Index: test/Plugins/Wti/Wti.IO.Test/Builders/SoilLayer2DTest.cs
===================================================================
diff -u -r947dc8ecd6e0b674f39bf1a22aef489ec8cc21fa -r2423a70958e7fecfc92afa462c34194cc695a81e
--- test/Plugins/Wti/Wti.IO.Test/Builders/SoilLayer2DTest.cs	(.../SoilLayer2DTest.cs)	(revision 947dc8ecd6e0b674f39bf1a22aef489ec8cc21fa)
+++ test/Plugins/Wti/Wti.IO.Test/Builders/SoilLayer2DTest.cs	(.../SoilLayer2DTest.cs)	(revision 2423a70958e7fecfc92afa462c34194cc695a81e)
@@ -3,7 +3,9 @@
 using System.Linq;
 using NUnit.Framework;
 using Wti.Data;
+using Wti.Data.TestUtil;
 using Wti.IO.Builders;
+using Wti.IO.Properties;
 
 namespace Wti.IO.Test.Builders
 {
@@ -63,24 +65,352 @@
         public void AsPipingSoilLayers_WithOuterLoopIntersectingX_ReturnsBottomAndLayerWithTop()
         {
             // Setup
+            var expectedZ = new Random(22).NextDouble();
             var layer = new SoilLayer2D
             {
                 OuterLoop = new HashSet<Point3D>
                 {
                     new Point3D
                     {
-                        X = 0.1, Z = new Random(22).NextDouble()
+                        X = -0.1, Z = expectedZ
+                    },
+                    new Point3D
+                    {
+                        X = 0.1, Z = expectedZ
                     }
                 }
             };
             double bottom;
 
             // Call
-            var result = layer.AsPipingSoilLayers(0.0, out bottom);
+            var result = layer.AsPipingSoilLayers(0.0, out bottom).ToArray();
 
             // Assert
-            CollectionAssert.IsEmpty(result);
-            Assert.AreEqual(double.MaxValue, bottom);
+            Assert.AreEqual(1, result.Length);
+            Assert.AreEqual(expectedZ, bottom);
+            Assert.AreEqual(expectedZ, result[0].Top);
         }
+
+        [Test]
+        public void AsPipingSoilLayers_OuterLoopComplex_ReturnsTwoLayers()
+        {
+            // Setup
+            var outerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "..1..2..",
+                "........",
+                "..8.7...",
+                "..5.6...",
+                "..4..3..",
+                "........"));
+
+            var layer = new SoilLayer2D
+            {
+                OuterLoop = outerLoop
+            };
+
+            // Call
+            double bottom;
+            var result = layer.AsPipingSoilLayers(3.5, out bottom).ToArray();
+
+            // Assert
+            Assert.AreEqual(2, result.Length);
+            Assert.AreEqual(1.0, bottom);
+            CollectionAssert.AreEquivalent(new[] { 5.0, 2.0 }, result.Select(rl => rl.Top));
+        }
+
+        [Test]
+        public void AsPipingSoilLayers_OuterLoopInnerLoopSimple_ReturnsTwoLayers()
+        {
+            // Setup
+            var outerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine, 
+                "6",
+                "..1..2..",
+                "........",
+                "........",
+                "........",
+                "........",
+                "..4..3.."));
+
+            var innerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "........",
+                "...12...",
+                "........",
+                "........",
+                "...43...",
+                "........"));
+
+            var layer = new SoilLayer2D
+            {
+                OuterLoop = outerLoop,
+                InnerLoops =
+                {
+                    innerLoop
+                }
+            };
+
+            // Call
+            double bottom;
+            var result = layer.AsPipingSoilLayers(3.5, out bottom).ToArray();
+
+            // Assert
+            Assert.AreEqual(2, result.Length);
+            Assert.AreEqual(0, bottom);
+            CollectionAssert.AreEquivalent(new [] {5.0, 1.0}, result.Select(rl => rl.Top));
+        }
+
+        [Test]
+        public void AsPipingSoilLayers_OuterLoopInnerLoopComplex_ReturnsThreeLayers()
+        {
+            // Setup
+            var outerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "..1..2..",
+                "........",
+                "........",
+                "........",
+                "........",
+                "..4..3.."));
+
+            var innerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "........",
+                "...1.2..",
+                "...87...",
+                "...56...",
+                "...4.3..",
+                "........"));
+
+            var layer = new SoilLayer2D
+            {
+                OuterLoop = outerLoop,
+                InnerLoops =
+                {
+                    innerLoop
+                }
+            };
+
+            // Call
+            double bottom;
+            var result = layer.AsPipingSoilLayers(3.5, out bottom).ToArray();
+
+            // Assert
+            Assert.AreEqual(3, result.Length);
+            Assert.AreEqual(0, bottom);
+            CollectionAssert.AreEquivalent(new[] { 5.0, 3.0, 1.0 }, result.Select(rl => rl.Top));
+        }
+
+        [Test]
+        public void AsPipingSoilLayers_OuterLoopMultipleInnerLoops_ReturnsThreeLayers()
+        {
+            // Setup
+            var outerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "..1..2..",
+                "........",
+                "........",
+                "........",
+                "........",
+                "..4..3.."));
+
+            var innerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "........",
+                "...12...",
+                "...43...",
+                "........",
+                "........",
+                "........"));
+
+            var innerLoop2 = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "........",
+                "........",
+                "........",
+                "........",
+                "...12...",
+                "........"));
+
+            var layer = new SoilLayer2D
+            {
+                OuterLoop = outerLoop,
+                InnerLoops =
+                {
+                    innerLoop,
+                    innerLoop2
+                }
+            };
+
+            // Call
+            double bottom;
+            var result = layer.AsPipingSoilLayers(3.5, out bottom).ToArray();
+
+            // Assert
+            Assert.AreEqual(3, result.Length);
+            Assert.AreEqual(0, bottom);
+            CollectionAssert.AreEquivalent(new[] { 5.0, 3.0, 1.0 }, result.Select(rl => rl.Top));
+        }
+
+        [Test]
+        public void AsPipingSoilLayers_OuterLoopOverlappingInnerLoop_ReturnsOneLayer()
+        {
+            // Setup
+            var outerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "..1..2..",
+                "........",
+                "........",
+                "........",
+                ".4....3.",
+                "........"));
+
+            var innerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "........",
+                "........",
+                "........",
+                "...12...",
+                "........",
+                "...43..."));
+
+            var layer = new SoilLayer2D
+            {
+                OuterLoop = outerLoop,
+                InnerLoops =
+                {
+                    innerLoop
+                }
+            };
+
+            // Call
+            double bottom;
+            var result = layer.AsPipingSoilLayers(3.5, out bottom).ToArray();
+
+            // Assert
+            Assert.AreEqual(1, result.Length);
+            Assert.AreEqual(2.0, bottom);
+            CollectionAssert.AreEquivalent(new[] { 5.0 }, result.Select(rl => rl.Top));
+        }
+
+        [Test]
+        public void AsPipingSoilLayers_OuterLoopOverlappingInnerLoopsFirstInnerLoopNotOverBottom_ReturnsOneLayer()
+        {
+            // Setup
+            var outerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "..1..2..",
+                "........",
+                "........",
+                "........",
+                ".4....3.",
+                "........"));
+
+            var innerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "........",
+                "........",
+                "...12...",
+                "........",
+                "........",
+                "...43..."));
+
+            var innerLoop2 = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "........",
+                "...12...",
+                "........",
+                "...43...",
+                "........",
+                "........"));
+
+            var layer = new SoilLayer2D
+            {
+                OuterLoop = outerLoop,
+                InnerLoops =
+                {
+                    innerLoop2,
+                    innerLoop
+                }
+            };
+
+            // Call
+            double bottom;
+            var result = layer.AsPipingSoilLayers(3.5, out bottom).ToArray();
+
+            // Assert
+            Assert.AreEqual(1, result.Length);
+            Assert.AreEqual(4.0, bottom);
+            CollectionAssert.AreEquivalent(new[] { 5.0 }, result.Select(rl => rl.Top));
+        }
+
+        [Test]
+        public void AsPipingSoilLayers_OuterLoopVerticalAtX_ThrowsException()
+        {
+            // Setup
+            var atX = 2.0;
+            var outerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "..1..2..",
+                "........",
+                "........",
+                "........",
+                "........",
+                "..4..3.."));
+
+            var layer = new SoilLayer2D
+            {
+                OuterLoop = outerLoop
+            };
+
+            // Call
+            double bottom;
+            TestDelegate test = () => layer.AsPipingSoilLayers(atX, out bottom);
+
+            // Assert
+            var exception = Assert.Throws<SoilLayer2DConversionException>(test);
+            Assert.AreEqual(String.Format(Resources.Error_CanNotDetermine1DProfileWithVerticalSegmentsAtX, atX), exception.Message);
+        }
+
+        [Test]
+        public void AsPipingSoilLayers_InnerLoopVerticalAtX_ThrowsException()
+        {
+            // Setup
+            var atX = 3.0;
+            var outerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "..1..2..",
+                "........",
+                "........",
+                "........",
+                "........",
+                "..4..3.."));
+
+            var innerLoop = PointCollectionHelper.CreateFromString(String.Join(Environment.NewLine,
+                "6",
+                "........",
+                "...1.2..",
+                "........",
+                "........",
+                "...4.3..",
+                "........"));
+
+            var layer = new SoilLayer2D
+            {
+                OuterLoop = outerLoop,
+                InnerLoops =
+                {
+                    innerLoop
+                }
+            };
+
+            // Call
+            double bottom;
+            TestDelegate test = () => layer.AsPipingSoilLayers(atX, out bottom);
+
+            // Assert
+            var exception = Assert.Throws<SoilLayer2DConversionException>(test);
+            Assert.AreEqual(String.Format(Resources.Error_CanNotDetermine1DProfileWithVerticalSegmentsAtX, atX), exception.Message);
+        }
     }
 }
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