Fix Gen.choose for Double infinity

Author: ashawley

jvm/src/test/scala/org/scalacheck/GenSpecification.scala

@@ -121,6 +121,13 @@ object GenSpecification extends Properties("Gen") {
     MinValue <= x && x <= MaxValue
   }
 
+  import Double.{NegativeInfinity, PositiveInfinity}
+  property("choose-infinite-double") = {
+    Prop.forAllNoShrink(listOfN(3, choose(NegativeInfinity, PositiveInfinity))) { xs =>
+      xs.exists(_ != 0d)
+    }
+  }
+
   property("choose-xmap") = {
     implicit val chooseDate: Choose[Date] =
       Choose.xmap[Long, Date](new Date(_), _.getTime)

src/main/scala/org/scalacheck/Gen.scala

@@ -377,6 +377,10 @@ object Gen extends GenArities{
       val d = h - l
       if (d < 0) {
         throw new IllegalBoundsError(l, h)
+      } else if (l == Double.NegativeInfinity) {
+        chDbl(Double.MinValue, h)(p, seed)
+      } else if (h == Double.PositiveInfinity) {
+        chDbl(l, Double.MaxValue)(p, seed)
       } else if (d > Double.MaxValue) {
         val (x, seed2) = seed.long
         if (x < 0) chDbl(l, 0d)(p, seed2) else chDbl(0d, h)(p, seed2)