Add tests.

guides/design-overview/readme.md

@@ -195,9 +195,15 @@ The value of this uni-directional flow is that it is natural for the stream to b
 Interim responses are responses that are sent before the final response. They are used for things like `103 Early Hints` and `100 Continue`. These responses are sent before the final response, and are used to signal to the client that the server is still processing the request.
 
 ```ruby
+body = Body::Writable.new
+
 interim_response_callback = proc do |status, headers|
-	puts "Interim Response: #{status}: #{headers}"
+	if status == 100
+		# Continue sending the request body.
+		body.write("Hello World")
+		body.close
+	end
 end
 
-response = client.call(request, interim_response: interim_response_callback)
+response = client.post("/upload", {'expect' => '100-continue'}, body, interim_response: interim_response_callback)
 ```

test/protocol/http/request.rb

@@ -70,4 +70,39 @@
 			request.call(connection)
 		end
 	end
+
+	with "interim response" do
+		let(:request) {subject.new("http", "localhost", "GET", "/index.html", "HTTP/1.0", headers, body)}
+
+		it "should call block" do
+			request.on_interim_response do |status, headers|
+				expect(status).to be == 100
+				expect(headers).to be == {}
+			end
+
+			request.send_interim_response(100, {})
+		end
+
+		it "calls multiple blocks" do
+			sequence = []
+
+			request.on_interim_response do |status, headers|
+				sequence << 1
+
+				expect(status).to be == 100
+				expect(headers).to be == {}
+			end
+
+			request.on_interim_response do |status, headers|
+				sequence << 2
+
+				expect(status).to be == 100
+				expect(headers).to be == {}
+			end
+
+			request.send_interim_response(100, {})
+
+			expect(sequence).to be == [2, 1]
+		end
+	end
 end