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Project: Vcr 2.2.3

Update content_length header

When the :update_content_length_header option is set to a truthy value,
VCR will ensure that the Content-Length header will have the correct
value. This is useful in several situations:

  • When you manually edit the cassette file and change the resonse body length. You can use this option so you don't have to manually calculate and update the body length.
  • When you use ERB, the response body length may vary. This will ensure it is always correct.
  • Syck, the default YAML engine for ruby 1.8 (and 1.9, unless you compile it to use Psych), has a bug where it sometimes will remove some whitespace strings when you serialize them. This may cause the Content-Length header to have the wrong value.

This is especially important when you use a client that checks the
Content-Length header. Mechanize, for example, will raise an EOFError
when the header value does not match the actual body length.

Background
Given
a previously recorded cassette file "cassettes/example.yml" with:
--- 
http_interactions: 
- request: 
    method: get
    uri: http://example.com/
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Type: 
      - text/html;charset=utf-8
      Content-Length: 
      - "11"
    body: 
      encoding: UTF-8
      string: Hello <modified>
    http_version: "1.1"
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
recorded_with: VCR 2.0.0
And
a file named "common_stuff.rb" with:
require 'vcr'

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

def make_request_and_print_results
  response = Net::HTTP.get_response('example.com', '/')
  puts "Body length: #{response.body.length}"
  puts "Header value: #{response['Content-Length']}"
end
Scenarios
Default :update_content_length_header setting
Given
a file named "default.rb" with:
require 'common_stuff'

VCR.use_cassette('example') do
  make_request_and_print_results
end
When
I run ruby default.rb
Then
the output should contain:
Body length: 16
Header value: 11
:update_content_length_header => false
Given
a file named "false.rb" with:
require 'common_stuff'

VCR.use_cassette('example', :update_content_length_header => false) do
  make_request_and_print_results
end
When
I run ruby false.rb
Then
the output should contain:
Body length: 16
Header value: 11
:update_content_length_header => true
Given
a file named "true.rb" with:
require 'common_stuff'

VCR.use_cassette('example', :update_content_length_header => true) do
  make_request_and_print_results
end
When
I run ruby true.rb
Then
the output should contain:
Body length: 16
Header value: 16

Last published almost 5 years ago by myronmarston.