Merge pull request #166 from typelevel/stone

add stone mass unit

shared/src/main/scala/squants/mass/Mass.scala

@@ -48,6 +48,7 @@ final class Mass private (val value: Double, val unit: MassUnit)
   def toPounds = to(Pounds)
   def toKilopounds = to(Kilopounds)
   def toMegapounds = to(Megapounds)
+  def toStone = to(Stone)
   def toTroyGrains = to(TroyGrains)
   def toPennyweights = to(Pennyweights)
   def toTroyOunces = to(TroyOunces)
@@ -65,7 +66,7 @@ object Mass extends Dimension[Mass] with BaseDimension {
   def name = "Mass"
   def primaryUnit = Grams
   def siUnit = Kilograms
-  def units = Set(Micrograms, Milligrams, Grams, Kilograms, Tonnes, Ounces, Pounds, Kilopounds, Megapounds,
+  def units = Set(Micrograms, Milligrams, Grams, Kilograms, Tonnes, Ounces, Pounds, Kilopounds, Megapounds, Stone,
     TroyGrains, Pennyweights, TroyOunces, TroyPounds, Tolas, Carats)
   def dimensionSymbol = "M"
 }
@@ -121,6 +122,11 @@ object Megapounds extends MassUnit {
   val symbol = "Mlb"
 }
 
+object Stone extends MassUnit {
+  val conversionFactor = Pounds.conversionFactor * 14d
+  val symbol = "st"
+}
+
 object TroyGrains extends MassUnit {
   val conversionFactor = 64.79891 * Milligrams.conversionFactor
   val symbol = "gr"
@@ -166,6 +172,7 @@ object MassConversions {
   lazy val pound = Pounds(1)
   lazy val kilopound = Kilopounds(1)
   lazy val megapound = Megapounds(1)
+  lazy val stone = Stone(1)
   lazy val troyGrain = TroyGrains(1)
   lazy val pennyweight = Pennyweights(1)
   lazy val troyOunce = TroyOunces(1)
@@ -186,6 +193,7 @@ object MassConversions {
     def pounds = Pounds(n)
     def kilopounds = Kilopounds(n)
     def megapounds = Megapounds(n)
+    def stone = Stone(n)
     def troyGrains = TroyGrains(n)
     def dwt = Pennyweights(n)
     def pennyweights = Pennyweights(n)

shared/src/test/scala/squants/mass/MassSpec.scala

@@ -35,13 +35,13 @@ class MassSpec extends FlatSpec with Matchers {
     Pounds(10.22).toPounds should be(10.22)
     Kilopounds(10.22).toKilopounds should be(10.22)
     Megapounds(10.22).toMegapounds should be(10.22)
+    Stone(10.22).toStone should be(10.22)
     TroyGrains(10.22).toTroyGrains should be(10.22)
     Pennyweights(10.22).toPennyweights should be(10.22)
     TroyOunces(10.22).toTroyOunces should be(10.22)
     TroyPounds(10.22).toTroyPounds should be(10.22)
     Tolas(10.22).toTolas should be(10.22)
     Carats(10.22).toCarats should be(10.22)
-
   }
 
   it should "create values from properly formatted Strings" in {
@@ -54,6 +54,7 @@ class MassSpec extends FlatSpec with Matchers {
     Mass("10.22 lb").get should be(Pounds(10.22))
     Mass("10.22 klb").get should be(Kilopounds(10.22))
     Mass("10.22 Mlb").get should be(Megapounds(10.22))
+    Mass("10.22 st").get should be(Stone(10.22))
     Mass("10.22 gr").get should be(TroyGrains(10.22))
     Mass("10.22 dwt").get should be(Pennyweights(10.22))
     Mass("10.22 oz t").get should be(TroyOunces(10.22))
@@ -82,6 +83,7 @@ class MassSpec extends FlatSpec with Matchers {
     Grams(1000) should be(Kilograms(1))
     Kilograms(0.45359237) should be(Pounds(1))
     Ounces(16) should be(Pounds(1))
+    Pounds(14) should be(Stone(1))
 
     TroyOunces(12) should be(TroyPounds(1))
     TroyGrains(180) should be(Tolas(1))
@@ -100,6 +102,7 @@ class MassSpec extends FlatSpec with Matchers {
     Tonnes(1).toString(Tonnes) should be("1.0 t")
     Pounds(1).toString(Pounds) should be("1.0 lb")
     Ounces(1).toString(Ounces) should be("1.0 oz")
+    Stone(1).toString(Stone) should be("1.0 st")
 
     TroyGrains(1).toString(TroyGrains) should be("1.0 gr")
     Pennyweights(1).toString(Pennyweights) should be("1.0 dwt")
@@ -153,6 +156,7 @@ class MassSpec extends FlatSpec with Matchers {
     tonne should be(Tonnes(1))
     pound should be(Pounds(1))
     ounce should be(Ounces(1))
+    stone should be(Stone(1))
 
     troyGrain should be(TroyGrains(1))
     pennyweight should be(Pennyweights(1))
@@ -176,6 +180,7 @@ class MassSpec extends FlatSpec with Matchers {
     d.tonnes should be(Tonnes(d))
     d.pounds should be(Pounds(d))
     d.ounces should be(Ounces(d))
+    d.stone should be(Stone(d))
 
     d.troyGrains should be(TroyGrains(d))
     d.dwt should be(Pennyweights(d))
@@ -207,6 +212,7 @@ class MassSpec extends FlatSpec with Matchers {
     "10.45 t".toMass.get should be(Tonnes(10.45))
     "10.45 lb".toMass.get should be(Pounds(10.45))
     "10.45 oz".toMass.get should be(Ounces(10.45))
+    "10.45 st".toMass.get should be(Stone(10.45))
     "10.45 gr".toMass.get should be(TroyGrains(10.45))
     "10.45 dwt".toMass.get should be(Pennyweights(10.45))
     "10.45 oz t".toMass.get should be(TroyOunces(10.45))