add full overlay image test to library tests.

TestCentre/LibraryTests.fs

@@ -10,6 +10,7 @@
         open SmoulderingBeachBall.Services
         open System.IO
         open System.Threading
+        open FsCheck
 
         (* '3000' is an arbitary value. It is used to keep the testing times sane.
         This function is used to randomly generate image sizes but you do not need to use it.
@@ -75,7 +76,7 @@
             fileSaved (spec.width.ToString()) (spec.height.ToString()) = true
 
         [<Property>]
-        let ``Can create image with border`` () =
+        let ``Can create an image with border`` () =
             resetSavingTestArea ()
             let spec =
                 { // See note accompanying 'randomInt' function for constraints information.
@@ -86,3 +87,16 @@
                   overlay = Some (buildBorderOverlay ()) }
             makeImage spec |> Async.RunSynchronously
             fileSaved (spec.width.ToString()) (spec.height.ToString()) = true
+
+        [<Property>]
+        let ``Can create an image with a full overlay`` () =
+            resetSavingTestArea ()
+            let spec =
+                { // See note accompanying 'randomInt' function for constraints information.
+                  width =  randomInt ()
+                  height = randomInt ()
+                  colour = randomColour () :?> Brush
+                  filePath = saveLocation
+                  overlay = Some (buildFullOverlay ()) }
+            makeImage spec |> Async.RunSynchronously
+            fileSaved (spec.width.ToString()) (spec.height.ToString()) = true