allow to pass a custom body class, which only needs to implement the constructor signature and #<<

lib/httpx/options.rb

@@ -53,6 +53,7 @@ module HTTPX
         :request_class            => Class.new(Request),
         :response_class           => Class.new(Response),
         :headers_class            => Class.new(Headers),
+        :response_body_class      => Response::Body,
       }
 
       defaults.merge!(options)
@@ -92,7 +93,7 @@ module HTTPX
     %w[
       params form json body
       proxy follow ssl max_retries
-      request_class response_class headers_class
+      request_class response_class headers_class response_body_class
       io
     ].each do |method_name|
       def_option(method_name)

lib/httpx/response.rb

@@ -16,13 +16,15 @@ module HTTPX
     def_delegator :@body, :read
     
     def_delegator :@body, :copy_to
+    
+    def_delegator :@body, :close
 
     def initialize(request, status, headers, **options)
       @options = Options.new(options) 
       @request = request
       @status = Integer(status)
       @headers = @options.headers_class.new(headers)
-      @body = Body.new(self, threshold_size: @options.body_threshold_size)
+      @body = @options.response_body_class.new(self, threshold_size: @options.body_threshold_size)
     end 
 
     def <<(data)

test/http1_test.rb

@@ -150,6 +150,36 @@ class HTTP1Test < Minitest::Spec
     io.close if io 
   end
 
+   def test_http_buffer_to_custom
+     uri = build_uri("/")
+     custom_body = Class.new do 
+      attr_reader :file
+
+      def initialize(response, **)
+        @file = Tempfile.new
+      end
+
+      def <<(data)
+        @file << data
+      end
+
+      def close
+        return unless @file
+        @file.close
+        @file.unlink
+      end
+    end
+
+    response = HTTPX.get(uri, response_body_class: custom_body)
+    assert response.status == 200, "status is unexpected"
+    assert response.body.is_a?(custom_body), "body should be from custom type"
+    file = response.body.file
+    file.rewind
+    assert file.size == response.headers["content-length"].to_i, "didn't buffer the whole body"
+  ensure
+    response.close if response
+  end
+   
   private
 
   def json_body(response)

test/options_test.rb

@@ -75,6 +75,7 @@ class OptionsSpec < Minitest::Test
       :request_class      => bar.request_class,
       :response_class     => bar.response_class,
       :headers_class      => bar.headers_class,
+      :response_body_class => bar.response_body_class,
     }, "options haven't merged correctly"
   end
 

test/response_test.rb

@@ -16,7 +16,7 @@ class ResponseTest < Minitest::Test
     assert resource.headers.is_a?(Headers), "headers should have been coerced" 
   end
 
-  def test_response_body_concat
+  def test_response_body_write
     assert resource.body.empty?, "body should be empty after init"
     resource << "data"
     assert resource.body == "data", "body should have been updated"