Index: Ringtoets/Piping/test/Ringtoets.Piping.Data.Test/PipingFailureMechanismSection2aAssessmentResultExtensionsTest.cs
===================================================================
diff -u -r77b27109212e94d58eb47248d4210f7eac243fb6 -r271e81c620b40ebce812a9595b22ed0e4e7ce94a
--- Ringtoets/Piping/test/Ringtoets.Piping.Data.Test/PipingFailureMechanismSection2aAssessmentResultExtensionsTest.cs	(.../PipingFailureMechanismSection2aAssessmentResultExtensionsTest.cs)	(revision 77b27109212e94d58eb47248d4210f7eac243fb6)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Data.Test/PipingFailureMechanismSection2aAssessmentResultExtensionsTest.cs	(.../PipingFailureMechanismSection2aAssessmentResultExtensionsTest.cs)	(revision 271e81c620b40ebce812a9595b22ed0e4e7ce94a)
@@ -19,6 +19,7 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using System;
 using System.Linq;
 using Core.Common.Base.Data;
 using NUnit.Framework;
@@ -35,6 +36,79 @@
     public class PipingFailureMechanismSection2aAssessmentResultExtensionsTest
     {
         [Test]
+        public void GetAssessmentLayerTwoA_SectionResultNull_ThrowsArgumentNullException()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var assessmentSection = mocks.Stub<IAssessmentSection>();
+            mocks.ReplayAll();
+
+            // Call
+            TestDelegate call = () => PipingFailureMechanismSection2aAssessmentResultExtensions.GetAssessmentLayerTwoA(null, Enumerable.Empty<PipingCalculationScenario>(),
+                                                                                                                       new PipingFailureMechanism(), assessmentSection);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(call);
+            Assert.AreEqual("sectionResult", exception.ParamName);
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        public void GetAssessmentLayerTwoA_CalculationsNull_ThrowsArgumentNullException()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var assessmentSection = mocks.Stub<IAssessmentSection>();
+            mocks.ReplayAll();
+
+            FailureMechanismSection section = FailureMechanismSectionTestFactory.CreateFailureMechanismSection();
+            var failureMechanismSectionResult = new PipingFailureMechanismSectionResult(section);
+
+            // Call
+            TestDelegate call = () => failureMechanismSectionResult.GetAssessmentLayerTwoA(null, new PipingFailureMechanism(), assessmentSection);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(call);
+            Assert.AreEqual("calculations", exception.ParamName);
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        public void GetAssessmentLayerTwoA_FailureMechanismNull_ThrowsArgumentNullException()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var assessmentSection = mocks.Stub<IAssessmentSection>();
+            mocks.ReplayAll();
+
+            FailureMechanismSection section = FailureMechanismSectionTestFactory.CreateFailureMechanismSection();
+            var failureMechanismSectionResult = new PipingFailureMechanismSectionResult(section);
+
+            // Call
+            TestDelegate call = () => failureMechanismSectionResult.GetAssessmentLayerTwoA(Enumerable.Empty<PipingCalculationScenario>(), null, assessmentSection);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(call);
+            Assert.AreEqual("failureMechanism", exception.ParamName);
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        public void GetAssessmentLayerTwoA_AssessmentSectionNull_ThrowsArgumentNullException()
+        {
+            // Setup
+            FailureMechanismSection section = FailureMechanismSectionTestFactory.CreateFailureMechanismSection();
+            var failureMechanismSectionResult = new PipingFailureMechanismSectionResult(section);
+
+            // Call
+            TestDelegate call = () => failureMechanismSectionResult.GetAssessmentLayerTwoA(Enumerable.Empty<PipingCalculationScenario>(), new PipingFailureMechanism(), null);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(call);
+            Assert.AreEqual("assessmentSection", exception.ParamName);
+        }
+
+        [Test]
         public void GetAssessmentLayerTwoA_MultipleScenarios_ReturnsValueBasedOnRelevantAndDoneScenarios()
         {
             // Setup