Index: Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Forms.Test/TreeNodeInfos/GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs
===================================================================
diff -u -rdf02e9274a94d8763da204833a4d93f984e242c6 -r9598b5ccb274c8aedd4d0407ef3120d82935d3fe
--- Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Forms.Test/TreeNodeInfos/GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs	(.../GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs)	(revision df02e9274a94d8763da204833a4d93f984e242c6)
+++ Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Forms.Test/TreeNodeInfos/GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs	(.../GrassCoverErosionInwardsCalculationContextTreeNodeInfoTest.cs)	(revision 9598b5ccb274c8aedd4d0407ef3120d82935d3fe)
@@ -571,12 +571,13 @@
         }
 
         [Test]
-        public void GivenCalculationWithNonExistingFilePath_WhenCalculatingFromContextMenu_ThenOutputClearedLogMessagesAddedObserversNotNotified()
+        public void GivenCalculationWithNonExistingFilePath_WhenCalculatingFromContextMenu_ThenOutputClearedLogMessagesAddedAndUpdateObserver()
         {
             // Given
             var gui = mocks.DynamicMock<IGui>();
             var mainWindow = mocks.DynamicMock<IMainWindow>();
             var observerMock = mocks.StrictMock<IObserver>();
+            observerMock.Expect(o => o.UpdateObserver());
 
             var section = new FailureMechanismSection("A", new[]
             {
Index: Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Integration.Test/GrassCoverErosionInwardsCalculationActivityIntegrationTest.cs
===================================================================
diff -u -rfef3460a27a37aaa34948649aae3dd9ae143041c -r9598b5ccb274c8aedd4d0407ef3120d82935d3fe
--- Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Integration.Test/GrassCoverErosionInwardsCalculationActivityIntegrationTest.cs	(.../GrassCoverErosionInwardsCalculationActivityIntegrationTest.cs)	(revision fef3460a27a37aaa34948649aae3dd9ae143041c)
+++ Ringtoets/GrassCoverErosionInwards/test/Ringtoets.GrassCoverErosionInwards.Integration.Test/GrassCoverErosionInwardsCalculationActivityIntegrationTest.cs	(.../GrassCoverErosionInwardsCalculationActivityIntegrationTest.cs)	(revision 9598b5ccb274c8aedd4d0407ef3120d82935d3fe)
@@ -299,11 +299,12 @@
         }
 
         [Test]
-        public void Finish_InvalidGrassCoverErosionInwardsCalculationAndRan_DoesNotSetOutputAndDoesNotNotifyObserversOfGrassCoverErosionInwardsCalculation()
+        public void Finish_InvalidGrassCoverErosionInwardsCalculationAndRan_DoesNotSetOutputAndNotifyObserversOfGrassCoverErosionInwardsCalculation()
         {
             // Setup
             var mocks = new MockRepository();
             var observerMock = mocks.StrictMock<IObserver>();
+            observerMock.Expect(o => o.UpdateObserver());
             mocks.ReplayAll();
 
             var assessmentSection = new AssessmentSection(AssessmentSectionComposition.Dike);
Index: Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Forms.Test/TreeNodeInfos/HeightStructuresCalculationContextTreeNodeInfoTest.cs
===================================================================
diff -u -r94a8fd834622a76d6f5923d1dd6dddf3601e76ea -r9598b5ccb274c8aedd4d0407ef3120d82935d3fe
--- Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Forms.Test/TreeNodeInfos/HeightStructuresCalculationContextTreeNodeInfoTest.cs	(.../HeightStructuresCalculationContextTreeNodeInfoTest.cs)	(revision 94a8fd834622a76d6f5923d1dd6dddf3601e76ea)
+++ Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Forms.Test/TreeNodeInfos/HeightStructuresCalculationContextTreeNodeInfoTest.cs	(.../HeightStructuresCalculationContextTreeNodeInfoTest.cs)	(revision 9598b5ccb274c8aedd4d0407ef3120d82935d3fe)
@@ -566,12 +566,13 @@
         }
 
         [Test]
-        public void GivenCalculationWithNonExistingFilePath_WhenCalculatingFromContextMenu_ThenOutputClearedLogMessagesAddedObserversNotNotified()
+        public void GivenCalculationWithNonExistingFilePath_WhenCalculatingFromContextMenu_ThenOutputClearedLogMessagesAddedAndUpdateObserver()
         {
             // Given
             var gui = mocks.DynamicMock<IGui>();
             var mainWindow = mocks.DynamicMock<IMainWindow>();
             var observerMock = mocks.StrictMock<IObserver>();
+            observerMock.Expect(o => o.UpdateObserver());
 
             var section = new FailureMechanismSection("A", new[]
             {
Index: Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Integration.Test/HeightStructuresCalculationActivityIntegrationTest.cs
===================================================================
diff -u -r0f7eb2998561112d0013b667ee39c2316341d2fe -r9598b5ccb274c8aedd4d0407ef3120d82935d3fe
--- Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Integration.Test/HeightStructuresCalculationActivityIntegrationTest.cs	(.../HeightStructuresCalculationActivityIntegrationTest.cs)	(revision 0f7eb2998561112d0013b667ee39c2316341d2fe)
+++ Ringtoets/HeightStructures/test/Ringtoets.HeightStructures.Integration.Test/HeightStructuresCalculationActivityIntegrationTest.cs	(.../HeightStructuresCalculationActivityIntegrationTest.cs)	(revision 9598b5ccb274c8aedd4d0407ef3120d82935d3fe)
@@ -261,11 +261,12 @@
         }
 
         [Test]
-        public void Finish_InValidHeightStructuresCalculationAndRan_DoesNotSetOutputAndDoesNotNotifyObserversOfHeightStructuresCalculation()
+        public void Finish_InValidHeightStructuresCalculationAndRan_DoesNotSetOutputAndNotifyObserversOfHeightStructuresCalculation()
         {
             // Setup
             var mocks = new MockRepository();
             var observerMock = mocks.StrictMock<IObserver>();
+            observerMock.Expect(o => o.UpdateObserver());
             mocks.ReplayAll();
 
             var assessmentSection = new AssessmentSection(AssessmentSectionComposition.Dike);
Index: Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Activities/HydraRingActivity.cs
===================================================================
diff -u -r5e6eacaf76f765ba77febee673e9e94895e46feb -r9598b5ccb274c8aedd4d0407ef3120d82935d3fe
--- Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Activities/HydraRingActivity.cs	(.../HydraRingActivity.cs)	(revision 5e6eacaf76f765ba77febee673e9e94895e46feb)
+++ Ringtoets/HydraRing/src/Ringtoets.HydraRing.Calculation/Activities/HydraRingActivity.cs	(.../HydraRingActivity.cs)	(revision 9598b5ccb274c8aedd4d0407ef3120d82935d3fe)
@@ -74,7 +74,7 @@
         }
 
         /// <summary>
-        /// Method for performing the finish of the activity. If the calculation is successfull
+        /// Method for performing the finish of the activity. If the calculation is successful
         /// executed, the output will be set on the calculation. After that the observers of 
         /// <paramref name="observableObject"/> will be notified.
         /// </summary>
@@ -85,8 +85,8 @@
             if (State == ActivityState.Executed)
             {
                 setOutputAction();
-                observableObject.NotifyObservers();
             }
+            observableObject.NotifyObservers();
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Activities/HydraRingActivityTest.cs
===================================================================
diff -u -r5e6eacaf76f765ba77febee673e9e94895e46feb -r9598b5ccb274c8aedd4d0407ef3120d82935d3fe
--- Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Activities/HydraRingActivityTest.cs	(.../HydraRingActivityTest.cs)	(revision 5e6eacaf76f765ba77febee673e9e94895e46feb)
+++ Ringtoets/HydraRing/test/Ringtoets.HydraRing.Calculation.Test/Activities/HydraRingActivityTest.cs	(.../HydraRingActivityTest.cs)	(revision 9598b5ccb274c8aedd4d0407ef3120d82935d3fe)
@@ -110,17 +110,14 @@
         }
 
         [Test]
-        public void Finish_OutputNull_DoesNotSetOutputAndDoesNotNotifyObservers()
+        public void Finish_OutputNull_DoesNotSetOutputAndNotifyObservers()
         {
             // Setup
             var mocks = new MockRepository();
-            var observerMock = mocks.StrictMock<IObserver>();
             var observableMock = mocks.StrictMock<IObservable>();
-            observableMock.Expect(o => o.Attach(observerMock));
+            observableMock.Expect(o => o.NotifyObservers());
             mocks.ReplayAll();
 
-            observableMock.Attach(observerMock);
-
             TestHydraRingActivity activity = new TestHydraRingActivity(true, () => null, observableMock);
 
             activity.Run();
Index: Ringtoets/Integration/test/Ringtoets.Integration.Service.Test/DesignWaterLevelCalculationActivityTest.cs
===================================================================
diff -u -rc45538da49b7940b722e1f12b95d16beb4ee8206 -r9598b5ccb274c8aedd4d0407ef3120d82935d3fe
--- Ringtoets/Integration/test/Ringtoets.Integration.Service.Test/DesignWaterLevelCalculationActivityTest.cs	(.../DesignWaterLevelCalculationActivityTest.cs)	(revision c45538da49b7940b722e1f12b95d16beb4ee8206)
+++ Ringtoets/Integration/test/Ringtoets.Integration.Service.Test/DesignWaterLevelCalculationActivityTest.cs	(.../DesignWaterLevelCalculationActivityTest.cs)	(revision 9598b5ccb274c8aedd4d0407ef3120d82935d3fe)
@@ -203,11 +203,12 @@
         }
 
         [Test]
-        public void Finish_InvalidCalculationAndRun_DoesNotSetDesignWaterlevelAndDoesNotNotifyObservers()
+        public void Finish_InvalidCalculationAndRun_DoesNotSetDesignWaterlevelAndUpdateObserver()
         {
             // Setup
             var mocks = new MockRepository();
             var observerMock = mocks.StrictMock<IObserver>();
+            observerMock.Expect(o => o.UpdateObserver());
             mocks.ReplayAll();
 
             var assessmentSection = new AssessmentSection(AssessmentSectionComposition.Dike);