Adds FeatureListValidator and some tests.

Sharpasonne.Models.Tests/FeatureListValidatorTests.cs

@@ -0,0 +1,40 @@
+using System;
+using System.Collections.Immutable;
+using System.Linq;
+using Optional.Unsafe;
+using Sharpasonne.Models.Features;
+using Xunit;
+
+namespace Sharpasonne.Models.Tests
+{
+    public class FeatureListValidatorTests
+    {
+        [Fact]
+        void Given_EmptyTile_When_CheckingForOverlaps_Then_IsValid()
+        {
+            var featureList = Enumerable.Empty<IFeature>().ToImmutableList();
+            var isValid = new FeatureListValidator().CheckFeaturesDontOverlap(featureList);
+
+            Assert.True(isValid);
+        }
+
+        [Fact]
+        void Given_OverlappingFeaturesTile_When_CheckingForOverlaps_Then_IsNotValid()
+        {
+            var segments = Enumerable.Repeat(Segment.Left, 2)
+                .ToImmutableHashSet();
+            var overlappingFeatures = Enumerable.Repeat(new Field(segments) as IFeature, 2)
+                .ToImmutableList();
+
+            var isValid = new FeatureListValidator().CheckFeaturesDontOverlap(overlappingFeatures);
+
+            Assert.False(isValid);
+        }
+
+        [Fact]
+        void Given_EmptyTile_When_CheckingForFields_Then_AllFields()
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

Sharpasonne.Models/FeatureListValidator.cs

@@ -0,0 +1,28 @@
+using System.Collections.Immutable;
+using System.Linq;
+using JetBrains.Annotations;
+
+namespace Sharpasonne.Models
+{
+    public class FeatureListValidator
+    {
+        public bool IsValid([NotNull] IImmutableList<IFeature> featureList)
+        {
+            var isValid = CheckFeaturesDontOverlap(featureList);
+
+            return isValid;
+        }
+
+        public bool CheckFeaturesDontOverlap(
+            [NotNull] [ItemNotNull] IImmutableList<IFeature> featureList)
+        {
+            var segments = featureList
+                .SelectMany(f => f.Connections)
+                .ToList();
+
+            var distinctSegments = segments.Distinct();
+
+            return segments.Count() == distinctSegments.Count();
+        }
+    }
+}

Sharpasonne.Models/Features/Field.cs

@@ -2,8 +2,13 @@
 
 namespace Sharpasonne.Models.Features
 {
-    class Field : IFeature
+    public class Field : IFeature
     {
+        public Field(IImmutableSet<Segment> connections)
+        {
+            Connections = connections;
+        }
+
         public IImmutableSet<Segment> Connections { get; }
     }
 }

Sharpasonne.Models/TileBuilder.cs

@@ -3,29 +3,22 @@
 using System.Linq;
 using JetBrains.Annotations;
 using Optional;
-using Sharpasonne.Models;
 
-namespace Sharpasonne
+namespace Sharpasonne.Models
 {
     public class TileBuilder
     {
         public Option<Tile> CreateTile([NotNull] IEnumerable<IFeature> features)
         {
             var featureList = features as IImmutableList<IFeature> ?? features.ToImmutableList();
 
-            if (IsValid(featureList))
+            if (new FeatureListValidator().IsValid(featureList))
             {
                 var tile = new Tile(featureList);
                 return Option.Some(tile);
             }
 
             return Option.None<Tile>();
         }
-
-        private bool IsValid([NotNull] IImmutableList<IFeature> featureList)
-        {
-            // TODO: It.
-            return true;
-        }
     }
 }