More test coverage / compatibility.

lib/protocol/http/body/file.rb

@@ -73,7 +73,7 @@ def stream?
 				end
 
 				def call(stream)
-					IO.copy_stream(@file, stream)
+					IO.copy_stream(@file, stream, @remaining)
 				end
 
 				def join

lib/protocol/http/body/readable.rb

@@ -94,6 +94,10 @@ def join
 					end
 				end
 
+				def stream?
+					false
+				end
+
 				# Write the body to the given stream.
 				#
 				# In some cases, the stream may also be readable, such as when hijacking an HTTP/1 connection. In that case, it may be acceptable to read and write to the stream directly.
@@ -123,6 +127,7 @@ def as_json(...)
 					{
 						class: self.class.name,
 						length: self.length,
+						stream: self.stream?,
 						ready: self.ready?,
 						empty: self.empty?
 					}

lib/protocol/http/body/wrapper.rb

@@ -50,11 +50,6 @@ def rewindable?
 					@body.rewindable?
 				end
 
-				def stream?
-					# Most wrappers are not streamable by default.
-					false
-				end
-
 				def length
 					@body.length
 				end

test/protocol/http/body/file.rb

@@ -85,5 +85,17 @@
 
 			expect(output.string).to be == "Hello World"
 		end
+
+		with "/dev/zero" do
+			it "can stream partial output" do
+				skip unless File.exist?('/dev/zero')
+
+				body = subject.open('/dev/zero', 0...10)
+
+				body.call(output)
+
+				expect(output.string).to be == "\x00" * 10
+			end
+		end
 	end
 end

test/protocol/http/body/readable.rb

@@ -63,6 +63,7 @@
 			expect(body.as_json).to have_keys(
 				class: be == subject.name,
 				length: be_nil,
+				stream: be == false,
 				ready: be == false,
 				empty: be == false,
 			)