Merge pull request #382 from TysonMN/381_fix

Fix bug preventing rendering of reports containing None

Author: TysonMN

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## Version 0.12.0
 
 - Add Property.failOnFalse ([#380][380], [@TysonMN][TysonMN])
+- Fix bug [#381][381] that prevents rendering of reports containing `None` ([#382][382], [@TysonMN][TysonMN])
 
 ## Version 0.11.0 (2021-09-22)
 
@@ -175,6 +176,10 @@
 [porges]:
   https://github.com/porges
 
+[382]:
+  https://github.com/hedgehogqa/fsharp-hedgehog/pull/382
+[381]:
+  https://github.com/hedgehogqa/fsharp-hedgehog/pull/381
 [380]:
   https://github.com/hedgehogqa/fsharp-hedgehog/pull/380
 [363]:

src/Hedgehog/Property.fs

@@ -109,13 +109,16 @@ module Property =
         #if FABLE_COMPILER
             value
         #else
-            let t = value.GetType()
-            // have to use TypeInfo due to targeting netstandard 1.6
-            let t = System.Reflection.IntrospectionExtensions.GetTypeInfo(t)
-            let isList = t.IsGenericType && t.GetGenericTypeDefinition() = typedefof<ResizeArray<_>>
-            if isList
-            then value :?> System.Collections.IEnumerable |> Seq.cast<obj> |> List.ofSeq :> obj
-            else value
+            if value = null then
+                value
+            else
+                let t = value.GetType()
+                // have to use TypeInfo due to targeting netstandard 1.6
+                let t = System.Reflection.IntrospectionExtensions.GetTypeInfo(t)
+                let isList = t.IsGenericType && t.GetGenericTypeDefinition() = typedefof<ResizeArray<_>>
+                if isList
+                then value :?> System.Collections.IEnumerable |> Seq.cast<obj> |> List.ofSeq :> obj
+                else value
         #endif
 
         value |> prepareForPrinting |> sprintf "%A"

tests/Hedgehog.Tests/PropertyTests.fs

@@ -51,4 +51,13 @@ let propertyTests = testList "Property tests" [
 #else
         Expect.stringContains report guid "Missing counterexample text"
 #endif
+
+    testCase "Report containing None renders without throwing an exception" <| fun () ->
+        property {
+            let! opt = Gen.constant () |> Gen.option
+            return opt.IsSome
+        }
+        |> Property.report
+        |> Report.render
+        |> ignore
 ]