Merge pull request #38 from winglian/feature/lbf-to-newton

#29 convert pound-force/lbf to newtons

Author: cannawen

src/conversion_helper.js

@@ -77,6 +77,7 @@ const metricDistanceUnits = [/km/, /light-?years?/,
                              /(?:milli|centi|deca|kilo)?met(?:re|er)s?/];
 const metricWeightUnits = [/kgs?/, /grams?/, /kilograms?/];
 const metricVolumeUnits = [/(?:milli|centi|deca|kilo)?lit(?:er|re)s?/, /(?:deca|kilo)?m(?:eters?)?(?:\^3| cubed?)/];
+const metricForceUnits = [/newtons?/, /dynes?/];
 
 const ukSubreddits = ["britain", "british", "england", "english", "scotland", "scottish", "wales", "welsh", "ireland", "irish", "london", "uk"];
 
@@ -264,6 +265,14 @@ const unitLookupList = [
     "conversionFunction" : (i) => distanceMap(i * 201.168),
     "ignoredUnits" : metricDistanceUnits
   },
+  {
+    "imperialUnits" : [/pounds?[ -]?(?:force)/, /lbf/, /lbs?[ -]?(?:force)/],
+    "standardInputUnit" : " lbf",
+    "isInvalidInput" : isZeroOrNegative,
+    "isWeaklyInvalidInput" : isHyperbole,
+    "conversionFunction" : (i) => createMap(i * 4.44822, " N"),
+    "ignoredUnits" : metricForceUnits
+  },
   {
     "imperialUnits" : "lbs?",
     "weakImperialUnits" : [/pounds?/],

test/converter-test.js

@@ -346,6 +346,37 @@ describe('Converter', () => {
       }) 
     })
 
+    context('lbf', () => {
+      it('should convert', () => {
+        testConvert(
+          [
+            "1 lbf",
+            "2 lbf",
+            "0.1 pound-force",
+            "0.2 pounds-force",
+            "10 pound force",
+            "20 pounds force",
+            "3 lb force",
+            "4 lbs force",
+            "5 lb-force",
+            "6 lbs-force"
+          ],
+          {
+            "1 lbf" : "4.4 N",
+            "2 lbf" : "9 N",
+            "0.1 lbf" : "0.4 N",
+            "0.2 lbf" : "0.9 N",
+            "10 lbf" : "44 N",
+            "20 lbf" : "90 N",
+            "3 lbf" : "13 N",
+            "4 lbf" : "18 N",
+            "5 lbf" : "22 N",
+            "6 lbf" : "27 N"
+          }
+        );
+      });
+    });
+
     context('supported special characters', () => {
       it('should convert when starting with special characters', () => {
         testConvert(