read component tests

test/EngineTest.cs

@@ -3,13 +3,15 @@ using System.Linq;
 
 using Encompass;
 using System.Collections.Generic;
+using System;
 
 namespace Tests {
     public class EngineTest
     {
         static IEnumerable<MockComponent> components;
+        static MockComponent component;
 
-        public class TestEngine : Engine
+        public class ReadComponentsTestEngine : Engine
         {
             public override void Update(float dt)
             {
@@ -17,11 +19,19 @@ namespace Tests {
             }
         }
 
+        public class ReadComponentTestEngine : Engine
+        {
+            public override void Update(float dt)
+            {
+                component = this.ReadComponent<MockComponent>();
+            }
+        }
+
         [Test]
         public void ReadComponents()
         {
             var worldBuilder = new WorldBuilder();
-            worldBuilder.AddEngine<TestEngine>();
+            worldBuilder.AddEngine<ReadComponentsTestEngine>();
 
             var entity = worldBuilder.CreateEntity();
 
@@ -43,5 +53,50 @@ namespace Tests {
             Assert.Contains(mockComponent, components.ToList());
             Assert.Contains(mockComponentB, components.ToList());
         }
+
+        [Test]
+        public void ReadComponent()
+        {
+            var worldBuilder = new WorldBuilder();
+            worldBuilder.AddEngine<ReadComponentTestEngine>();
+
+            var entity = worldBuilder.CreateEntity();
+
+            MockComponent mockComponent;
+            mockComponent.myInt = 0;
+            mockComponent.myString = "hello";
+
+            entity.AddComponent(mockComponent);
+
+            var world = worldBuilder.Build();
+
+            world.Update(0.01f);
+
+            Assert.AreEqual(mockComponent, component);
+        }
+
+        [Test]
+        public void ReadComponentWhenMultipleComponents()
+        {
+            var worldBuilder = new WorldBuilder();
+            worldBuilder.AddEngine<ReadComponentTestEngine>();
+
+            var entity = worldBuilder.CreateEntity();
+
+            MockComponent mockComponent;
+            mockComponent.myInt = 0;
+            mockComponent.myString = "hello";
+
+            MockComponent mockComponentB;
+            mockComponentB.myInt = 1;
+            mockComponentB.myString = "howdy";
+
+            entity.AddComponent(mockComponent);
+            entity.AddComponent(mockComponentB);
+
+            var world = worldBuilder.Build();
+
+            Assert.Throws<InvalidOperationException>(() => world.Update(0.01f));
+        }
     }
 }