     }
     
     
-    func test_serialize_priority() throws {
+    func test_serialize_priority() {
         for (priority, jsonPriority) in [
             IncidentPriority.High  : 1,
             IncidentPriority.Normal: 3,
             IncidentPriority.Low   : 5,
         ] {
             let incident = Incident(number: 1, priority: priority)
-            let json = try incidentAsJSON(incident)
+
+            let json: IncidentDictionary
+            do { json = try incidentAsJSON(incident) }
+            catch { return XCTFail("\(error)") }
+            
             let expected: NSDictionary = [
                 "number": 1,
                 "priority": jsonPriority

            ]
        ]

        let incident = try incidentFromJSON(json)

        XCTAssertEqual(
            incident,

                Ranger(handle: "Splinter")
            ]
        )

        let json: IncidentDictionary
        do { json = try incidentAsJSON(incident) }
        catch { return XCTFail("\(error)") }
        
        let expected: NSDictionary = [
            "number": 1,
            "ranger_handles": [ "Splinter", "Tool" ]  // Should be sorted
