Fix null services.

Author: ioquatix

fixtures/async/service/good_interface.rb

@@ -0,0 +1,9 @@
+module Async
+	module Service
+		module GoodInterface
+			def good_method
+				:good
+			end
+		end
+	end
+end

fixtures/async/service/sleep_service.rb

@@ -0,0 +1,36 @@
+require 'async/service/generic'
+
+module Async
+	module Service
+		class SleepService < Async::Service::Generic
+			def setup(container)
+				super
+				
+				container.run(count: 1, restart: true) do |instance|
+					# Use log level:
+					Console.logger.level = @environment.evaluator.log_level
+					
+					if container.statistics.failed?
+						Console.debug(self, "Child process restarted #{container.statistics.restarts} times.")
+					else
+						Console.debug(self, "Child process started.")
+					end
+
+					instance.ready!
+
+					while true
+						sleep 1
+
+						Console.debug(self, "Work")
+
+						if rand < 0.1
+							Console.debug(self, "Should exit...")
+							sleep 0.5
+							exit(1)
+						end
+					end
+				end
+			end	
+		end
+	end
+end

lib/async/service/configuration.rb

@@ -51,9 +51,11 @@ def services(implementing: nil)
 				return to_enum(:services, implementing: implementing) unless block_given?
 
 				@environments.each do |environment|
-					next if implementing and environment.implements?(implementing)
-					
-					yield Generic.wrap(environment)
+					if implementing.nil? or environment.implements?(implementing)
+						if service = Generic.wrap(environment)
+							yield service
+						end
+					end
 				end
 			end
 

lib/async/service/generic.rb

@@ -12,11 +12,14 @@ module Service
 		class Generic
 			# Convert the given environment into a service if possible.
 			# @parameter environment [Build::Environment] The environment to use to construct the service.
+			# @returns [Generic | Nil] The constructed service if the environment specifies a service class.
 			def self.wrap(environment)
 				evaluator = environment.evaluator
 
-				if service_class = evaluator.service_class || self
-					return service_class.new(environment, evaluator)
+				if evaluator.key?(:service_class)
+					if service_class = evaluator.service_class
+						return service_class.new(environment, evaluator)
+					end
 				end
 			end
 

test/async/service/.configurations/implementing.rb

@@ -0,0 +1,19 @@
+#!/usr/bin/env async-service
+# frozen_string_literal: trueb
+
+# Released under the MIT License.
+# Copyright, 2025, by Samuel Williams.
+
+require "async/service/good_interface"
+require "async/service/sleep_service"
+
+# A service without a service class, e.g. a no-op.
+service "good-service" do
+	include Async::Service::GoodInterface
+	
+	service_class Async::Service::SleepService
+end
+
+service "not-so-good-service" do
+	service_class Async::Service::SleepService
+end

test/async/service/.configurations/null.rb

@@ -0,0 +1,9 @@
+#!/usr/bin/env async-service
+# frozen_string_literal: trueb
+
+# Released under the MIT License.
+# Copyright, 2025, by Samuel Williams.
+
+# A service without a service class, e.g. a no-op.
+service "null" do
+end

test/async/service/.configurations/sleep.rb

@@ -8,45 +8,15 @@
 	log_level :info
 end
 
-# A test service:
-class SleepService < Async::Service::Generic
-	def setup(container)
-		super
-		
-		container.run(count: 1, restart: true) do |instance|
-			# Use log level:
-			Console.logger.level = @environment.evaluator.log_level
-			
-			if container.statistics.failed?
-				Console.debug(self, "Child process restarted #{container.statistics.restarts} times.")
-			else
-				Console.debug(self, "Child process started.")
-			end
-
-			instance.ready!
-
-			while true
-				sleep 1
-
-				Console.debug(self, "Work")
-
-				if rand < 0.1
-					Console.debug(self, "Should exit...")
-					sleep 0.5
-					exit(1)
-				end
-			end
-		end
-	end	
-end
+require "async/service/sleep_service"
 
 service "sleep" do
 	include LogLevel
 
 	authority {self.name}
 	middleware {Object.new}
 
-	service_class SleepService
+	service_class Async::Service::SleepService
 end
 
 # A 2nd service:

test/async/service/configuration.rb

@@ -4,6 +4,7 @@
 # Copyright, 2024, by Samuel Williams.
 
 require 'async/service/configuration'
+require "async/service/good_interface"
 
 describe Async::Service::Configuration do
 	with '.build' do
@@ -29,6 +30,42 @@
 		end
 	end
 
+	with "null serice configuration file" do
+		let(:configuration_path) {File.join(__dir__, '.configurations', 'null.rb')}
+		
+		let(:configuration) do
+			subject.new.tap do |configuration|
+				configuration.load_file(configuration_path)
+			end
+		end
+		
+		it 'can load configuration' do
+			expect(configuration).not.to be(:empty?)
+			
+			environment = configuration.environments.first
+			evaluator = environment.evaluator
+			expect(evaluator.name).to be == 'null'
+			
+			expect(configuration.services.to_a).to be(:empty?)
+		end
+	end
+	
+	with "implementing service configuration file" do
+		let(:configuration_path) {File.join(__dir__, '.configurations', 'implementing.rb')}
+		
+		let(:configuration) do
+			subject.new.tap do |configuration|
+				configuration.load_file(configuration_path)
+			end
+		end
+		
+		it "can select services by implementing module" do
+			expect(configuration).not.to be(:empty?)
+			
+			expect(configuration.services(implementing: Async::Service::GoodInterface).to_a).not.to be(:empty?)
+		end
+	end
+	
 	with 'sleep service configuration file' do
 		let(:configuration_path) {File.join(__dir__, '.configurations', 'sleep.rb')}
 		let(:configuration_root) {File.join(File.realpath(__dir__), '.configurations')}