general renderer read tests

test/GeneralRendererTest.cs

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+using NUnit.Framework;
+
+using System;
+using System.Collections.Generic;
+
+using Encompass;
+
+namespace Tests
+{
+    public class GeneralRendererTest
+    {
+        struct AComponent : IComponent { }
+
+        public class SingletonRead
+        {
+            static KeyValuePair<Guid, AComponent> result;
+
+            class TestRenderer : GeneralRenderer
+            {
+                public new int Layer { get { return 1; } }
+
+                public override void Render()
+                {
+                    result = ReadComponent<AComponent>();
+                }
+            }
+
+            [Test]
+            public void SingletonComponent()
+            {
+                var worldBuilder = new WorldBuilder();
+                worldBuilder.AddRenderer<TestRenderer>();
+
+                AComponent aComponent;
+
+                var entity = worldBuilder.CreateEntity();
+                var componentID = entity.AddComponent(aComponent);
+
+                var world = worldBuilder.Build();
+
+                world.Update(0.01f);
+                world.Draw();
+
+                Assert.That(result, Is.EqualTo(new KeyValuePair<Guid, AComponent>(componentID, aComponent)));
+            }
+
+            [Test]
+            public void MultipleComponents()
+            {
+                var worldBuilder = new WorldBuilder();
+                worldBuilder.AddRenderer<TestRenderer>();
+
+                AComponent aComponent;
+                AComponent aComponentTwo;
+
+                var entity = worldBuilder.CreateEntity();
+                var componentID = entity.AddComponent(aComponent);
+                var componentTwoID = entity.AddComponent(aComponentTwo);
+                var world = worldBuilder.Build();
+
+                world.Update(0.01f);
+
+                Assert.Throws<InvalidOperationException>(() => world.Draw());
+            }
+        }
+    }
+}