TimeSeries: add #<< convenience method

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

lib/openhab/core/types/time_series.rb

@@ -122,6 +122,25 @@ def add(timestamp, state)
           self
         end
 
+        #
+        # Appends an entry to self, returns self
+        #
+        # @param [Array<Instant, State>] entry a two-element array with the timestamp and state.
+        #   The timestamp can be an {Instant} or any object that responds to #to_zoned_date_time.
+        # @return [self]
+        #
+        # @example Append an entry
+        #   time_series << [Time.at(2), 2]
+        #
+        def <<(entry)
+          raise ArgumentError, "entry must be an Array, but was #{entry.class}" unless entry.respond_to?(:to_ary)
+
+          entry = entry.to_ary
+          raise ArgumentError, "entry must be an Array of size 2, but was #{entry.size}" unless entry.size == 2
+
+          add(entry[0], entry[1])
+        end
+
         private
 
         def to_instant(timestamp)

spec/openhab/core/types/time_series_spec.rb

@@ -70,6 +70,17 @@
     end
   end
 
+  describe "#<<" do
+    it "works" do
+      ts << [Time.at(3), 3]
+      expect(ts.size).to be 3
+      expect(ts.first.state).to eql DecimalType.new(1)
+      expect(ts.begin).to eql Instant.of_epoch_second(1)
+      expect(ts.last.state).to eql DecimalType.new(3)
+      expect(ts.end).to eql Instant.of_epoch_second(3)
+    end
+  end
+
   context "when accessed as an Array" do
     it "is frozen" do
       expect(ts.states).to be_frozen