Index: Ringtoets/Common/test/Ringtoets.Common.Data.Test/AssessmentSection/BackgroundDataTest.cs
===================================================================
diff -u -r7a4f8ff71ae5f81177fe5ff9cd78fdc7f24c69f4 -r657e48b8886aa9641a3673f4fe9c4b81efc72260
--- Ringtoets/Common/test/Ringtoets.Common.Data.Test/AssessmentSection/BackgroundDataTest.cs	(.../BackgroundDataTest.cs)	(revision 7a4f8ff71ae5f81177fe5ff9cd78fdc7f24c69f4)
+++ Ringtoets/Common/test/Ringtoets.Common.Data.Test/AssessmentSection/BackgroundDataTest.cs	(.../BackgroundDataTest.cs)	(revision 657e48b8886aa9641a3673f4fe9c4b81efc72260)
@@ -19,6 +19,9 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
+using System;
+using Core.Common.Base.Data;
+using Core.Common.TestUtil;
 using NUnit.Framework;
 using Ringtoets.Common.Data.AssessmentSection;
 
@@ -31,15 +34,54 @@
         public void Constructor_ExpectedValues()
         {
             // Call 
-            var backgroundMapData = new BackgroundData();
+            var backgroundData = new BackgroundData();
 
             // Assert
-            Assert.IsTrue(backgroundMapData.IsVisible);
-            Assert.AreEqual(2, backgroundMapData.Transparency.NumberOfDecimalPlaces);
-            Assert.AreEqual(0, backgroundMapData.Transparency.Value);
-            Assert.AreEqual(BackgroundMapDataType.Wmts, backgroundMapData.BackgroundMapDataType);
-            Assert.IsFalse(backgroundMapData.IsConfigured);
-            CollectionAssert.IsEmpty(backgroundMapData.Parameters);
+            Assert.IsTrue(backgroundData.IsVisible);
+            Assert.AreEqual(2, backgroundData.Transparency.NumberOfDecimalPlaces);
+            Assert.AreEqual(0, backgroundData.Transparency.Value);
+            Assert.AreEqual(BackgroundMapDataType.Wmts, backgroundData.BackgroundMapDataType);
+            Assert.IsFalse(backgroundData.IsConfigured);
+            CollectionAssert.IsEmpty(backgroundData.Parameters);
         }
+        
+        [Test]
+        [TestCase(0)]
+        [TestCase(0.8)]
+        [TestCase(1)]
+        public void Transparency_ValidValues_ReturnNewlySetValue(double newValue)
+        {
+            // Setup
+            var backgroundData = new BackgroundData();
+            var originalNumberOfDecimals = backgroundData.Transparency.NumberOfDecimalPlaces;
+
+            // Call
+            backgroundData.Transparency = (RoundedDouble)newValue;
+
+            // Assert
+            Assert.AreEqual(newValue, backgroundData.Transparency.Value);
+            Assert.AreEqual(originalNumberOfDecimals, backgroundData.Transparency.NumberOfDecimalPlaces);
+        }
+
+        [Test]
+        [SetCulture("nl-NL")]
+        [TestCase(-123.56)]
+        [TestCase(0.0 - 1e-2)]
+        [TestCase(1.0 + 1e-2)]
+        [TestCase(456.876)]
+        [TestCase(double.NaN)]
+        public void Transparency_SetInvalidValue_ThrowArgumentOutOfRangeException(double invalidTransparency)
+        {
+            // Setup
+            var backgroundData = new BackgroundData();
+
+            // Call
+            TestDelegate call = () => backgroundData.Transparency = (RoundedDouble)invalidTransparency;
+
+            // Assert
+            var message = "De transparantie moet in het bereik [0,00, 1,00] liggen.";
+            string paramName = TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentOutOfRangeException>(call, message).ParamName;
+            Assert.AreEqual("value", paramName);
+        }
     }
 }
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