Index: test/Plugins/Wti/Wti.IO.Test/Builders/SoilLayer2DTest.cs
===================================================================
diff -u -r46c2fd882297a1243b82d8cacfbb4fc1881f2157 -r947dc8ecd6e0b674f39bf1a22aef489ec8cc21fa
--- test/Plugins/Wti/Wti.IO.Test/Builders/SoilLayer2DTest.cs	(.../SoilLayer2DTest.cs)	(revision 46c2fd882297a1243b82d8cacfbb4fc1881f2157)
+++ test/Plugins/Wti/Wti.IO.Test/Builders/SoilLayer2DTest.cs	(.../SoilLayer2DTest.cs)	(revision 947dc8ecd6e0b674f39bf1a22aef489ec8cc21fa)
@@ -10,14 +10,14 @@
     public class SoilLayer2DTest
     {
         [Test]
-        public void DefaultConstructor_Always_NotInstantiatedOuterAndInnerLoops()
+        public void DefaultConstructor_Always_NotInstantiatedOuterLoopAndEmptyInnerLoops()
         {
             // Call
             var result = new SoilLayer2D();
 
             // Assert
             Assert.IsNull(result.OuterLoop);
-            Assert.IsNull(result.InnerLoop);
+            CollectionAssert.IsEmpty(result.InnerLoops);
         }
 
         [Test]
@@ -58,5 +58,29 @@
             CollectionAssert.IsEmpty(result);
             Assert.AreEqual(double.MaxValue, bottom);
         }
+
+        [Test]
+        public void AsPipingSoilLayers_WithOuterLoopIntersectingX_ReturnsBottomAndLayerWithTop()
+        {
+            // Setup
+            var layer = new SoilLayer2D
+            {
+                OuterLoop = new HashSet<Point3D>
+                {
+                    new Point3D
+                    {
+                        X = 0.1, Z = new Random(22).NextDouble()
+                    }
+                }
+            };
+            double bottom;
+
+            // Call
+            var result = layer.AsPipingSoilLayers(0.0, out bottom);
+
+            // Assert
+            CollectionAssert.IsEmpty(result);
+            Assert.AreEqual(double.MaxValue, bottom);
+        }
     }
 }
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