Index: Riskeer/GrassCoverErosionInwards/src/Riskeer.GrassCoverErosionInwards.Util/GrassCoverErosionInwardsIllustrationPointsHelper.cs
===================================================================
diff -u -rbb831b80442c0389546ce12572e24c795e0f6df6 -rb72098cbe278bd5b985a370cff6491c5c353fc7e
--- Riskeer/GrassCoverErosionInwards/src/Riskeer.GrassCoverErosionInwards.Util/GrassCoverErosionInwardsIllustrationPointsHelper.cs	(.../GrassCoverErosionInwardsIllustrationPointsHelper.cs)	(revision bb831b80442c0389546ce12572e24c795e0f6df6)
+++ Riskeer/GrassCoverErosionInwards/src/Riskeer.GrassCoverErosionInwards.Util/GrassCoverErosionInwardsIllustrationPointsHelper.cs	(.../GrassCoverErosionInwardsIllustrationPointsHelper.cs)	(revision b72098cbe278bd5b985a370cff6491c5c353fc7e)
@@ -65,21 +65,68 @@
             return calculations.Any(HasIllustrationPoints);
         }
 
-        private static bool HasIllustrationPoints(GrassCoverErosionInwardsOutput output)
+        /// <summary>
+        /// Determines whether a <see cref="GrassCoverErosionInwardsOutput"/>
+        /// has overtopping illustration point results.
+        /// </summary>
+        /// <param name="output">The output to check.</param>
+        /// <returns><c>true</c> when <paramref name="output"/> has overtopping illustration point results,
+        /// <c>false</c> otherwise.</returns>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="output"/>
+        /// is <c>null</c>.</exception>
+        public static bool HasOverToppingIllustrationPoints(GrassCoverErosionInwardsOutput output)
         {
-            return output.OvertoppingOutput.HasGeneralResult
-                   || HasDikeHeightOutputWithIllustrationPoints(output)
-                   || HasOverToppingRateOutputWithIllustrationPoints(output);
+            if (output == null)
+            {
+                throw new ArgumentNullException(nameof(output));
+            }
+
+            return output.OvertoppingOutput.HasGeneralResult;
         }
 
-        private static bool HasOverToppingRateOutputWithIllustrationPoints(GrassCoverErosionInwardsOutput output)
+        /// <summary>
+        /// Determines whether a <see cref="GrassCoverErosionInwardsOutput"/>
+        /// has overtopping dike height with illustration point results.
+        /// </summary>
+        /// <param name="output">The output to check.</param>
+        /// <returns><c>true</c> when <paramref name="output"/> has dike height output with illustration point results,
+        /// <c>false</c> otherwise.</returns>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="output"/>
+        /// is <c>null</c>.</exception>
+        public static bool HasDikeHeightOutputWithIllustrationPoints(GrassCoverErosionInwardsOutput output)
         {
+            if (output == null)
+            {
+                throw new ArgumentNullException(nameof(output));
+            }
+
+            return output.DikeHeightOutput != null && output.DikeHeightOutput.HasGeneralResult;
+        }
+
+        /// <summary>
+        /// Determines whether a <see cref="GrassCoverErosionInwardsOutput"/>
+        /// has overtopping rate output with illustration point results.
+        /// </summary>
+        /// <param name="output">The output to check.</param>
+        /// <returns><c>true</c> when <paramref name="output"/> has overtopping rate output with illustration point results,
+        /// <c>false</c> otherwise.</returns>
+        /// <exception cref="ArgumentNullException">Thrown when <paramref name="output"/>
+        /// is <c>null</c>.</exception>
+        public static bool HasOverToppingRateOutputWithIllustrationPoints(GrassCoverErosionInwardsOutput output)
+        {
+            if (output == null)
+            {
+                throw new ArgumentNullException(nameof(output));
+            }
+
             return output.OvertoppingRateOutput != null && output.OvertoppingRateOutput.HasGeneralResult;
         }
 
-        private static bool HasDikeHeightOutputWithIllustrationPoints(GrassCoverErosionInwardsOutput output)
+        private static bool HasIllustrationPoints(GrassCoverErosionInwardsOutput output)
         {
-            return output.DikeHeightOutput != null && output.DikeHeightOutput.HasGeneralResult;
+            return HasOverToppingIllustrationPoints(output)
+                   || HasDikeHeightOutputWithIllustrationPoints(output)
+                   || HasOverToppingRateOutputWithIllustrationPoints(output);
         }
     }
 }
\ No newline at end of file
Index: Riskeer/GrassCoverErosionInwards/test/Riskeer.GrassCoverErosionInwards.Util.Test/GrassCoverErosionInwardsIllustrationPointsHelperTest.cs
===================================================================
diff -u -r910cba21727c0cdc02a1310341784a227db32f53 -rb72098cbe278bd5b985a370cff6491c5c353fc7e
--- Riskeer/GrassCoverErosionInwards/test/Riskeer.GrassCoverErosionInwards.Util.Test/GrassCoverErosionInwardsIllustrationPointsHelperTest.cs	(.../GrassCoverErosionInwardsIllustrationPointsHelperTest.cs)	(revision 910cba21727c0cdc02a1310341784a227db32f53)
+++ Riskeer/GrassCoverErosionInwards/test/Riskeer.GrassCoverErosionInwards.Util.Test/GrassCoverErosionInwardsIllustrationPointsHelperTest.cs	(.../GrassCoverErosionInwardsIllustrationPointsHelperTest.cs)	(revision b72098cbe278bd5b985a370cff6491c5c353fc7e)
@@ -80,6 +80,120 @@
             Assert.AreEqual(expectedHasIllustrationPoints, hasIllustrationPoints);
         }
 
+        [Test]
+        public void HasOverToppingIllustrationPoints_OutputNull_ThrowsArgumentNullException()
+        {
+            // Call
+            void Call() => GrassCoverErosionInwardsIllustrationPointsHelper.HasOverToppingIllustrationPoints(null);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(Call);
+            Assert.AreEqual("output", exception.ParamName);
+        }
+
+        [Test]
+        [TestCase(true)]
+        [TestCase(false)]
+        public void HasOverToppingIllustrationPoints_WithOrWithoutIllustrationPoints_ReturnsExpectedResult(bool expectedHasIllustrationPoints)
+        {
+            // Setup
+            var output = new TestGrassCoverErosionInwardsOutput(
+                expectedHasIllustrationPoints
+                    ? new TestGeneralResultFaultTreeIllustrationPoint()
+                    : null);
+
+            // Call
+            bool hasIllustrationPoints = GrassCoverErosionInwardsIllustrationPointsHelper.HasOverToppingIllustrationPoints(output);
+
+            // Assert
+            Assert.AreEqual(expectedHasIllustrationPoints, hasIllustrationPoints);
+        }
+
+        [Test]
+        public void HasDikeHeightOutputWithIllustrationPoints_OutputNull_ThrowsArgumentNullException()
+        {
+            // Call
+            void Call() => GrassCoverErosionInwardsIllustrationPointsHelper.HasDikeHeightOutputWithIllustrationPoints(null);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(Call);
+            Assert.AreEqual("output", exception.ParamName);
+        }
+
+        [Test]
+        public void HasDikeHeightOutputWithIllustrationPoints_DikeHeightOutputNull_ReturnsFalse()
+        {
+            // Setup
+            var output = new GrassCoverErosionInwardsOutput(new TestOvertoppingOutput(0.1), null,
+                                                            new TestOvertoppingRateOutput(0.2));
+            // Call
+            bool hasIllustrationPoints = GrassCoverErosionInwardsIllustrationPointsHelper.HasDikeHeightOutputWithIllustrationPoints(output);
+
+            // Assert
+            Assert.IsFalse(hasIllustrationPoints);
+        }
+
+        [Test]
+        [TestCase(true)]
+        [TestCase(false)]
+        public void HasDikeHeightOutputWithIllustrationPoints_WithOrWithoutIllustrationPoints_ReturnsExpectedResult(bool expectedHasIllustrationPoints)
+        {
+            // Setup
+            var output = new TestGrassCoverErosionInwardsOutput(
+                expectedHasIllustrationPoints
+                    ? new TestGeneralResultFaultTreeIllustrationPoint()
+                    : null);
+
+            // Call
+            bool hasIllustrationPoints = GrassCoverErosionInwardsIllustrationPointsHelper.HasDikeHeightOutputWithIllustrationPoints(output);
+
+            // Assert
+            Assert.AreEqual(expectedHasIllustrationPoints, hasIllustrationPoints);
+        }
+
+        [Test]
+        public void HasOverToppingRateOutputWithIllustrationPoints_OutputNull_ThrowsArgumentNullException()
+        {
+            // Call
+            void Call() => GrassCoverErosionInwardsIllustrationPointsHelper.HasOverToppingRateOutputWithIllustrationPoints(null);
+
+            // Assert
+            var exception = Assert.Throws<ArgumentNullException>(Call);
+            Assert.AreEqual("output", exception.ParamName);
+        }
+
+        [Test]
+        public void HasOverToppingRateOutputWithIllustrationPoints_OvertoppingRateOutputNull_ReturnsFalse()
+        {
+            // Setup
+            var output = new GrassCoverErosionInwardsOutput(
+                new TestOvertoppingOutput(0.1), new TestDikeHeightOutput(0.2), null);
+
+            // Call
+            bool hasIllustrationPoints = GrassCoverErosionInwardsIllustrationPointsHelper.HasOverToppingRateOutputWithIllustrationPoints(output);
+
+            // Assert
+            Assert.IsFalse(hasIllustrationPoints);
+        }
+
+        [Test]
+        [TestCase(true)]
+        [TestCase(false)]
+        public void HasOverToppingRateOutputWithIllustrationPoints_WithOrWithoutIllustrationPoints_ReturnsExpectedResult(bool expectedHasIllustrationPoints)
+        {
+            // Setup
+            var output = new TestGrassCoverErosionInwardsOutput(
+                expectedHasIllustrationPoints
+                    ? new TestGeneralResultFaultTreeIllustrationPoint()
+                    : null);
+
+            // Call
+            bool hasIllustrationPoints = GrassCoverErosionInwardsIllustrationPointsHelper.HasOverToppingRateOutputWithIllustrationPoints(output);
+
+            // Assert
+            Assert.AreEqual(expectedHasIllustrationPoints, hasIllustrationPoints);
+        }
+
         private static IEnumerable<TestCaseData> GetCalculationCollectionConfigurations()
         {
             foreach (TestCaseData configuration in GetCalculationConfigurations())