Added new units tn, LT, hyl, cwt, and cwt (US) in weight

lib/unit_measurements/unit_groups/weight.rb

@@ -24,11 +24,22 @@
     unit "oz", value: "1/16 lb", aliases: ["ounce", "ounces"]
     unit "dr", value: "1/16 oz", aliases: ["dram", "drams"]
     unit "gr", value: "1/7000 lb", aliases: ["grain", "grains"]
+    unit "LT", value: "2240 lb", aliases: ["imperial ton", "displacement ton", "imperial tons", "displacement tons", "long ton", "long tons", "weight ton", "weight tons"]
 
     unit "drt", value: "60 gr", aliases: ["troy dram", "troy drams"]
     unit "ozt", value: "480 gr", aliases: ["troy ounce", "troy ounces"]
     unit "lbt", value: "5760 gr", aliases: ["troy pound", "troy pounds"]
     unit "dwt", value: "1/20 ozt", aliases: ["pwt", "pennyweight", "pennyweights"]
+    unit "cwt", value: "112 lb", aliases: ["hundredweight", "long hundredweight", "imperial hundredweight"]
+  end
+
+  system :us_customary do
+    unit "tn", value: "2000 lb", aliases: ["ton", "tons", "short ton", "short tons"]
+    unit "cwt (US)", value: "100 lb", aliases: ["hundredweight (US)", "short hundredweight"]
+  end
+
+  system :gravitational_metric do
+    unit "hyl", value: "9.80665 kg", aliases: ["mug", "metric slug", "metric slugs", "hyls"]
   end
 
   system :foot_pound_second do

spec/unit_measurements/unit_groups/weight_spec.rb

@@ -52,6 +52,14 @@
       expect(subject.convert_to("dr").quantity).to eq(2.82191695596643)
     end
 
+    it "converts to tn" do
+      expect(subject.convert_to("tn").quantity).to eq(5.51155655462194e-6)
+    end
+
+    it "converts to LT" do
+      expect(subject.convert_to("LT").quantity).to eq(4.9210326380553e-6)
+    end
+
     it "converts to ozt" do
       expect(subject.convert_to("ozt").quantity).to eq(0.16075373284314)
     end
@@ -68,8 +76,20 @@
       expect(subject.convert_to("lbt").quantity).to eq(0.013396144403595)
     end
 
+    it "converts to hyl" do
+      expect(subject.convert_to("hyl").quantity).to eq(0.000509858106488964)
+    end
+
+    it "converts to cwt" do
+      expect(subject.convert_to("cwt").quantity).to eq(0.0000984206527611061)
+    end
+
     it "converts to slug" do
       expect(subject.convert_to("slug").quantity).to eq(0.000342608829245948)
     end
+
+    it "converts to cwt (US)" do
+      expect(subject.convert_to("cwt (US)").quantity).to eq(0.000110231131092439)
+    end
   end
 end