Centralise usage of listen to wrapper.

gems.rb

@@ -25,4 +25,5 @@
 	gem "bake-test-external"
 
 	gem "sus-fixtures-openssl"
+	gem "sus-fixtures-async"
 end

lib/io/endpoint/bound_endpoint.rb

@@ -12,15 +12,8 @@ class BoundEndpoint < Generic
 		def self.bound(endpoint, backlog: Socket::SOMAXCONN, close_on_exec: false)
 			sockets = endpoint.bind
 
-			sockets.each do |server|
-				# This is somewhat optional. We want to have a generic interface as much as possible so that users of this interface can just call it without knowing a lot of internal details. Therefore, we ignore errors here if it's because the underlying socket does not support the operation.
-				begin
-					server.listen(backlog)
-				rescue Errno::EOPNOTSUPP
-					# Ignore.
-				end
-
-				server.close_on_exec = close_on_exec
+			sockets.each do |socket|
+				socket.close_on_exec = close_on_exec
 			end
 
 			return self.new(endpoint, sockets, **endpoint.options)

lib/io/endpoint/wrapper.rb

@@ -128,7 +128,12 @@ def bind(local_address, protocol: 0, reuse_address: true, reuse_port: nil, linge
 				socket.bind(local_address.to_sockaddr)
 
 				if backlog
-					socket.listen(backlog)
+					begin
+						# Generally speaking, bind/listen is a common pattern, but it's not applicable to all socket types. We ignore the error if it's not supported as the alternative is exposing this upstream, which seems less desirable than handling it here. In other words, `bind` in this context means "prepare it to accept connections", whatever that means for the given socket type.
+						socket.listen(backlog)
+					rescue Errno::EOPNOTSUPP
+						# Ignore.
+					end
 				end
 			rescue
 				socket&.close

test/io/endpoint/bound_endpoint.rb

@@ -26,8 +26,6 @@
 		sockets = internal_endpoint.bind
 		server = sockets.first
 
-		server.listen(1)
-
 		thread = Thread.new do
 			peer, address = server.accept
 			peer.close
@@ -52,8 +50,6 @@
 		sockets = internal_endpoint.bind
 		server = sockets.first
 
-		server.listen(1)
-
 		thread = Thread.new do
 			Thread.current.report_on_exception = false
 

test/io/endpoint/unix_endpoint.rb

@@ -5,6 +5,7 @@
 
 require 'io/endpoint/unix_endpoint'
 require 'with_temporary_directory'
+require 'sus/fixtures/async/reactor_context'
 
 describe IO::Endpoint::UNIXEndpoint do
 	include WithTemporaryDirectory
@@ -54,12 +55,33 @@
 end
 
 describe IO::Endpoint do
-	let(:endpoint) {subject.unix("/tmp/test.ipc")}
+	let(:endpoint) {subject.unix("/tmp/test.ipc", Socket::SOCK_DGRAM)}
 
 	with '.unix' do
 		it "can construct endpoint from path" do
 			expect(endpoint).to be_a(IO::Endpoint::UNIXEndpoint)
 			expect(endpoint).to have_attributes(path: be == "/tmp/test.ipc")
 		end
+
+		with "a simple UDP server" do
+			include Sus::Fixtures::Async::ReactorContext
+
+			it "can send and receive UDP messages" do
+				server_task = Async do
+					endpoint.bind do |server|
+						expect(server).to be_a(Socket)
+						packet, address = server.recvfrom(512)
+
+						expect(packet).to be == "Hello World!"
+					end
+				end
+
+				endpoint.connect do |peer|
+					peer.sendmsg("Hello World!")
+				end
+
+				server_task.wait
+			end
+		end
 	end
 end