then
the file "cassettes/recording_example.yml" should contain "body: Hello World"
And
the file "cassettes/recording_example.yml" should not contain "secret"
Prevent recording by ignoring interaction in before_record hook
Given
a file named "before_record_ignore.rb" with: 
require 'vcr_cucumber_helpers'

start_sinatra_app(:port => 7777) do
  get('/') { "Hello World" }
end

require 'vcr'

VCR.config do |c|
  c.stub_with :fakeweb
  c.cassette_library_dir = 'cassettes'
  c.before_record { |i| i.ignore! }
end

VCR.use_cassette('recording_example', :record => :new_episodes) do
  response = Net::HTTP.get_response('localhost', '/', 7777)
  puts "Response: #{response.body}"
end
When
I run "ruby before_record_ignore.rb"
Then
it should pass with "Response: Hello World"
And
the file "cassettes/recording_example.yml" should not exist
Change playback with before_playback hook
Given
a file named "before_playback_example.rb" with: 
require 'vcr'

VCR.config do |c|
  c.stub_with                :fakeweb
  c.cassette_library_dir     = 'cassettes'

  c.before_playback do |i|
    i.response.body = 'response from before_playback'
  end
end

VCR.use_cassette('example', :record => :new_episodes) do
  response = Net::HTTP.get_response('example.com', '/foo')
  puts "Response: #{response.body}"
end
When
I run "ruby before_playback_example.rb"
Then
it should pass with "Response: response from before_playback"
Prevent playback by ignoring interaction in before_playback hook
Given
a previously recorded cassette file "cassettes/localhost.yml" with: 
---
- !ruby/struct:VCR::HTTPInteraction
  request: !ruby/struct:VCR::Request
    method: :get
    uri: http://localhost:7777/
    body:
    headers:
  response: !ruby/struct:VCR::Response
    status: !ruby/struct:VCR::ResponseStatus
      code: 200
      message: OK
    headers:
      content-type:
      - text/html;charset=utf-8
      content-length:
      - "20"
    body: recorded response
    http_version: "1.1"
And
a file named "before_playback_ignore.rb" with: 
require 'vcr_cucumber_helpers'

start_sinatra_app(:port => 7777) do
  get('/') { "sinatra response" }
end

require 'vcr'

VCR.config do |c|
  c.stub_with                :fakeweb
  c.cassette_library_dir     = 'cassettes'
  c.before_playback { |i| i.ignore! }
end

VCR.use_cassette('localhost', :record => :new_episodes) do
  response = Net::HTTP.get_response('localhost', '/', 7777)
  puts "Response: #{response.body}"
end
When
I run "ruby before_playback_ignore.rb"
Then
it should pass with "Response: sinatra response"
Multiple hooks are run in order
Given
a file named "multiple_hooks.rb" with: 
require 'vcr_cucumber_helpers'

start_sinatra_app(:port => 7777) do
  get('/') { "Hello World" }
end

require 'vcr'

VCR.config do |c|
  c.stub_with :fakeweb
  c.cassette_library_dir = 'cassettes'

  c.before_record { puts "In before_record hook 1" }
  c.before_record { puts "In before_record hook 2" }

  c.before_playback { puts "In before_playback hook 1" }
  c.before_playback { puts "In before_playback hook 2" }
end

VCR.use_cassette('example', :record => :new_episodes) do
  response = Net::HTTP.get_response('localhost', '/', 7777)
  puts "Response 1: #{response.body}"

  response = Net::HTTP.get_response('example.com', '/foo')
  puts "Response 2: #{response.body}"
end
When
I run "ruby multiple_hooks.rb"
Then
it should pass with: 
In before_playback hook 1
In before_playback hook 2
Response 1: Hello World
Response 2: example.com response
In before_record hook 1
In before_record hook 2
Use tagging to apply hooks to only certain cassettes
Given
a file named "tagged_hooks.rb" with: 
require 'vcr_cucumber_helpers'

start_sinatra_app(:port => 7777) do
  get('/') { "Hello World" }
end

require 'vcr'

VCR.config do |c|
  c.stub_with :fakeweb
  c.cassette_library_dir = 'cassettes'

  c.before_record(:tag_1)   { |i| puts "In before_record hook for tag_1 (#{i.response.body})" }
  c.before_playback(:tag_2) { |i| puts "In before_playback hook for tag_2 (#{i.response.body})" }
end

[:tag_1, :tag_2, nil].each do |tag|
  puts
  puts "Using tag: #{tag.inspect}"

  VCR.use_cassette('example', :record => :new_episodes, :tag => tag) do
    response = Net::HTTP.get_response('localhost', '/', 7777)
    puts "Response 1: #{response.body}"

    response = Net::HTTP.get_response('example.com', '/foo')
    puts "Response 2: #{response.body}"
  end
end
When
I run "ruby tagged_hooks.rb"
Then
it should pass with: 
Using tag: :tag_1
Response 1: Hello World
Response 2: example.com response
In before_record hook for tag_1 (example.com response)
In before_record hook for tag_1 (Hello World)

Using tag: :tag_2
In before_playback hook for tag_2 (example.com response)
In before_playback hook for tag_2 (Hello World)
Response 1: Hello World
Response 2: example.com response

Using tag: nil
Response 1: Hello World
Response 2: example.com response

Last published almost 5 years ago by myronmarston.