Add new :preserve_exact_body_bytes cassette config option.

features/configuration/preserve_exact_body_bytes.feature

@@ -11,7 +11,11 @@ Feature: Preserve Exact Body Bytes
   VCR provides a configuration option to deal with cases like these. The `preserve_exact_body_bytes`
   method accepts a block that VCR will use to determine if the body of the given request or response object
   should be base64 encoded in order to preserve the bytes exactly as-is. VCR does not do this by
-  default, since base64-encoding the string removes the human readibility.
+  default, since base64-encoding the string removes the human readibility of the cassette.
+
+  Alternately, if you want to force an entire cassette to preserve the exact body bytes,
+  you can pass the `:preserve_exact_body_bytes => true` cassette option when inserting your
+  cassette.
 
   Scenario: Preserve exact bytes for response body with invalid encoding
     Given a file named "preserve.rb" with:
@@ -64,3 +68,36 @@ Feature: Preserve Exact Body Bytes
       "body":{"encoding":"ASCII-8BIT","base64_string":"YWJjIPo=\n"}
       """
 
+  Scenario: Preserve exact bytes for cassette with `:preserve_exact_body_bytes` option
+    Given a file named "preserve.rb" with:
+      """ruby
+      start_sinatra_app(:port => 7777) do
+        get('/') { "Hello World" }
+      end
+
+      require 'vcr'
+
+      VCR.configure do |c|
+        c.cassette_library_dir = 'cassettes'
+        c.hook_into :fakeweb
+        c.default_cassette_options = { :serialize_with => :json }
+      end
+
+      VCR.use_cassette('preserve_bytes', :preserve_exact_body_bytes => true) do
+        Net::HTTP.get_response(URI("http://localhost:7777/"))
+      end
+
+      VCR.use_cassette('dont_preserve_bytes') do
+        Net::HTTP.get_response(URI("http://localhost:7777/"))
+      end
+      """
+    When I run `ruby preserve.rb`
+    Then the file "cassettes/preserve_bytes.json" should contain:
+      """
+      "body":{"encoding":"US-ASCII","base64_string":"SGVsbG8gV29ybGQ=\n"}
+      """
+     And the file "cassettes/dont_preserve_bytes.json" should contain:
+      """
+      "body":{"encoding":"US-ASCII","string":"Hello World"}
+      """
+

lib/vcr.rb

@@ -83,6 +83,9 @@ def current_cassette
   # @option options :serialize_with [Symbol] Which serializer to use.
   #  Valid values are :yaml, :syck, :psych, :json or any registered
   #  custom serializer. Defaults to :yaml.
+  # @option options :preserve_exact_body_bytes [Boolean] Whether or not
+  #  to base64 encode the bytes of the requests and responses for this cassette
+  #  when serializing it. See also `VCR::Configuration#preserve_exact_body_bytes`.
   #
   # @return [VCR::Cassette] the inserted cassette
   #

lib/vcr/cassette.rb

@@ -50,7 +50,7 @@ def initialize(name, options = {})
       invalid_options = options.keys - [
         :record, :erb, :match_requests_on, :re_record_interval, :tag, :tags,
         :update_content_length_header, :allow_playback_repeats, :exclusive,
-        :serialize_with
+        :serialize_with, :preserve_exact_body_bytes
       ]
 
       if invalid_options.size > 0
@@ -64,6 +64,7 @@ def initialize(name, options = {})
       @re_record_interval           = options[:re_record_interval]
       @tags                         = Array(options.fetch(:tags) { options[:tag] })
       @tags                         << :update_content_length_header if options[:update_content_length_header]
+      @tags                         << :preserve_exact_body_bytes if options[:preserve_exact_body_bytes]
       @allow_playback_repeats       = options[:allow_playback_repeats]
       @exclusive                    = options[:exclusive]
       @serializer                   = VCR.cassette_serializers[options[:serialize_with]]

lib/vcr/configuration.rb

@@ -441,7 +441,9 @@ def register_built_in_hooks
         interaction.response.update_content_length_header
       end
 
-      preserve_exact_body_bytes { false }
+      preserve_exact_body_bytes do |http_message, cassette|
+        cassette && cassette.tags.include?(:preserve_exact_body_bytes)
+      end
     end
   end
 

spec/vcr/configuration_spec.rb

@@ -212,8 +212,20 @@ def message_for(body)
       stub(:body => body)
     end
 
-    it "returns false by default" do
-      subject.preserve_exact_body_bytes_for?(message_for "string").should be_false
+    context "default hook" do
+      it "returns false when there is no current cassette" do
+        subject.preserve_exact_body_bytes_for?(message_for "string").should be_false
+      end
+
+      it "returns false when the current cassette has been created without the :preserve_exact_body_bytes option" do
+        VCR.insert_cassette('foo')
+        subject.preserve_exact_body_bytes_for?(message_for "string").should be_false
+      end
+
+      it 'returns true when the current cassette has been created with the :preserve_exact_body_bytes option' do
+        VCR.insert_cassette('foo', :preserve_exact_body_bytes => true)
+        subject.preserve_exact_body_bytes_for?(message_for "string").should be_true
+      end
     end
 
     it "returns true when the configured block returns true" do