Default to false and add feature documentation

features/cassettes/drop_unused_requests.feature

@@ -0,0 +1,87 @@
+Feature: Drop Unused Requests
+
+  If set to true, this cassette option will cause VCR to drop any unused requests
+  from the cassette when a cassette is ejected. This is useful for reducing the
+  size of cassettes that contain a large number of requests that are not used.
+
+  The option defaults to false (mostly for backwards compatibility).
+
+  Background:
+    Given a file named "vcr_config.rb" with:
+      """ruby
+      require 'vcr'
+
+      VCR.configure do |c|
+        c.hook_into :webmock
+        c.cassette_library_dir = 'cassettes'
+      end
+      """
+    And a previously recorded cassette file "cassettes/example.yml" with:
+      """
+      --- 
+      http_interactions: 
+      - request: 
+          method: get
+          uri: http://example.com/foo
+          body: 
+            encoding: UTF-8
+            string: ""
+          headers: {}
+        response: 
+          status: 
+            code: 200
+            message: OK
+          headers: 
+            Content-Length: 
+            - "5"
+          body: 
+            encoding: UTF-8
+            string: Existing Response
+          http_version: "1.1"
+        recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
+      recorded_with: VCR 2.0.0
+      """
+
+  Scenario: Unused requests are not dropped from the cassette by default
+    Given a file named "not_dropped_by_default.rb" with:
+      """ruby
+      $server = start_sinatra_app do
+        get('/') { 'New Response' }
+      end
+
+      require 'vcr'
+
+      VCR.configure do |c|
+        c.hook_into :webmock
+        c.cassette_library_dir = 'cassettes'
+      end
+
+      VCR.use_cassette('example', :record => :all) do
+        puts Net::HTTP.get_response('localhost', '/', $server.port).body
+      end
+      """
+    When I run `ruby not_dropped_by_default.rb`
+    Then the file "cassettes/example.yml" should contain "New Response"
+    And the file "cassettes/example.yml" should contain "Existing Response"
+
+  Scenario: Unused requests are dropped from the cassette when the option is set
+    Given a file named "drop_unused_requests_set.rb" with:
+      """ruby
+      $server = start_sinatra_app do
+        get('/') { 'New Response' }
+      end
+
+      require 'vcr'
+
+      VCR.configure do |c|
+        c.hook_into :webmock
+        c.cassette_library_dir = 'cassettes'
+      end
+
+      VCR.use_cassette('example', :record => :all, :drop_unused_requests => true) do
+        puts Net::HTTP.get_response('localhost', '/', $server.port).body
+      end
+      """
+    When I run `ruby drop_unused_requests_set.rb`
+    Then the file "cassettes/example.yml" should contain "New Response"
+    But the file "cassettes/example.yml" should not contain "Existing Response"

features/configuration/default_cassette_options.feature

@@ -88,6 +88,24 @@ Feature: default_cassette_options
     When I run `ruby default_record_on_error.rb`
     Then the output should contain "Record on error: true"
 
+  Scenario: `:drop_unused_requests` defaults to `false` when it has not been set
+    Given a file named "default_drop_unused_requests.rb" with:
+      """ruby
+      require 'vcr'
+
+      VCR.configure do |c|
+        # not important for this example, but must be set to something
+        c.hook_into :webmock
+        c.cassette_library_dir = 'cassettes'
+      end
+
+      VCR.use_cassette('example') do
+        puts "Drop unused requests: #{VCR.current_cassette.drop_unused_requests}"
+      end
+      """
+    When I run `ruby default_drop_unused_requests.rb`
+    Then the output should contain "Drop unused requests: false"
+
   Scenario: cassettes can set their own options
     Given a file named "default_cassette_options.rb" with:
       """ruby

lib/vcr/cassette.rb

@@ -46,6 +46,9 @@ class Cassette
     # @return [Boolean, nil] Should outdated interactions be recorded back to file
     attr_reader :clean_outdated_http_interactions
 
+    # @return [Boolean] Should unused requests be dropped from the cassette?
+    attr_reader :drop_unused_requests
+
     # @return [Array<Symbol>] If set, {VCR::Configuration#before_record} and
     #  {VCR::Configuration#before_playback} hooks with a corresponding tag will apply.
     attr_reader :tags

lib/vcr/configuration.rb

@@ -495,6 +495,7 @@ def initialize
         :record_on_error   => true,
         :match_requests_on => RequestMatcherRegistry::DEFAULT_MATCHERS,
         :allow_unused_http_interactions => true,
+        :drop_unused_requests => false,
         :serialize_with    => :yaml,
         :persist_with      => :file_system,
         :persister_options => {}