Index: Ringtoets/GrassCoverErosionOutwards/test/Ringtoets.GrassCoverErosionOutwards.Service.Test/GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs
===================================================================
diff -u -ra42bae106b7a5afd5ffb2a405c1265828a323588 -r8d2c93e2bc5f1993b9e8e9037f015e7d366ec636
--- Ringtoets/GrassCoverErosionOutwards/test/Ringtoets.GrassCoverErosionOutwards.Service.Test/GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs)	(revision a42bae106b7a5afd5ffb2a405c1265828a323588)
+++ Ringtoets/GrassCoverErosionOutwards/test/Ringtoets.GrassCoverErosionOutwards.Service.Test/GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs	(.../GrassCoverErosionOutwardsWaveConditionsCalculationServiceTest.cs)	(revision 8d2c93e2bc5f1993b9e8e9037f015e7d366ec636)
@@ -440,7 +440,7 @@
         }
 
         [Test]
-        public void Calculate_CanceledCalculationWithValidInput_CancelsCalculator()
+        public void Calculate_CanceledCalculationWithValidInput_CancelsCalculatorAndHasNullOutput()
         {
             // Setup
             GrassCoverErosionOutwardsWaveConditionsCalculation calculation = GetDefaultValidationInput();
@@ -454,15 +454,17 @@
             {
                 var testWaveConditionsCosineCalculator = ((TestHydraRingCalculatorFactory)HydraRingCalculatorFactory.Instance).WaveConditionsCosineCalculator;
                 var grassCoverErosionOutwardsWaveConditionsCalculationService = new GrassCoverErosionOutwardsWaveConditionsCalculationService();
+                testWaveConditionsCosineCalculator.CalculationFinishedHandler += (s, e) => grassCoverErosionOutwardsWaveConditionsCalculationService.Cancel();
 
+
                 // Call
                 grassCoverErosionOutwardsWaveConditionsCalculationService.Calculate(calculation,
                                                                                         grassCoverErosionOutwardsFailureMechanism,
                                                                                         assessmentSectionStub,
                                                                                         validFilePath);
-                grassCoverErosionOutwardsWaveConditionsCalculationService.Cancel();
 
                 // Assert
+                Assert.IsNull(calculation.Output);
                 Assert.IsTrue(testWaveConditionsCosineCalculator.IsCanceled);
             }
             mockRepository.VerifyAll();