Add NumberItem#range

Returns a Range from and stated description, and applies units if possible

Signed-off-by: Cody Cutrer <cody@cutrer.us>

lib/openhab/core/items/number_item.rb

@@ -53,6 +53,30 @@ def config_eql?(other)
           super && dimension == other.dimension
         end
 
+        # @!attribute [r] range
+        # Returns the range of values allowed for this item, as defined by its
+        # state description.
+        #
+        # If this item has a {#unit}, it will be applied to the result, returning
+        # a range of {QuantityType} instead of BigDecimal.
+        # @return [Range]
+        # @note State descriptions can be provided by bindings, defined in
+        #   metadata, or theoretically come from other sources.
+        def range
+          return unless (sd = state_description)
+
+          # check if we have a unit, even if the item's metadata doesn't declare
+          # it properly
+          unit = self.unit || ((s = state) && s.is_a?(QuantityType) && s.unit)
+          min = sd.minimum&.to_d
+          max = sd.maximum&.to_d
+          return nil unless min || max
+
+          min |= unit if min && unit
+          max |= unit if max && unit
+          min..max
+        end
+
         protected
 
         # Adds the unit dimension

spec/openhab/core/items/number_item_spec.rb

@@ -7,7 +7,10 @@
     items.build do
       group_item "Numbers" do
         number_item "NumberOne", state: 0
-        number_item "NumberTwo", state: 70
+        number_item "NumberTwo", state: 70, format: "%s"
+        number_item "RangedNumber", range: 50..100
+        number_item "UnittedRangedNumber", range: 2700..6000, unit: "K"
+        number_item "OpenEndedNumber", range: 50.., unit: "°C"
       end
       number_item "NumberNull"
     end
@@ -23,7 +26,12 @@
 
   it "works with grep" do
     items.build { switch_item "Switch1" }
-    expect(items.grep(NumberItem)).to match_array [NumberOne, NumberTwo, NumberNull]
+    expect(items.grep(NumberItem)).to match_array [NumberOne,
+                                                   NumberTwo,
+                                                   NumberNull,
+                                                   RangedNumber,
+                                                   UnittedRangedNumber,
+                                                   OpenEndedNumber]
   end
 
   describe "#positive?" do
@@ -41,4 +49,25 @@
     end
     expect(Feet.state).to eq(6 | "ft")
   end
+
+  describe "#range?" do
+    it "returns nil without a meaningful state description" do
+      expect(NumberOne.range).to be_nil
+      expect(NumberTwo.range).to be_nil
+    end
+
+    it "returns a value with a state description" do
+      expect(RangedNumber.range).to eql 50..100
+    end
+
+    it "returns a QuantityType as necessary" do
+      UnittedRangedNumber.update(3000 | "K")
+      expect(UnittedRangedNumber.range).to eql(2700 | "K")..(6000 | "K")
+    end
+
+    it "supports open ended ranges" do
+      OpenEndedNumber.update(75 | "°C")
+      expect(OpenEndedNumber.range).to eql(50 | "°C")..
+    end
+  end
 end