Merge pull request #785 from yast/add-systemd-service-build

Add a SystemdService.build method

library/systemd/src/lib/yast2/system_service.rb

@@ -140,6 +140,16 @@ def find!(name)
         system_service
       end
 
+      # Builds a service instance based on the given name
+      #
+      # @param name [String] Service name
+      # @return [SystemService] System service based on the given name
+      #
+      # @see Yast::SystemdServiceClass#build
+      def build(name)
+        new(Yast::SystemdService.build(name))
+      end
+
       # Finds a set of services by their names
       #
       # @param names [Array<String>] service names to find
@@ -193,7 +203,8 @@ def substate
     #
     # @return [Symbol] :on_boot, :on_demand, :manual
     def current_start_mode
-      @current_start_mode ||=
+      return @current_start_mode unless @current_start_mode.nil?
+      @current_start_mode =
         if service.enabled?
           :on_boot
         elsif socket && socket.enabled?
@@ -251,11 +262,7 @@ def start_mode=(mode)
         raise ArgumentError, "Invalid start mode: '#{mode}' for service '#{service.name}'"
       end
 
-      if mode == current_start_mode
-        unregister_change(:start_mode)
-      else
-        register_change(:start_mode, mode)
-      end
+      register_change(:start_mode, mode)
     end
 
     # Whether the service supports :on_demand start mode
@@ -272,8 +279,8 @@ def support_start_on_demand?
     #
     # @return [Boolean] true if the service must be active; false otherwise
     def active?
-      return new_value_for(:active) if changed?(:active)
-      currently_active?
+      new_value = new_value_for(:active)
+      new_value.nil? ? currently_active? : new_value
     end
 
     # Keywords to search for this service
@@ -385,7 +392,7 @@ def refresh!
     #
     # @return [Boolean]
     def changed?(key = nil)
-      key ? changes.key?(key) : changes.any?
+      key ? changed_value?(key) : any_change?
     end
 
   private
@@ -406,16 +413,12 @@ def changed?(key = nil)
     #
     # @param value [Boolean] true to set this service as active
     def active=(value)
-      if value == currently_active?
-        unregister_change(:active)
-      else
-        register_change(:active, value)
-      end
+      register_change(:active, value)
     end
 
     # Sets start mode to the underlying system
     def save_start_mode
-      return unless changes[:start_mode]
+      return unless changed?(:start_mode)
 
       result =
         case changes[:start_mode]
@@ -540,13 +543,6 @@ def socket_active?
       socket.active?
     end
 
-    # Unregisters change for a given key
-    #
-    # @param key [Symbol] Change key
-    def unregister_change(key)
-      changes.delete(key)
-    end
-
     # Registers change for a given key
     #
     # @param key [Symbol] Change key
@@ -565,8 +561,30 @@ def clear_changes
     # @param key [Symbol] Change key
     # @return [Object] New value
     def new_value_for(key)
-      return nil unless changed?(key)
       changes[key]
     end
+
+    # Correspondence between changed values and methods to calculate their current value
+    CURRENT_VALUE_METHODS = {
+      active:     :currently_active?,
+      start_mode: :current_start_mode
+    }.freeze
+
+    # Determines whether a value has been changed
+    #
+    # @param key [Symbol] Changed value
+    # @return [Boolean] true if it has changed; false otherwise.
+    def changed_value?(key)
+      new_value = new_value_for(key)
+      return false if new_value.nil?
+      new_value != send(CURRENT_VALUE_METHODS[key])
+    end
+
+    # Determines whether some value has been changed
+    #
+    # @return [Boolean] true if it has changed; false otherwise.
+    def any_change?
+      CURRENT_VALUE_METHODS.keys.any? { |k| changed_value?(k) }
+    end
   end
 end

library/systemd/src/modules/systemd_service.rb

@@ -78,9 +78,7 @@ class SystemdServiceClass < Module
     # @param propmap [SystemdUnit::PropMap]
     # @return [Service,nil] `nil` if not found
     def find(service_name, propmap = {})
-      service_name += UNIT_SUFFIX unless service_name.end_with?(UNIT_SUFFIX)
-      propmap = SERVICE_PROPMAP.merge(propmap)
-      service = Service.new(service_name, propmap)
+      service = build(service_name, propmap)
       return nil if service.properties.not_found?
       service
     end
@@ -138,6 +136,20 @@ def all(propmap = {})
       end
     end
 
+    # Instantiate a SystemdService object based on the given name
+    #
+    # Use with caution as the service might exist or not. If you need to react when
+    # the service does not exist, use SystemdServiceClass.find.
+    #
+    # @param service_name [String] "foo" or "foo.service"
+    # @param propmap [SystemdUnit::PropMap]
+    # @return [Service] System service with the given name
+    def build(service_name, propmap = {})
+      service_name += UNIT_SUFFIX unless service_name.end_with?(UNIT_SUFFIX)
+      propmap = SERVICE_PROPMAP.merge(propmap)
+      Service.new(service_name, propmap)
+    end
+
     class Service < SystemdUnit
       include Yast::Logger
 

library/systemd/test/systemd_service_test.rb

@@ -22,10 +22,37 @@ module Yast
         end
       end
 
-      it "returns nil if the service unit does not exist" do
+      context "when the service does not exist" do
+        before do
+          properties = OpenStruct.new(
+            stdout: "", stderr: "Unit unknown.service could not be found.", exit: 1
+          )
+          allow_any_instance_of(Yast::SystemdUnit::Properties)
+            .to receive(:load_systemd_properties)
+            .and_return(properties)
+        end
+
+        it "returns nil" do
+          service = SystemdService.find("another")
+          expect(service).to be_nil
+        end
+      end
+    end
+
+    describe ".build" do
+      it "returns the service unit object specified in parameter" do
+        ["sshd", "sshd.service"].each do |service_name|
+          service = SystemdService.build(service_name)
+          expect(service).to be_a(SystemdUnit)
+          expect(service.unit_type).to eq("service")
+          expect(service.unit_name).to eq("sshd")
+        end
+      end
+
+      it "returns a service instance even if the real service does not exist" do
         stub_services(service: "unknown")
-        service = SystemdService.find("unknown")
-        expect(service).to be_nil
+        service = SystemdService.build("unknown")
+        expect(service.name).to eq("unknown")
       end
     end