Index: Ringtoets/StabilityStoneCover/test/Ringtoets.StabilityStoneCover.Integration.Test/StabilityStoneCoverWaveConditionsCalculationActivityIntegrationTest.cs
===================================================================
diff -u -r73114a1d1b9584c215af6cf47aa309d80cda16a4 -r26bd14a3e6900dd265bdea580e9c6f342593d9ef
--- Ringtoets/StabilityStoneCover/test/Ringtoets.StabilityStoneCover.Integration.Test/StabilityStoneCoverWaveConditionsCalculationActivityIntegrationTest.cs	(.../StabilityStoneCoverWaveConditionsCalculationActivityIntegrationTest.cs)	(revision 73114a1d1b9584c215af6cf47aa309d80cda16a4)
+++ Ringtoets/StabilityStoneCover/test/Ringtoets.StabilityStoneCover.Integration.Test/StabilityStoneCoverWaveConditionsCalculationActivityIntegrationTest.cs	(.../StabilityStoneCoverWaveConditionsCalculationActivityIntegrationTest.cs)	(revision 26bd14a3e6900dd265bdea580e9c6f342593d9ef)
@@ -714,15 +714,16 @@
             mockRepository.ReplayAll();
 
             IAssessmentSection assessmentSection = CreateAssessmentSectionWithHydraulicBoundaryOutput();
-            var failureMechanism = new StabilityStoneCoverFailureMechanism();
 
             StabilityStoneCoverWaveConditionsCalculation calculation = CreateValidCalculation(assessmentSection.HydraulicBoundaryDatabase.Locations.First());
 
             calculation.Attach(observer);
 
-            CalculatableActivity activity = StabilityStoneCoverWaveConditionsCalculationActivityFactory.CreateCalculationActivity(calculation,
-                                                                                                                                  failureMechanism,
-                                                                                                                                  assessmentSection);
+            CalculatableActivity activity = StabilityStoneCoverWaveConditionsCalculationActivityFactory.CreateCalculationActivity(
+                calculation,
+                new StabilityStoneCoverFailureMechanism(),
+                assessmentSection);
+
             using (new HydraRingCalculatorFactoryConfig(calculatorFactory))
             {
                 activity.Run();
@@ -753,15 +754,16 @@
             mockRepository.ReplayAll();
 
             IAssessmentSection assessmentSection = CreateAssessmentSectionWithHydraulicBoundaryOutput();
-            var failureMechanism = new StabilityStoneCoverFailureMechanism();
 
             StabilityStoneCoverWaveConditionsCalculation calculation = CreateValidCalculation(assessmentSection.HydraulicBoundaryDatabase.Locations.First());
 
             calculation.Attach(observer);
 
-            CalculatableActivity activity = StabilityStoneCoverWaveConditionsCalculationActivityFactory.CreateCalculationActivity(calculation,
-                                                                                                                                  failureMechanism,
-                                                                                                                                  assessmentSection);
+            CalculatableActivity activity = StabilityStoneCoverWaveConditionsCalculationActivityFactory.CreateCalculationActivity(
+                calculation,
+                new StabilityStoneCoverFailureMechanism(),
+                assessmentSection);
+
             using (new HydraRingCalculatorFactoryConfig(calculatorFactory))
             {
                 activity.Run();
Index: Ringtoets/WaveImpactAsphaltCover/src/Ringtoets.WaveImpactAsphaltCover.Plugin/WaveImpactAsphaltCoverPlugin.cs
===================================================================
diff -u -r5ef2f44bca31b92735dff724f97b717c7c55f912 -r26bd14a3e6900dd265bdea580e9c6f342593d9ef
--- Ringtoets/WaveImpactAsphaltCover/src/Ringtoets.WaveImpactAsphaltCover.Plugin/WaveImpactAsphaltCoverPlugin.cs	(.../WaveImpactAsphaltCoverPlugin.cs)	(revision 5ef2f44bca31b92735dff724f97b717c7c55f912)
+++ Ringtoets/WaveImpactAsphaltCover/src/Ringtoets.WaveImpactAsphaltCover.Plugin/WaveImpactAsphaltCoverPlugin.cs	(.../WaveImpactAsphaltCoverPlugin.cs)	(revision 26bd14a3e6900dd265bdea580e9c6f342593d9ef)
@@ -566,11 +566,6 @@
                                                                                                        failureMechanism,
                                                                                                        assessmentSection))
                     .ToList());
-
-            foreach (WaveImpactAsphaltCoverWaveConditionsCalculation calculation in calculations)
-            {
-                calculation.NotifyObservers();
-            }
         }
 
         private static void WaveConditionsCalculationGroupContextOnNodeRemoved(WaveImpactAsphaltCoverWaveConditionsCalculationGroupContext nodeData, object parentNodeData)
@@ -664,7 +659,6 @@
                                                                                                          context.AssessmentSection.HydraulicBoundaryDatabase.FilePath,
                                                                                                          context.FailureMechanism,
                                                                                                          context.AssessmentSection));
-            calculation.NotifyObservers();
         }
 
         private static void WaveConditionsCalculationContextOnNodeRemoved(WaveImpactAsphaltCoverWaveConditionsCalculationContext nodeData, object parentNodeData)
Index: Ringtoets/WaveImpactAsphaltCover/src/Ringtoets.WaveImpactAsphaltCover.Service/WaveImpactAsphaltCoverWaveConditionsCalculationActivity.cs
===================================================================
diff -u -ra494bde768f1b989d31bff6a801a1816d6f9692e -r26bd14a3e6900dd265bdea580e9c6f342593d9ef
--- Ringtoets/WaveImpactAsphaltCover/src/Ringtoets.WaveImpactAsphaltCover.Service/WaveImpactAsphaltCoverWaveConditionsCalculationActivity.cs	(.../WaveImpactAsphaltCoverWaveConditionsCalculationActivity.cs)	(revision a494bde768f1b989d31bff6a801a1816d6f9692e)
+++ Ringtoets/WaveImpactAsphaltCover/src/Ringtoets.WaveImpactAsphaltCover.Service/WaveImpactAsphaltCoverWaveConditionsCalculationActivity.cs	(.../WaveImpactAsphaltCoverWaveConditionsCalculationActivity.cs)	(revision 26bd14a3e6900dd265bdea580e9c6f342593d9ef)
@@ -104,7 +104,7 @@
 
         protected override void OnFinish()
         {
-            // something.Notify();
+            calculation.NotifyObservers();
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/WaveImpactAsphaltCover/test/Ringtoets.WaveImpactAsphaltCover.Integration.Test/WaveImpactAsphaltCoverWaveConditionsCalculationActivityIntegrationTest.cs
===================================================================
diff -u -r3370d752e150391d16ebfb96533921d777f4580c -r26bd14a3e6900dd265bdea580e9c6f342593d9ef
--- Ringtoets/WaveImpactAsphaltCover/test/Ringtoets.WaveImpactAsphaltCover.Integration.Test/WaveImpactAsphaltCoverWaveConditionsCalculationActivityIntegrationTest.cs	(.../WaveImpactAsphaltCoverWaveConditionsCalculationActivityIntegrationTest.cs)	(revision 3370d752e150391d16ebfb96533921d777f4580c)
+++ Ringtoets/WaveImpactAsphaltCover/test/Ringtoets.WaveImpactAsphaltCover.Integration.Test/WaveImpactAsphaltCoverWaveConditionsCalculationActivityIntegrationTest.cs	(.../WaveImpactAsphaltCoverWaveConditionsCalculationActivityIntegrationTest.cs)	(revision 26bd14a3e6900dd265bdea580e9c6f342593d9ef)
@@ -23,6 +23,7 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using Core.Common.Base;
 using Core.Common.Base.Data;
 using Core.Common.Base.Service;
 using Core.Common.TestUtil;
@@ -32,6 +33,7 @@
 using Ringtoets.Common.Data.DikeProfiles;
 using Ringtoets.Common.Data.Hydraulics;
 using Ringtoets.Common.Data.TestUtil;
+using Ringtoets.Common.Service;
 using Ringtoets.Common.Service.TestUtil;
 using Ringtoets.HydraRing.Calculation.Calculator.Factory;
 using Ringtoets.HydraRing.Calculation.Data;
@@ -532,6 +534,98 @@
             mockRepository.VerifyAll();
         }
 
+        [Test]
+        [TestCaseSource(typeof(HydraRingCalculatorTestCaseProvider), nameof(HydraRingCalculatorTestCaseProvider.GetCalculatorFailingConditions), new object[]
+        {
+            nameof(Finish_InvalidCalculation_DoesNotSetOutputAndNotifyObservers)
+        })]
+        public void Finish_InvalidCalculation_DoesNotSetOutputAndNotifyObservers(bool endInFailure,
+                                                                                 string lastErrorFileContent)
+        {
+            // Setup
+            var mockRepository = new MockRepository();
+            var observer = mockRepository.StrictMock<IObserver>();
+            observer.Expect(o => o.UpdateObserver());
+
+            var calculator = new TestWaveConditionsCosineCalculator
+            {
+                EndInFailure = endInFailure,
+                LastErrorFileContent = lastErrorFileContent
+            };
+            var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
+            calculatorFactory.Expect(cf => cf.CreateWaveConditionsCosineCalculator(testDataPath, string.Empty)).Return(calculator).Repeat.Times(3);
+            mockRepository.ReplayAll();
+
+            IAssessmentSection assessmentSection = CreateAssessmentSectionWithHydraulicBoundaryOutput();
+
+            WaveImpactAsphaltCoverWaveConditionsCalculation calculation = CreateValidCalculation(assessmentSection.HydraulicBoundaryDatabase.Locations.First());
+
+            calculation.Attach(observer);
+
+            CalculatableActivity activity = WaveImpactAsphaltCoverWaveConditionsCalculationActivityFactory.CreateCalculationActivity(
+                calculation,
+                new WaveImpactAsphaltCoverFailureMechanism(),
+                assessmentSection);
+
+            using (new HydraRingCalculatorFactoryConfig(calculatorFactory))
+            {
+                activity.Run();
+            }
+
+            // Call
+            activity.Finish();
+
+            // Assert
+            Assert.IsNull(calculation.Output);
+            mockRepository.VerifyAll();
+        }
+
+        [Test]
+        public void Finish_ValidCalculation_SetsOutputAndNotifyObserversOfCalculation()
+        {
+            // Setup
+            var mockRepository = new MockRepository();
+            var observer = mockRepository.StrictMock<IObserver>();
+            observer.Expect(o => o.UpdateObserver());
+
+            var calculatorFactory = mockRepository.StrictMock<IHydraRingCalculatorFactory>();
+            var waveConditionsCosineCalculator = new TestWaveConditionsCosineCalculator
+            {
+                WaveHeight = new Random(39).NextDouble()
+            };
+            calculatorFactory.Expect(cf => cf.CreateWaveConditionsCosineCalculator(testDataPath, string.Empty)).Return(waveConditionsCosineCalculator).Repeat.Times(3);
+            mockRepository.ReplayAll();
+
+            IAssessmentSection assessmentSection = CreateAssessmentSectionWithHydraulicBoundaryOutput();
+
+            WaveImpactAsphaltCoverWaveConditionsCalculation calculation = CreateValidCalculation(assessmentSection.HydraulicBoundaryDatabase.Locations.First());
+
+            calculation.Attach(observer);
+
+            CalculatableActivity activity = WaveImpactAsphaltCoverWaveConditionsCalculationActivityFactory.CreateCalculationActivity(
+                calculation,
+                new WaveImpactAsphaltCoverFailureMechanism(),
+                assessmentSection);
+
+            using (new HydraRingCalculatorFactoryConfig(calculatorFactory))
+            {
+                activity.Run();
+            }
+
+            // Call
+            activity.Finish();
+
+            // Assert
+            Assert.IsNotNull(calculation.Output);
+            Assert.AreEqual(3, calculation.Output.Items.Count());
+            foreach (WaveConditionsOutput waveConditionsOutput in calculation.Output.Items)
+            {
+                Assert.AreEqual(waveConditionsCosineCalculator.WaveHeight, waveConditionsOutput.WaveHeight, waveConditionsOutput.WaveHeight.GetAccuracy());
+            }
+
+            mockRepository.VerifyAll();
+        }
+
         private static WaveImpactAsphaltCoverWaveConditionsCalculation CreateValidCalculation(HydraulicBoundaryLocation hydraulicBoundaryLocation)
         {
             return new WaveImpactAsphaltCoverWaveConditionsCalculation