Expanded interface Head.for(body, length) to support nil body and optional length. (#83)

Author: samuel-williams-shopify

lib/protocol/http/body/head.rb

@@ -12,12 +12,24 @@ module Body
 			# Represents a body suitable for HEAD requests, in other words, a body that is empty and has a known length.
 			class Head < Readable
 				# Create a head body for the given body, capturing its length and then closing it.
-				def self.for(body)
-					head = self.new(body.length)
-					
-					body.close
+				#
+				# If a body is provided, the length is determined from the body, and the body is closed.
+				# If no body is provided, and the content length is provided, a head body is created with that length.
+				# This is useful for creating a head body when you only know the content length but not the actual body, which may happen in adapters for HTTP applications where the application may not provide a body for HEAD requests, but the content length is known.
+				#
+				# @parameter body [Readable | Nil] the body to create a head for.
+				# @parameter length [Integer | Nil] the content length of the body, if known.
+				# @returns [Head | Nil] the head body, or nil if the body is nil.
+				def self.for(body, length = nil)
+					if body
+						head = self.new(body.length)
+						body.close
+						return head
+					elsif length
+						return self.new(length)
+					end
 
-					return head
+					return nil
 				end
 
 				# Initialize the head body with the given length.

releases.md

@@ -4,6 +4,7 @@
 
   - `Protocol::HTTP::Headers` now raise a `DuplicateHeaderError` when a duplicate singleton header (e.g. `content-length`) is added.
   - `Protocol::HTTP::Headers#add` now coerces the value to a string when adding a header, ensuring consistent behaviour.
+  - `Protocol::HTTP::Body::Head.for` now accepts an optional `length` parameter, allowing it to create a head body even when the body is not provided, based on the known content length.
 
 ## v0.50.0
 

test/protocol/http/body/head.rb

@@ -46,14 +46,33 @@
 	end
 
 	with ".for" do
-		let(:source) {Protocol::HTTP::Body::Buffered.wrap("!")}
-		let(:body) {subject.for(source)}
+		with "body" do
+			let(:source) {Protocol::HTTP::Body::Buffered.wrap("!")}
+			let(:body) {subject.for(source)}
+			
+			it "captures length and closes existing body" do
+				expect(source).to receive(:close)
+				
+				expect(body).to have_attributes(length: be == 1)
+				body.close
+			end
+		end
 
-		it "captures length and closes existing body" do
-			expect(source).to receive(:close)
+		with "content length" do
+			let(:body) {subject.for(nil, 42)}
 
-			expect(body).to have_attributes(length: be == 1)
-			body.close
+			it "uses the content length if no body is provided" do
+				expect(body).to have_attributes(length: be == 42)
+				expect(body).to be(:empty?)
+				expect(body).to be(:ready?)
+			end
+		end
+	end
+	
+	with ".for with nil body" do
+		it "returns nil when body is nil" do
+			body = subject.for(nil)
+			expect(body).to be_nil
 		end
 	end
 end