Support adding group members with GroupItem.members.add (#322)

Signed-off-by: Jimmy Tanagra <jcode@tanagra.id.au>

lib/openhab/core/items/group_item.rb

@@ -83,6 +83,26 @@ def initialize(group_item)
             @group = group_item
           end
 
+          #
+          # Adds a member to the group
+          #
+          # @param [Item, String] member The item to add to the group
+          # @return [Members] self
+          #
+          def add(member)
+            if member.is_a?(String)
+              member = items[member]
+              raise ArgumentError, "Item not found: #{member}" if member.nil?
+            end
+
+            member = member.__getobj__ if member.is_a?(Proxy)
+            raise ArgumentError, "Member must be an Item" unless member.is_a?(Item)
+
+            group.add_member(member)
+            self
+          end
+          alias_method :<<, :add
+
           # Explicit conversion to Array
           #
           # @return [Array]

spec/openhab/core/items/group_item_spec.rb

@@ -72,6 +72,18 @@
                                                                        Den_Temp,
                                                                        LivingRoom]
     end
+
+    describe "#add" do
+      it "can be used to add a new member" do
+        expect(Temperatures.members.count).to be 3
+        items.build do
+          number_item "Kitchen_Temp"
+        end
+        Temperatures.members.add Kitchen_Temp
+        expect(Temperatures.members.count).to be 4
+        expect(Temperatures.members).to include Kitchen_Temp
+      end
+    end
   end
 
   describe "#all_members" do