Merge pull request #186 from marklam/Int64

Proposed fix for issue #185

src/Hedgehog/Range.fs

@@ -122,7 +122,7 @@ module Range =
             fromBigInt (z + diff)
 
         /// Scale an integral exponentially with the size parameter.
-        let inline scaleExponential (sz0 : Size) (z0 : 'a) (n0 : 'a) : 'a =
+        let inline scaleExponential (lo : 'a) (hi : 'a) (sz0 : Size) (z0 : 'a) (n0 : 'a) : 'a =
             let sz =
                 clamp 0 99 sz0
 
@@ -135,7 +135,8 @@ module Range =
             let diff =
                  (((float (abs (n - z) + 1I)) ** (float sz / 99.0)) - 1.0) * float (sign (n - z))
 
-            fromBigInt (bigint (round (float z + diff)))
+            // https://github.com/hedgehogqa/fsharp-hedgehog/issues/185
+            fromBigInt (clamp (toBigInt lo) (toBigInt hi) (bigint (round (float z + diff))))
 
     /// Construct a range which scales the bounds relative to the size
     /// parameter.
@@ -173,10 +174,13 @@ module Range =
     [<CompiledName("ExponentialFrom")>]
     let inline exponentialFrom (z : 'a) (x : 'a) (y : 'a) : Range<'a> =
         Range (z, fun sz ->
+            let scale =
+                // https://github.com/hedgehogqa/fsharp-hedgehog/issues/185
+                scaleExponential x y sz z
             let x_sized =
-                clamp x y (scaleExponential sz z x)
+                scale x
             let y_sized =
-                clamp x y (scaleExponential sz z y)
+                scale y
             x_sized, y_sized)
 
     /// Construct a range which scales the second bound exponentially relative

tests/Hedgehog.Tests/GenTests.fs

@@ -1,6 +1,5 @@
 module Hedgehog.Tests.GenTests
 
-open System
 open Hedgehog
 open Swensen.Unquote
 open Xunit
@@ -66,13 +65,15 @@ let ``dateTime shrinks to correct mid-value`` () =
     System.DateTime (2000, 1, 1) =! result
 
 [<Fact>]
-let ``uint64 doesn't return any out-of-range value`` () =
-    let gen = Gen.uint64 <| Range.constant 1UL UInt64.MaxValue
-    let actual = Gen.sample 0 100 gen
-    test <@ actual |> List.contains 0UL |> not @>
+let ``int64 can create exponentially bounded integer`` () =
+    Property.check <| property {
+        let! _ = Gen.int64 (Range.exponentialBounded ())
+        return true
+    }
 
 [<Fact>]
-let ``uint32 doesn't return any out-of-range value`` () =
-    let gen = Gen.uint32 <| Range.constant 1ul UInt32.MaxValue
-    let actual = Gen.sample 0 100 gen
-    test <@ actual |> List.contains 0ul |> not @>
+let ``uint64 can create exponentially bounded integer`` () =
+    Property.check <| property {
+        let! _ = Gen.uint64 (Range.exponentialBounded ())
+        return true
+    }