Index: Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.KernelWrapper.TestUtil.Test/MacroStabilityInwardsCalculatorFactoryConfigTest.cs
===================================================================
diff -u -r966dc7335defa901104fd4168d57c08315db2de0 -r0c1eb485edd1764f19829f29bdad41e3343f35c1
--- Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.KernelWrapper.TestUtil.Test/MacroStabilityInwardsCalculatorFactoryConfigTest.cs	(.../MacroStabilityInwardsCalculatorFactoryConfigTest.cs)	(revision 966dc7335defa901104fd4168d57c08315db2de0)
+++ Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.KernelWrapper.TestUtil.Test/MacroStabilityInwardsCalculatorFactoryConfigTest.cs	(.../MacroStabilityInwardsCalculatorFactoryConfigTest.cs)	(revision 0c1eb485edd1764f19829f29bdad41e3343f35c1)
@@ -28,31 +28,38 @@
     public class MacroStabilityInwardsCalculatorFactoryConfigTest
     {
         [Test]
-        public void Constructor_FactoryNull_ThrowsArgumentNullException()
+        public void Constructor_NewInstanceCanBeDisposed()
         {
             // Call
-            TestDelegate call = () => new MacroStabilityInwardsCalculatorFactoryConfig(null);
+            var factory = new MacroStabilityInwardsCalculatorFactoryConfig();
 
             // Assert
-            var exception = Assert.Throws<ArgumentNullException>(call);
-            Assert.AreEqual("newFactory", exception.ParamName);
+            Assert.IsInstanceOf<IDisposable>(factory);
+            Assert.DoesNotThrow(() => factory.Dispose());
         }
 
         [Test]
-        public void Constructor_WithFactory_InstanceTemporarilyChanged()
+        public void Constructor_SetsTestFactoryForMacroStabilityInwardsCalculatorFactory()
         {
-            // Setup
-            IMacroStabilityInwardsCalculatorFactory originalInstance = MacroStabilityInwardsCalculatorFactory.Instance;
-            var factory = new TestMacroStabilityInwardsCalculatorFactory();
-
             // Call
-            using (var config = new MacroStabilityInwardsCalculatorFactoryConfig(factory))
+            using (new MacroStabilityInwardsCalculatorFactoryConfig())
             {
                 // Assert
-                Assert.IsInstanceOf<IDisposable>(config);
-                Assert.AreSame(factory, MacroStabilityInwardsCalculatorFactory.Instance);
+                Assert.IsInstanceOf<TestMacroStabilityInwardsCalculatorFactory>(MacroStabilityInwardsCalculatorFactory.Instance);
             }
-            Assert.AreSame(originalInstance, MacroStabilityInwardsCalculatorFactory.Instance);
         }
+
+        [Test]
+        public void Dispose_Always_ResetsFactoryToPreviousValue()
+        {
+            // Setup
+            IMacroStabilityInwardsCalculatorFactory expectedFactory = MacroStabilityInwardsCalculatorFactory.Instance;
+
+            // Call
+            using (new MacroStabilityInwardsCalculatorFactoryConfig()) { }
+
+            // Assert
+            Assert.AreSame(expectedFactory, MacroStabilityInwardsCalculatorFactory.Instance);
+        }
     }
 }
\ No newline at end of file
Index: Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.KernelWrapper.TestUtil/MacroStabilityInwardsCalculatorFactoryConfig.cs
===================================================================
diff -u -r966dc7335defa901104fd4168d57c08315db2de0 -r0c1eb485edd1764f19829f29bdad41e3343f35c1
--- Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.KernelWrapper.TestUtil/MacroStabilityInwardsCalculatorFactoryConfig.cs	(.../MacroStabilityInwardsCalculatorFactoryConfig.cs)	(revision 966dc7335defa901104fd4168d57c08315db2de0)
+++ Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.KernelWrapper.TestUtil/MacroStabilityInwardsCalculatorFactoryConfig.cs	(.../MacroStabilityInwardsCalculatorFactoryConfig.cs)	(revision 0c1eb485edd1764f19829f29bdad41e3343f35c1)
@@ -24,47 +24,41 @@
 namespace Ringtoets.MacroStabilityInwards.KernelWrapper.TestUtil
 {
     /// <summary>
-    /// This class can be used to set a temporary <see cref="IMacroStabilityInwardsCalculatorFactory"/>
-    /// for <see cref="MacroStabilityInwardsCalculatorFactory.Instance"/> while testing.
-    /// Disposing an instance of this class will revert the
+    /// This class can be used to set a temporary <see cref="TestMacroStabilityInwardsCalculatorFactory"/> 
+    /// for <see cref="MacroStabilityInwardsCalculatorFactory.Instance"/> while testing. 
+    /// Disposing an instance of this class will revert the 
     /// <see cref="MacroStabilityInwardsCalculatorFactory.Instance"/>.
     /// </summary>
     /// <example>
     /// The following is an example for how to use this class:
     /// <code>
-    /// var mockRepository = new MockRepository();
-    /// var calculatorFactory = mockRepository.Stub&lt;IMacroStabilityInwardsCalculatorFactory&gt;();
-    /// mockRepository.ReplayAll();
-    /// 
-    /// using(new MacroStabilityInwardsCalculatorFactoryConfig(calculatorFactory))
+    /// using(new MacroStabilityInwardsCalculatorFactoryConfig())
     /// {
-    ///     // Perform test with mocked factory
+    ///     var testFactory = (TestMacroStabilityInwardsCalculatorFactory) MacroStabilityInwardsCalculatorFactory.Instance;
+    /// 
+    ///     // Perform tests with testFactory
     /// }
     /// </code>
-    /// 
-    /// mockRepository.VerifyAll();
     /// </example>
     public class MacroStabilityInwardsCalculatorFactoryConfig : IDisposable
     {
         private readonly IMacroStabilityInwardsCalculatorFactory previousFactory;
 
         /// <summary>
         /// Creates a new instance of <see cref="MacroStabilityInwardsCalculatorFactoryConfig"/>.
-        /// Sets the <paramref name="newFactory"/> to <see cref="MacroStabilityInwardsCalculatorFactory.Instance"/>.
+        /// Sets a <see cref="TestMacroStabilityInwardsCalculatorFactory"/> to 
+        /// <see cref="MacroStabilityInwardsCalculatorFactory.Instance"/>
         /// </summary>
-        /// <param name="newFactory">The factory that will be used while testing.</param>
-        /// <exception cref="ArgumentNullException">Thrown when <paramref name="newFactory"/> 
-        /// is <c>null</c>.</exception>
-        public MacroStabilityInwardsCalculatorFactoryConfig(IMacroStabilityInwardsCalculatorFactory newFactory)
+        public MacroStabilityInwardsCalculatorFactoryConfig()
         {
-            if (newFactory == null)
-            {
-                throw new ArgumentNullException(nameof(newFactory));
-            }
             previousFactory = MacroStabilityInwardsCalculatorFactory.Instance;
-            MacroStabilityInwardsCalculatorFactory.Instance = newFactory;
+            MacroStabilityInwardsCalculatorFactory.Instance = new TestMacroStabilityInwardsCalculatorFactory();
         }
 
+        /// <summary>
+        /// Reverts the <see cref="MacroStabilityInwardsCalculatorFactory.Instance"/> to the value
+        /// it had at time of construction of the <see cref="MacroStabilityInwardsCalculatorFactoryConfig"/>.
+        /// </summary>
         public void Dispose()
         {
             MacroStabilityInwardsCalculatorFactory.Instance = previousFactory;
Index: Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Plugin.Test/TreeNodeInfos/MacroStabilityInwardsCalculationScenarioContextTreeNodeInfoTest.cs
===================================================================
diff -u -r966dc7335defa901104fd4168d57c08315db2de0 -r0c1eb485edd1764f19829f29bdad41e3343f35c1
--- Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Plugin.Test/TreeNodeInfos/MacroStabilityInwardsCalculationScenarioContextTreeNodeInfoTest.cs	(.../MacroStabilityInwardsCalculationScenarioContextTreeNodeInfoTest.cs)	(revision 966dc7335defa901104fd4168d57c08315db2de0)
+++ Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Plugin.Test/TreeNodeInfos/MacroStabilityInwardsCalculationScenarioContextTreeNodeInfoTest.cs	(.../MacroStabilityInwardsCalculationScenarioContextTreeNodeInfoTest.cs)	(revision 0c1eb485edd1764f19829f29bdad41e3343f35c1)
@@ -45,7 +45,6 @@
 using Ringtoets.MacroStabilityInwards.Data.SoilProfile;
 using Ringtoets.MacroStabilityInwards.Data.TestUtil;
 using Ringtoets.MacroStabilityInwards.Forms.PresentationObjects;
-using Ringtoets.MacroStabilityInwards.KernelWrapper;
 using Ringtoets.MacroStabilityInwards.KernelWrapper.TestUtil;
 using Ringtoets.MacroStabilityInwards.Primitives;
 using RingtoetsCommonFormsResources = Ringtoets.Common.Forms.Properties.Resources;
@@ -645,7 +644,7 @@
                     // Expect an activity dialog which is automatically closed
                 };
 
-                using(new MacroStabilityInwardsCalculatorFactoryConfig(new TestMacroStabilityInwardsCalculatorFactory()))
+                using (new MacroStabilityInwardsCalculatorFactoryConfig())
                 using (ContextMenuStrip contextMenuAdapter = info.ContextMenuStrip(calculationContext, null, treeViewControl))
                 {
                     // When
Index: Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Service.Test/MacroStabilityInwardsCalculationActivityTest.cs
===================================================================
diff -u -r966dc7335defa901104fd4168d57c08315db2de0 -r0c1eb485edd1764f19829f29bdad41e3343f35c1
--- Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Service.Test/MacroStabilityInwardsCalculationActivityTest.cs	(.../MacroStabilityInwardsCalculationActivityTest.cs)	(revision 966dc7335defa901104fd4168d57c08315db2de0)
+++ Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Service.Test/MacroStabilityInwardsCalculationActivityTest.cs	(.../MacroStabilityInwardsCalculationActivityTest.cs)	(revision 0c1eb485edd1764f19829f29bdad41e3343f35c1)
@@ -120,7 +120,7 @@
 
             double norm = new Random(21).NextDouble();
 
-            using (new MacroStabilityInwardsCalculatorFactoryConfig(new TestMacroStabilityInwardsCalculatorFactory()))
+            using (new MacroStabilityInwardsCalculatorFactoryConfig())
             {
                 var activity = new MacroStabilityInwardsCalculationActivity(validMacroStabilityInwardsCalculation, new MacroStabilityInwardsProbabilityAssessmentInput(), norm, double.NaN);
                 activity.Run();
Index: Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Service.Test/MacroStabilityInwardsCalculationServiceTest.cs
===================================================================
diff -u -r497172e737ffc201c0f905e85a246cdba3c0cb1c -r0c1eb485edd1764f19829f29bdad41e3343f35c1
--- Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Service.Test/MacroStabilityInwardsCalculationServiceTest.cs	(.../MacroStabilityInwardsCalculationServiceTest.cs)	(revision 497172e737ffc201c0f905e85a246cdba3c0cb1c)
+++ Ringtoets/MacroStabilityInwards/test/Ringtoets.MacroStabilityInwards.Service.Test/MacroStabilityInwardsCalculationServiceTest.cs	(.../MacroStabilityInwardsCalculationServiceTest.cs)	(revision 0c1eb485edd1764f19829f29bdad41e3343f35c1)
@@ -248,7 +248,7 @@
 
             testCalculation.Name = name;
 
-            using (new MacroStabilityInwardsCalculatorFactoryConfig(new TestMacroStabilityInwardsCalculatorFactory()))
+            using (new MacroStabilityInwardsCalculatorFactoryConfig())
             {
                 Action call = () =>
                 {
@@ -275,7 +275,7 @@
         public void Calculate_ValidCalculationNoOutput_ShouldSetOutput()
         {
             // Setup
-            using (new MacroStabilityInwardsCalculatorFactoryConfig(new TestMacroStabilityInwardsCalculatorFactory()))
+            using (new MacroStabilityInwardsCalculatorFactoryConfig())
             {
                 // Precondition
                 Assert.IsNull(testCalculation.Output);
@@ -297,7 +297,7 @@
 
             testCalculation.Output = output;
 
-            using (new MacroStabilityInwardsCalculatorFactoryConfig(new TestMacroStabilityInwardsCalculatorFactory()))
+            using (new MacroStabilityInwardsCalculatorFactoryConfig())
             {
                 // Precondition
                 Assert.IsTrue(MacroStabilityInwardsCalculationService.Validate(testCalculation));
@@ -314,7 +314,7 @@
         public void Calculate_CompleteInput_SetsInputOnCalculator()
         {
             // Setup
-            using (new MacroStabilityInwardsCalculatorFactoryConfig(new TestMacroStabilityInwardsCalculatorFactory()))
+            using (new MacroStabilityInwardsCalculatorFactoryConfig())
             {
                 // Call
                 MacroStabilityInwardsCalculationService.Calculate(testCalculation);
@@ -328,7 +328,7 @@
         public void Calculate_CalculationRan_SetOutput()
         {
             // Setup
-            using (new MacroStabilityInwardsCalculatorFactoryConfig(new TestMacroStabilityInwardsCalculatorFactory()))
+            using (new MacroStabilityInwardsCalculatorFactoryConfig())
             {
                 var calculatorFactory = (TestMacroStabilityInwardsCalculatorFactory) MacroStabilityInwardsCalculatorFactory.Instance;
 
Index: Ringtoets/Piping/test/Ringtoets.Piping.KernelWrapper.TestUtil.Test/SubCalculator/PipingSubCalculatorFactoryConfigTest.cs
===================================================================
diff -u -r81fa8a9bf3bd503cbd280e88b8f6037a840cff12 -r0c1eb485edd1764f19829f29bdad41e3343f35c1
--- Ringtoets/Piping/test/Ringtoets.Piping.KernelWrapper.TestUtil.Test/SubCalculator/PipingSubCalculatorFactoryConfigTest.cs	(.../PipingSubCalculatorFactoryConfigTest.cs)	(revision 81fa8a9bf3bd503cbd280e88b8f6037a840cff12)
+++ Ringtoets/Piping/test/Ringtoets.Piping.KernelWrapper.TestUtil.Test/SubCalculator/PipingSubCalculatorFactoryConfigTest.cs	(.../PipingSubCalculatorFactoryConfigTest.cs)	(revision 0c1eb485edd1764f19829f29bdad41e3343f35c1)
@@ -41,7 +41,7 @@
         }
 
         [Test]
-        public void Constructor_SetsTestFactoryForPipingCalculatorService()
+        public void Constructor_SetsTestFactoryForPipingSubCalculatorFactory()
         {
             // Call
             using (new PipingSubCalculatorFactoryConfig())
Index: Ringtoets/Piping/test/Ringtoets.Piping.KernelWrapper.TestUtil/SubCalculator/PipingSubCalculatorFactoryConfig.cs
===================================================================
diff -u -r81fa8a9bf3bd503cbd280e88b8f6037a840cff12 -r0c1eb485edd1764f19829f29bdad41e3343f35c1
--- Ringtoets/Piping/test/Ringtoets.Piping.KernelWrapper.TestUtil/SubCalculator/PipingSubCalculatorFactoryConfig.cs	(.../PipingSubCalculatorFactoryConfig.cs)	(revision 81fa8a9bf3bd503cbd280e88b8f6037a840cff12)
+++ Ringtoets/Piping/test/Ringtoets.Piping.KernelWrapper.TestUtil/SubCalculator/PipingSubCalculatorFactoryConfig.cs	(.../PipingSubCalculatorFactoryConfig.cs)	(revision 0c1eb485edd1764f19829f29bdad41e3343f35c1)
@@ -33,8 +33,9 @@
     /// <example>
     /// The following is an example for how to use this class:
     /// <code>
-    /// using(new PipingCalculationServiceConfig()) {
-    ///     var testFactory = (TestPipingSubCalculatorFactory) PipingCalculationService.SubCalculatorFactory;
+    /// using(new PipingSubCalculatorFactoryConfig())
+    /// {
+    ///     var testFactory = (TestPipingSubCalculatorFactory) PipingSubCalculatorFactory.Instance;
     /// 
     ///     // Perform tests with testFactory
     /// }