Index: Ringtoets/Common/src/Ringtoets.Common.Forms/FailureMechanismPropertyChangeHandler.cs
===================================================================
diff -u -rd819ea1eaeed69d333b425c911c370397a24dc0f -ra1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501
--- Ringtoets/Common/src/Ringtoets.Common.Forms/FailureMechanismPropertyChangeHandler.cs	(.../FailureMechanismPropertyChangeHandler.cs)	(revision d819ea1eaeed69d333b425c911c370397a24dc0f)
+++ Ringtoets/Common/src/Ringtoets.Common.Forms/FailureMechanismPropertyChangeHandler.cs	(.../FailureMechanismPropertyChangeHandler.cs)	(revision a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501)
@@ -58,5 +58,55 @@
                 return Resources.FailureMechanismPropertyChangeHandler_Confirm_change_composition_and_clear_dependent_data;
             }
         }
+
+        /// <summary>
+        /// Find out whether the property can be updated with or without confirmation. If confirmation is required, 
+        /// the confirmation is obtained, after which the property is set if confirmation is given. If no confirmation
+        /// was required, then the value will be set for the property.
+        /// </summary>
+        /// <typeparam name="TValue">The type of the value that is set on a property of the failure mechanism.</typeparam>
+        /// <param name="failureMechanism">The failure mechanism for which the property is supposed to be set.</param>
+        /// <param name="value">The new value of the failure mechanism property.</param>
+        /// <param name="setValue">The operation which is performed to set the new property <paramref name="value"/>
+        /// on the <paramref name="failureMechanism"/>.</param>
+        /// <exception cref="ArgumentNullException">Thrown when any input parameter is <c>null</c>.</exception>
+        /// <remarks>Let <paramref name="setValue"/> throw an <see cref="Exception"/> when the 
+        /// <see cref="FailureMechanismPropertyChangeHandler{T}"/> should not process the results of that operation.</remarks>
+        public IEnumerable<IObservable> SetPropertyValueAfterConfirmation<TValue>(
+            T failureMechanism,
+            TValue value, SetFailureMechanismPropertyValueDelegate<T, TValue> setValue)
+        {
+            if (failureMechanism == null)
+            {
+                throw new ArgumentNullException(nameof(failureMechanism));
+            }
+            if (value == null)
+            {
+                throw new ArgumentNullException(nameof(value));
+            }
+            if (setValue == null)
+            {
+                throw new ArgumentNullException(nameof(setValue));
+            }
+
+            var changedObjects = new List<IObservable>();
+
+            if (RequiresConfirmation(failureMechanism))
+            {
+                if (ConfirmPropertyChange())
+                {
+                    setValue(failureMechanism, value);
+                    changedObjects.AddRange(PropertyChanged(failureMechanism));
+                    changedObjects.Add(failureMechanism);
+                }
+            }
+            else
+            {
+                setValue(failureMechanism, value);
+                changedObjects.Add(failureMechanism);
+            }
+
+            return changedObjects;
+        }
     }
 }
\ No newline at end of file
Fisheye: Tag a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501 refers to a dead (removed) revision in file `Ringtoets/Common/src/Ringtoets.Common.Forms/Helpers/IFailureMechanismPropertyChangeHandlerExtensions.cs'.
Fisheye: No comparison available.  Pass `N' to diff?
Index: Ringtoets/Common/src/Ringtoets.Common.Forms/PropertyClasses/IFailureMechanismPropertyChangeHandler.cs
===================================================================
diff -u -rd819ea1eaeed69d333b425c911c370397a24dc0f -ra1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501
--- Ringtoets/Common/src/Ringtoets.Common.Forms/PropertyClasses/IFailureMechanismPropertyChangeHandler.cs	(.../IFailureMechanismPropertyChangeHandler.cs)	(revision d819ea1eaeed69d333b425c911c370397a24dc0f)
+++ Ringtoets/Common/src/Ringtoets.Common.Forms/PropertyClasses/IFailureMechanismPropertyChangeHandler.cs	(.../IFailureMechanismPropertyChangeHandler.cs)	(revision a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501)
@@ -6,10 +6,20 @@
 namespace Ringtoets.Common.Forms.PropertyClasses
 {
     /// <summary>
+    /// Action in which a property of the <paramref name="failureMechanism"/> is set to the given <paramref name="value"/>.
+    /// </summary>
+    /// <typeparam name="TFailureMechanism">The type of the failure mechanism that is passed as argument.</typeparam>
+    /// <typeparam name="TValue">The type of the value that is set on a property of the failure mechanism.</typeparam>
+    /// <param name="failureMechanism">The failure mechanism for which the property will be set.</param>
+    /// <param name="value">The new value of the failure mechanism property.</param>
+    public delegate void SetFailureMechanismPropertyValueDelegate<in TFailureMechanism, in TValue>(TFailureMechanism failureMechanism, TValue value)
+        where TFailureMechanism : IFailureMechanism;
+
+    /// <summary>
     /// Interface for an object that can properly handle data model changes due to a change of a
     /// failure mechanism property.
     /// </summary>
-    public interface IFailureMechanismPropertyChangeHandler<in T> where T : IFailureMechanism
+    public interface IFailureMechanismPropertyChangeHandler<T> where T : IFailureMechanism
     {
         /// <summary>
         /// Checks whether a call to <see cref="PropertyChanged"/> would have any effect in the given
@@ -37,5 +47,23 @@
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="failureMechanism"/>
         /// is <c>null</c>.</exception>
         IEnumerable<IObservable> PropertyChanged(T failureMechanism);
+
+        /// <summary>
+        /// Find out whether the property can be updated with or without confirmation. If confirmation is required, 
+        /// the confirmation is obtained, after which the property is set if confirmation is given. If no confirmation
+        /// was required, then the value will be set for the property.
+        /// </summary>
+        /// <typeparam name="TValue">The type of the value that is set on a property of the failure mechanism.</typeparam>
+        /// <param name="failureMechanism">The failure mechanism for which the property is supposed to be set.</param>
+        /// <param name="value">The new value of the failure mechanism property.</param>
+        /// <param name="setValue">The operation which is performed to set the new property <paramref name="value"/>
+        /// on the <paramref name="failureMechanism"/>.</param>
+        /// <exception cref="ArgumentNullException">Thrown when any input parameter is <c>null</c>.</exception>
+        /// <remarks>Let <paramref name="setValue"/> throw an <see cref="Exception"/> when the 
+        /// <see cref="FailureMechanismPropertyChangeHandler{T}"/> should not process the results of that operation.</remarks>
+        IEnumerable<IObservable> SetPropertyValueAfterConfirmation<TValue>(
+            T failureMechanism,
+            TValue value,
+            SetFailureMechanismPropertyValueDelegate<T, TValue> setValue);
     }
 }
\ No newline at end of file
Index: Ringtoets/Common/src/Ringtoets.Common.Forms/Ringtoets.Common.Forms.csproj
===================================================================
diff -u -rdf1f3c0c408e42ef49e30ee9477f6bece0442b0b -ra1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501
--- Ringtoets/Common/src/Ringtoets.Common.Forms/Ringtoets.Common.Forms.csproj	(.../Ringtoets.Common.Forms.csproj)	(revision df1f3c0c408e42ef49e30ee9477f6bece0442b0b)
+++ Ringtoets/Common/src/Ringtoets.Common.Forms/Ringtoets.Common.Forms.csproj	(.../Ringtoets.Common.Forms.csproj)	(revision a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501)
@@ -48,7 +48,6 @@
     <Compile Include="FailureMechanismPropertyChangeHandler.cs" />
     <Compile Include="GuiServices\HydraulicBoundaryLocationCalculationGuiService.cs" />
     <Compile Include="GuiServices\IHydraulicBoundaryLocationCalculationGuiService.cs" />
-    <Compile Include="Helpers\IFailureMechanismPropertyChangeHandlerExtensions.cs" />
     <Compile Include="Helpers\SelectableHydraulicBoundaryLocationHelper.cs" />
     <Compile Include="Helpers\SuspendDataGridViewColumnResizes.cs" />
     <Compile Include="Helpers\NamingHelper.cs" />
Index: Ringtoets/Common/test/Ringtoets.Common.Forms.Test/FailureMechanismPropertyChangeHandlerTest.cs
===================================================================
diff -u -rc016f7af2a4afdc96fc19b8db86dc8d3559de023 -ra1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501
--- Ringtoets/Common/test/Ringtoets.Common.Forms.Test/FailureMechanismPropertyChangeHandlerTest.cs	(.../FailureMechanismPropertyChangeHandlerTest.cs)	(revision c016f7af2a4afdc96fc19b8db86dc8d3559de023)
+++ Ringtoets/Common/test/Ringtoets.Common.Forms.Test/FailureMechanismPropertyChangeHandlerTest.cs	(.../FailureMechanismPropertyChangeHandlerTest.cs)	(revision a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501)
@@ -107,6 +107,194 @@
             CollectionAssert.AreEquivalent(testCase.ExpectedAffectedCalculations, result);
         }
 
+        [Test]
+        public void SetPropertyValueAfterConfirmation_WithoutFailureMechanism_ThrowsArgumentNullException()
+        {
+            // Setup
+            var changeHandler = new FailureMechanismPropertyChangeHandler<IFailureMechanism>();
+
+            // Call
+            TestDelegate test = () => changeHandler.SetPropertyValueAfterConfirmation<int>(
+                null,
+                3,
+                (f, v) => { });
+
+            // Assert
+            var paramName = Assert.Throws<ArgumentNullException>(test).ParamName;
+            Assert.AreEqual("failureMechanism", paramName);
+        }
+
+        [Test]
+        public void SetPropertyValueAfterConfirmation_WithoutValue_ThrowsArgumentNullException()
+        {
+            // Setup
+            var changeHandler = new FailureMechanismPropertyChangeHandler<IFailureMechanism>();
+
+            // Call
+            TestDelegate test = () => changeHandler.SetPropertyValueAfterConfirmation<int?>(
+                new TestFailureMechanism(),
+                null,
+                (f, v) => { });
+
+            // Assert
+            var paramName = Assert.Throws<ArgumentNullException>(test).ParamName;
+            Assert.AreEqual("value", paramName);
+        }
+
+        [Test]
+        public void SetPropertyValueAfterConfirmation_WithoutSetProperty_ThrowsArgumentNullException()
+        {
+            // Setup
+            var changeHandler = new FailureMechanismPropertyChangeHandler<IFailureMechanism>();
+
+            // Call
+            TestDelegate test = () => changeHandler.SetPropertyValueAfterConfirmation(
+                new TestFailureMechanism(),
+                3,
+                null);
+
+            // Assert
+            var paramName = Assert.Throws<ArgumentNullException>(test).ParamName;
+            Assert.AreEqual("setValue", paramName);
+        }
+
+        [Test]
+        public void SetPropertyValueAfterConfirmation_ConfirmationRequiredAndGiven_SetValueCalledAffectedObjectsReturned()
+        {
+            // Setup
+            DialogBoxHandler = (name, wnd) =>
+            {
+                var tester = new MessageBoxTester(wnd);
+                tester.ClickOk();
+            };
+
+            var calculationWithOutput = CreateCalculationWithOutput();
+            var calculationWithoutOutput = CreateCalculationWithoutOutput();
+
+            var testFailureMechanism = new TestFailureMechanism(
+                new []
+                {
+                    calculationWithOutput,
+                    calculationWithoutOutput
+                });
+            var propertySet = 0;
+
+            var changeHandler = new FailureMechanismPropertyChangeHandler<IFailureMechanism>();
+            
+            // Call
+            var affectedObjects = changeHandler.SetPropertyValueAfterConfirmation(
+                testFailureMechanism,
+                3,
+                (f, v) => propertySet++);
+
+            // Assert
+            Assert.AreEqual(1, propertySet);
+            CollectionAssert.AreEqual(new IObservable[] { calculationWithOutput, testFailureMechanism }, affectedObjects);
+        }
+
+        [Test]
+        public void SetPropertyValueAfterConfirmation_ConfirmationNotRequired_SetValueCalledAffectedObjectsReturned()
+        {
+            // Setup
+            var testFailureMechanism = new TestFailureMechanism();
+            var propertySet = 0;
+
+            var changeHandler = new FailureMechanismPropertyChangeHandler<IFailureMechanism>();
+
+            // Call
+            var affectedObjects = changeHandler.SetPropertyValueAfterConfirmation(
+                testFailureMechanism,
+                3,
+                (f, v) => propertySet++);
+
+            // Assert
+            Assert.AreEqual(1, propertySet);
+            CollectionAssert.AreEqual(new IObservable[] { testFailureMechanism }, affectedObjects);
+        }
+
+        [Test]
+        public void SetPropertyValueAfterConfirmation_ConfirmationRequiredButNotGiven_SetValueNotCalledNoAffectedObjectsReturned()
+        {
+            // Setup
+            DialogBoxHandler = (name, wnd) =>
+            {
+                var tester = new MessageBoxTester(wnd);
+                tester.ClickCancel();
+            };
+
+            var calculationWithOutput = CreateCalculationWithOutput();
+            var calculationWithoutOutput = CreateCalculationWithoutOutput();
+
+            var testFailureMechanism = new TestFailureMechanism(
+                new[]
+                {
+                    calculationWithOutput,
+                    calculationWithoutOutput
+                });
+            var propertySet = 0;
+
+            var changeHandler = new FailureMechanismPropertyChangeHandler<IFailureMechanism>();
+            
+            // Call
+            var affectedObjects = changeHandler.SetPropertyValueAfterConfirmation(
+                testFailureMechanism,
+                3,
+                (f, v) => propertySet++);
+
+            // Assert
+            Assert.AreEqual(0, propertySet);
+            CollectionAssert.IsEmpty(affectedObjects);
+        }
+
+        [Test]
+        public void SetPropertyValueAfterConfirmation_ExceptionInSetValueAfterConfirmation_ExceptionBubbled()
+        {
+            // Setup
+            DialogBoxHandler = (name, wnd) =>
+            {
+                var tester = new MessageBoxTester(wnd);
+                tester.ClickOk();
+            };
+
+            var testFailureMechanism = new TestFailureMechanism(
+                new[]
+                {
+                    CreateCalculationWithOutput(),
+                });
+
+            var changeHandler = new FailureMechanismPropertyChangeHandler<IFailureMechanism>();
+            var expectedException = new Exception();
+
+            // Call
+            TestDelegate test = () => changeHandler.SetPropertyValueAfterConfirmation(
+                testFailureMechanism,
+                3,
+                (f, v) => { throw expectedException; });
+
+            // Assert
+            var exception = Assert.Throws<Exception>(test);
+            Assert.AreSame(expectedException, exception);
+        }
+
+        [Test]
+        public void SetPropertyValueAfterConfirmation_ConfirmationNotRequiredExceptionInSetValue_ExceptionBubbled()
+        {
+            // Setup
+            var testFailureMechanism = new TestFailureMechanism();
+            var changeHandler = new FailureMechanismPropertyChangeHandler<IFailureMechanism>();
+            var expectedException = new Exception();
+
+            // Call
+            TestDelegate test = () => changeHandler.SetPropertyValueAfterConfirmation(
+                testFailureMechanism,
+                3,
+                (f, v) => { throw expectedException; });
+
+            // Assert
+            var exception = Assert.Throws<Exception>(test);
+            Assert.AreSame(expectedException, exception);
+        }
+
         public class ChangePropertyTestCase
         {
             public ChangePropertyTestCase(ICollection<TestCalculation> calculations)
Fisheye: Tag a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501 refers to a dead (removed) revision in file `Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Helpers/IFailureMechanismPropertyChangeHandlerExtensionsTest.cs'.
Fisheye: No comparison available.  Pass `N' to diff?
Index: Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Ringtoets.Common.Forms.Test.csproj
===================================================================
diff -u -rdf1f3c0c408e42ef49e30ee9477f6bece0442b0b -ra1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501
--- Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Ringtoets.Common.Forms.Test.csproj	(.../Ringtoets.Common.Forms.Test.csproj)	(revision df1f3c0c408e42ef49e30ee9477f6bece0442b0b)
+++ Ringtoets/Common/test/Ringtoets.Common.Forms.Test/Ringtoets.Common.Forms.Test.csproj	(.../Ringtoets.Common.Forms.Test.csproj)	(revision a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501)
@@ -65,7 +65,6 @@
     </Compile>
     <Compile Include="FailureMechanismPropertyChangeHandlerTest.cs" />
     <Compile Include="GuiServices\HydraulicBoundaryLocationCalculationGuiServiceTest.cs" />
-    <Compile Include="Helpers\IFailureMechanismPropertyChangeHandlerExtensionsTest.cs" />
     <Compile Include="Helpers\NamingHelperTest.cs" />
     <Compile Include="Helpers\ProbabilityFormattingHelperTest.cs" />
     <Compile Include="Helpers\SelectableHydraulicBoundaryLocationHelperTest.cs" />
Index: Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/PipingFailureMechanismContextProperties.cs
===================================================================
diff -u -rdf1f3c0c408e42ef49e30ee9477f6bece0442b0b -ra1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501
--- Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/PipingFailureMechanismContextProperties.cs	(.../PipingFailureMechanismContextProperties.cs)	(revision df1f3c0c408e42ef49e30ee9477f6bece0442b0b)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/PipingFailureMechanismContextProperties.cs	(.../PipingFailureMechanismContextProperties.cs)	(revision a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501)
@@ -20,13 +20,12 @@
 // All rights reserved.
 
 using System;
+using System.Collections.Generic;
 using Core.Common.Base;
 using Core.Common.Base.Data;
 using Core.Common.Gui.Attributes;
 using Core.Common.Gui.PropertyBag;
 using Core.Common.Utils.Attributes;
-using Ringtoets.Common.Data.FailureMechanism;
-using Ringtoets.Common.Forms.Helpers;
 using Ringtoets.Common.Forms.PropertyClasses;
 using Ringtoets.Piping.Data;
 using Ringtoets.Piping.Forms.PresentationObjects;
@@ -40,7 +39,7 @@
     /// </summary>
     public class PipingFailureMechanismContextProperties : ObjectProperties<PipingFailureMechanismContext>
     {
-        private readonly IFailureMechanismPropertyChangeHandler<IFailureMechanism> propertyChangeHandler;
+        private readonly IFailureMechanismPropertyChangeHandler<PipingFailureMechanism> propertyChangeHandler;
 
         /// <summary>
         /// Creates a new instance of <see cref="PipingFailureMechanismContextProperties"/>.
@@ -50,7 +49,7 @@
         /// <exception cref="ArgumentNullException">Thrown when any input parameter is <c>null</c>.</exception>
         public PipingFailureMechanismContextProperties(
             PipingFailureMechanismContext data,
-            IFailureMechanismPropertyChangeHandler<IFailureMechanism> handler)
+            IFailureMechanismPropertyChangeHandler<PipingFailureMechanism> handler)
         {
             if (data == null)
             {
@@ -118,10 +117,12 @@
             }
             set
             {
-                propertyChangeHandler.SetPropertyValueAfterConfirmation(
+                IEnumerable<IObservable> affectedObjects = propertyChangeHandler.SetPropertyValueAfterConfirmation(
                     data.WrappedData,
                     value, 
                     (f,v) => f.GeneralInput.WaterVolumetricWeight = v);
+
+                NotifyAffectedObjects(affectedObjects);
             }
         }
 
@@ -169,10 +170,12 @@
             }
             set
             {
-                propertyChangeHandler.SetPropertyValueAfterConfirmation(
+                IEnumerable<IObservable> affectedObjects = propertyChangeHandler.SetPropertyValueAfterConfirmation(
                     data.WrappedData, 
                     value, 
                     (f, v) => f.PipingProbabilityAssessmentInput.A = v);
+
+                NotifyAffectedObjects(affectedObjects);
             }
         }
 
@@ -278,5 +281,12 @@
 
         #endregion
 
+        private static void NotifyAffectedObjects(IEnumerable<IObservable> affectedObjects)
+        {
+            foreach (var affectedObject in affectedObjects)
+            {
+                affectedObject.NotifyObservers();
+            }
+        }
     }
 }
\ No newline at end of file
Index: Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs
===================================================================
diff -u -rc016f7af2a4afdc96fc19b8db86dc8d3559de023 -ra1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501
--- Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs	(.../PipingPlugin.cs)	(revision c016f7af2a4afdc96fc19b8db86dc8d3559de023)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Plugin/PipingPlugin.cs	(.../PipingPlugin.cs)	(revision a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501)
@@ -69,7 +69,7 @@
         {
             yield return new PropertyInfo<PipingFailureMechanismContext, PipingFailureMechanismContextProperties>
             {
-                CreateInstance = context => new PipingFailureMechanismContextProperties(context, new FailureMechanismPropertyChangeHandler<IFailureMechanism>())
+                CreateInstance = context => new PipingFailureMechanismContextProperties(context, new FailureMechanismPropertyChangeHandler<PipingFailureMechanism>())
             };
             yield return new PropertyInfo<PipingInputContext, PipingInputContextProperties>();
             yield return new PropertyInfo<PipingOutputContext, PipingOutputContextProperties>();
Index: Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/PipingFailureMechanismContextPropertiesTest.cs
===================================================================
diff -u -rd819ea1eaeed69d333b425c911c370397a24dc0f -ra1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501
--- Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/PipingFailureMechanismContextPropertiesTest.cs	(.../PipingFailureMechanismContextPropertiesTest.cs)	(revision d819ea1eaeed69d333b425c911c370397a24dc0f)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/PipingFailureMechanismContextPropertiesTest.cs	(.../PipingFailureMechanismContextPropertiesTest.cs)	(revision a1f3f9aad8b2f6e3663a7ebd8915d0c4ed664501)
@@ -20,6 +20,7 @@
 // All rights reserved.
 
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
 using Core.Common.Base;
@@ -29,7 +30,6 @@
 using NUnit.Framework;
 using Rhino.Mocks;
 using Ringtoets.Common.Data.AssessmentSection;
-using Ringtoets.Common.Data.FailureMechanism;
 using Ringtoets.Common.Data.TestUtil;
 using Ringtoets.Common.Forms.PropertyClasses;
 using Ringtoets.Piping.Data;
@@ -46,7 +46,7 @@
         {
             // Setup
             var mocks = new MockRepository();
-            var handler = mocks.Stub<IFailureMechanismPropertyChangeHandler<IFailureMechanism>>();
+            var handler = mocks.Stub<IFailureMechanismPropertyChangeHandler<PipingFailureMechanism>>();
             mocks.ReplayAll();
 
             // Call
@@ -85,7 +85,7 @@
 
             var mockRepository = new MockRepository();
             var assessmentSectionStub = mockRepository.Stub<IAssessmentSection>();
-            var handler = mockRepository.Stub<IFailureMechanismPropertyChangeHandler<IFailureMechanism>>();
+            var handler = mockRepository.Stub<IFailureMechanismPropertyChangeHandler<PipingFailureMechanism>>();
             mockRepository.ReplayAll();
 
             // Call
@@ -128,7 +128,7 @@
 
             var mockRepository = new MockRepository();
             var assessmentSectionStub = mockRepository.Stub<IAssessmentSection>();
-            var handler = mockRepository.Stub<IFailureMechanismPropertyChangeHandler<IFailureMechanism>>();
+            var handler = mockRepository.Stub<IFailureMechanismPropertyChangeHandler<PipingFailureMechanism>>();
 
             mockRepository.ReplayAll();
 
@@ -259,27 +259,31 @@
         [TestCase(-0.1)]
         [TestCase(1.1)]
         [TestCase(8)]
-        public void A_SetInvalidValueWithConfirmation_ThrowsArgumentException(double value)
+        public void A_SetInvalidValue_ThrowsArgumentException(double value)
         {
             // Setup
             var failureMechanism = new PipingFailureMechanism();
 
             var mocks = new MockRepository();
-            var assessmentSection = mocks.Stub<IAssessmentSection>();
-            var observerMock = mocks.StrictMock<IObserver>();
+            var observableMock = mocks.StrictMock<IObservable>();
 
-            var changeHandler = mocks.Stub<IFailureMechanismPropertyChangeHandler<IFailureMechanism>>();
-            changeHandler.Expect(h => h.RequiresConfirmation(failureMechanism)).Return(true);
-            changeHandler.Expect(h => h.ConfirmPropertyChange()).Return(true);
+            var changeHandler = CreateStubChangeHandler(
+                mocks,
+                failureMechanism,
+                value,
+                new[]
+                {
+                    observableMock
+                });
 
+            var assessmentSection = mocks.Stub<IAssessmentSection>();
+
             mocks.ReplayAll();
 
             var properties = new PipingFailureMechanismContextProperties(
                 new PipingFailureMechanismContext(failureMechanism, assessmentSection),
                 changeHandler);
 
-            failureMechanism.Attach(observerMock);
-
             // Call
             TestDelegate call = () => properties.A = value;
 
@@ -296,29 +300,28 @@
         [TestCase(1)]
         [TestCase(0.0000001)]
         [TestCase(0.9999999)]
-        public void A_SetValidValueWithConfirmation_SetsValueAndUpdatesObservers(double value)
+        public void A_SetValidValue_SetsValueAndUpdatesObservers(double value)
         {
             // Setup
             var failureMechanism = new PipingFailureMechanism();
 
             var mocks = new MockRepository();
-            var observerMock = mocks.StrictMock<IObserver>();
-            observerMock.Expect(o => o.UpdateObserver());
-
             var observableMock = mocks.StrictMock<IObservable>();
             observableMock.Expect(o => o.NotifyObservers());
 
-            var changeHandler = mocks.Stub<IFailureMechanismPropertyChangeHandler<IFailureMechanism>>();
-            changeHandler.Expect(h => h.RequiresConfirmation(failureMechanism)).Return(true);
-            changeHandler.Expect(h => h.ConfirmPropertyChange()).Return(true);
-            changeHandler.Expect(h => h.PropertyChanged(failureMechanism)).Return(new [] { observableMock });
+            var changeHandler = CreateStubChangeHandler(
+                mocks,
+                failureMechanism,
+                value,
+                new[]
+                {
+                    observableMock
+                });
 
             var assessmentSection = mocks.Stub<IAssessmentSection>();
 
             mocks.ReplayAll();
 
-            failureMechanism.Attach(observerMock);
-
             var properties = new PipingFailureMechanismContextProperties(
                 new PipingFailureMechanismContext(failureMechanism, assessmentSection),
                 changeHandler);
@@ -332,73 +335,38 @@
         }
 
         [Test]
-        [TestCase(-1)]
-        [TestCase(-0.1)]
-        [TestCase(1.1)]
-        [TestCase(8)]
-        [TestCase(1)]
-        [TestCase(10)]
-        [TestCase(20)]
-        public void A_SetValidNoConfirmation_NoValueChangeNoUpdates(double value)
-        {
-            // Setup
-            var failureMechanism = new PipingFailureMechanism();
-
-            var mockRepository = new MockRepository();
-            var observerMock = mockRepository.StrictMock<IObserver>();
-
-            var changeHandler = mockRepository.StrictMock<IFailureMechanismPropertyChangeHandler<IFailureMechanism>>();
-            changeHandler.Expect(h => h.RequiresConfirmation(failureMechanism)).Return(true);
-            changeHandler.Expect(h => h.ConfirmPropertyChange()).Return(false);
-
-            var assessmentSection = mockRepository.Stub<IAssessmentSection>();
-
-            mockRepository.ReplayAll();
-
-            failureMechanism.Attach(observerMock);
-
-            var properties = new PipingFailureMechanismContextProperties(
-                new PipingFailureMechanismContext(failureMechanism, assessmentSection),
-                changeHandler);
-            double oldValue = properties.A;
-
-            // Call
-            properties.A = value;
-
-            // Assert
-            Assert.AreEqual(oldValue, failureMechanism.PipingProbabilityAssessmentInput.A);
-            mockRepository.VerifyAll();
-        }
-
-        [Test]
         [TestCase(double.NaN)]
         [TestCase(double.NegativeInfinity)]
         [TestCase(double.PositiveInfinity)]
         [TestCase(-0.005)]
         [TestCase(20.005)]
-        public void WaterVolumetricWeight_SetInvalidValueWithConfirmation_ThrowArgumentExceptionAndDoesNotUpdateObservers(double value)
+        public void WaterVolumetricWeight_SetInvalidValue_ThrowArgumentExceptionAndDoesNotUpdateObservers(double value)
         {
             // Setup
             var failureMechanism = new PipingFailureMechanism();
+            var roundedValue = (RoundedDouble) value;
 
             var mocks = new MockRepository();
-            var observerMock = mocks.StrictMock<IObserver>();
+            var observableMock = mocks.StrictMock<IObservable>();
             var assessmentSection = mocks.Stub<IAssessmentSection>();
 
-            var changeHandler = mocks.Stub<IFailureMechanismPropertyChangeHandler<IFailureMechanism>>();
-            changeHandler.Expect(h => h.RequiresConfirmation(failureMechanism)).Return(true);
-            changeHandler.Expect(h => h.ConfirmPropertyChange()).Return(true);
+            var changeHandler = CreateStubChangeHandler(
+                mocks,
+                failureMechanism,
+                roundedValue,
+                new[]
+                {
+                    observableMock
+                });
 
             mocks.ReplayAll();
-
-            failureMechanism.Attach(observerMock);
-
+            
             var properties = new PipingFailureMechanismContextProperties(
                 new PipingFailureMechanismContext(failureMechanism, assessmentSection),
                 changeHandler);
 
             // Call            
-            TestDelegate test = () => properties.WaterVolumetricWeight = (RoundedDouble) value;
+            TestDelegate test = () => properties.WaterVolumetricWeight = roundedValue;
 
             // Assert
             TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentOutOfRangeException>(test, "De waarde moet binnen het bereik [0, 20] liggen.");
@@ -409,78 +377,61 @@
         [TestCase(5)]
         [TestCase(-0.004)]
         [TestCase(20.004)]
-        public void WaterVolumetricWeight_SetValidValueWithConfirmation_SetsValueRoundedAndUpdatesObservers(double value)
+        public void WaterVolumetricWeight_SetValidValue_SetsValueRoundedAndUpdatesObservers(double value)
         {
             // Setup
             var failureMechanism = new PipingFailureMechanism();
+            var roundedValue = (RoundedDouble)value;
 
             var mocks = new MockRepository();
             var assessmentSection = mocks.Stub<IAssessmentSection>();
-            var observerMock = mocks.StrictMock<IObserver>();
-            observerMock.Expect(o => o.UpdateObserver());
 
             var observableMock = mocks.StrictMock<IObservable>();
             observableMock.Expect(o => o.NotifyObservers());
 
-            var handler = mocks.Stub<IFailureMechanismPropertyChangeHandler<IFailureMechanism>>();
-            handler.Expect(h => h.RequiresConfirmation(failureMechanism)).Return(true);
-            handler.Expect(h => h.ConfirmPropertyChange()).Return(true);
-            handler.Expect(h => h.PropertyChanged(failureMechanism)).Return(new[] { observableMock });
+            var changeHandler = CreateStubChangeHandler(
+                mocks,
+                failureMechanism,
+                roundedValue,
+                new[]
+                {
+                    observableMock
+                });
 
             mocks.ReplayAll();
 
-            failureMechanism.Attach(observerMock);
-
             var properties = new PipingFailureMechanismContextProperties(
                 new PipingFailureMechanismContext(failureMechanism, assessmentSection),
-                handler);
+                changeHandler);
 
             // Call            
-            properties.WaterVolumetricWeight = (RoundedDouble) value;
+            properties.WaterVolumetricWeight = roundedValue;
 
             // Assert
             Assert.AreEqual(value, failureMechanism.GeneralInput.WaterVolumetricWeight.Value, failureMechanism.GeneralInput.WaterVolumetricWeight.GetAccuracy());
             mocks.VerifyAll();
         }
-
-        [Test]
-        [TestCase(double.NaN)]
-        [TestCase(double.NegativeInfinity)]
-        [TestCase(double.PositiveInfinity)]
-        [TestCase(-0.005)]
-        [TestCase(20.005)]
-        [TestCase(5)]
-        [TestCase(-0.004)]
-        [TestCase(20.004)]
-        public void WaterVolumetricWeight_SetValueNoConfirmation_NoValueChangeNoUpdates(double value)
+        
+        private static IFailureMechanismPropertyChangeHandler<PipingFailureMechanism> CreateStubChangeHandler<T>(
+            MockRepository mocks,
+            PipingFailureMechanism failureMechanism,
+            T value,
+            IEnumerable<IObservable> affectedObjects)
         {
-            // Setup
-            var failureMechanism = new PipingFailureMechanism();
-
-            var mocks = new MockRepository();
-            var observerMock = mocks.StrictMock<IObserver>();
-            var assessmentSection = mocks.Stub<IAssessmentSection>();
-
-            var changeHandler = mocks.StrictMock<IFailureMechanismPropertyChangeHandler<IFailureMechanism>>();
-            changeHandler.Expect(h => h.RequiresConfirmation(failureMechanism)).Return(true);
-            changeHandler.Expect(h => h.ConfirmPropertyChange()).Return(false);
-
-            mocks.ReplayAll();
-
-            failureMechanism.Attach(observerMock);
-
-            var properties = new PipingFailureMechanismContextProperties(
-                new PipingFailureMechanismContext(failureMechanism, assessmentSection),
-                changeHandler);
-
-            RoundedDouble oldValue = properties.WaterVolumetricWeight;
-
-            // Call            
-            properties.WaterVolumetricWeight = (RoundedDouble) value;
-
-            // Assert
-            Assert.AreEqual(oldValue, failureMechanism.GeneralInput.WaterVolumetricWeight.Value, failureMechanism.GeneralInput.WaterVolumetricWeight.GetAccuracy());
-            mocks.VerifyAll();
+            var changeHandler = mocks.Stub<IFailureMechanismPropertyChangeHandler<PipingFailureMechanism>>();
+            changeHandler.Expect(h => h.SetPropertyValueAfterConfirmation(
+                                     Arg<PipingFailureMechanism>.Is.Same(failureMechanism),
+                                     Arg<T>.Is.Equal(value),
+                                     Arg<SetFailureMechanismPropertyValueDelegate<PipingFailureMechanism, T>>.Is.NotNull))
+                         .WhenCalled(m =>
+                                     {
+                                         var action = (SetFailureMechanismPropertyValueDelegate<PipingFailureMechanism, T>) m.Arguments[2];
+                                         var fm = (PipingFailureMechanism) m.Arguments[0];
+                                         var v = (T) m.Arguments[1];
+                                         action(fm, v);
+                                     })
+                         .Return(affectedObjects);
+            return changeHandler;
         }
     }
 }
\ No newline at end of file