add unit test to check LoadingTestArea has what it needs for the property tests.

TestCentre/LibraryTests.fs

@@ -61,4 +61,18 @@
         [<Property>]
         let ``Can populate the LoadingTestArea`` () =
             populateLoadingTestArea ()
-            true = true
+            true = true
+
+    module UnitTests =
+
+        open System.IO
+        open TestingHelpers
+        open Xunit
+
+        // This test is just a check to make sure the property tests have what they need to run.
+        [<Fact>]
+        let ``LoadingTestArea contains at least 100 test images`` () =
+            let files = Directory.GetFileSystemEntries (loadLocation, "*.png")
+            let length = files.Length
+            let result = if length < 100 then false else true
+            Assert.True result