Index: Application/Ringtoets/test/Application.Ringtoets.Storage.Test/Read/HeightStructures/HeightStructuresFailureMechanismMetaEntityReadExtensionsTest.cs
===================================================================
diff -u -rf7036a73fff399ef3c8524ffe9099e9b8fcbf3d8 -rfbe227cf3a6743302f63c1bd3281feda0273192c
--- Application/Ringtoets/test/Application.Ringtoets.Storage.Test/Read/HeightStructures/HeightStructuresFailureMechanismMetaEntityReadExtensionsTest.cs	(.../HeightStructuresFailureMechanismMetaEntityReadExtensionsTest.cs)	(revision f7036a73fff399ef3c8524ffe9099e9b8fcbf3d8)
+++ Application/Ringtoets/test/Application.Ringtoets.Storage.Test/Read/HeightStructures/HeightStructuresFailureMechanismMetaEntityReadExtensionsTest.cs	(.../HeightStructuresFailureMechanismMetaEntityReadExtensionsTest.cs)	(revision fbe227cf3a6743302f63c1bd3281feda0273192c)
@@ -19,8 +19,10 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using System;
 using Application.Ringtoets.Storage.DbContext;
 using Application.Ringtoets.Storage.Read.HeightStructures;
+using Core.Common.TestUtil;
 using NUnit.Framework;
 using Ringtoets.Common.Data.TestUtil;
 using Ringtoets.HeightStructures.Data;
@@ -31,12 +33,23 @@
     public class HeightStructuresFailureMechanismMetaEntityReadExtensionsTest
     {
         [Test]
+        public void ReadHeightStructuresFailureMechanism_EntityNull_ThrowsArgumentNullException()
+        {
+            // Call
+            TestDelegate test = () => ((HeightStructuresFailureMechanismMetaEntity) null).Read();
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(test);
+            Assert.AreEqual("entity", exception.ParamName);
+        }
+
+        [Test]
         public void Read_Always_ReturnGeneralHeightStructuresInput()
         {
             // Setup
             var entity = new HeightStructuresFailureMechanismMetaEntity
             {
-                N = 3
+                N = new Random(39).NextRoundedDouble(1.0, 20.0)
             };
 
             // Call