Create property test for Array.blit

Author: forki

src/fsharp/FSharp.Core.Unittests/FSharp.Core/Microsoft.FSharp.Collections/ArrayProperties.fs

@@ -21,8 +21,10 @@ let ``Array.distinctBy is stable`` () =
     Check.QuickThrowOnFailure distinctByStable<string>
 
 let blitWorksLikeCopy<'a when 'a : comparison> (source : 'a [], sourceIndex, target : 'a [], targetIndex, count) =
-    let a = runAndCheckIfAnyError (fun () -> Array.blit source sourceIndex target targetIndex count)
-    let b = runAndCheckIfAnyError (fun () -> Array.Copy(source, sourceIndex, target, targetIndex, count))
+    let target1 = Array.copy target
+    let target2 = Array.copy target
+    let a = runAndCheckIfAnyError (fun () -> Array.blit source sourceIndex target1 targetIndex count)
+    let b = runAndCheckIfAnyError (fun () -> Array.Copy(source, sourceIndex, target2, targetIndex, count))
     a = b
 
 [<Test>]