better error message when component is not found on entity

encompass-cs/Collections/TypedComponentStore.cs

@@ -22,6 +22,7 @@ namespace Encompass
 
         public TComponent Get(int entityID)
         {
+            if (!store.ContainsKey(entityID)) { throw new Exceptions.NoComponentOfTypeOnEntityException("No component of type {0} exists on Entity with ID {1}", typeof(TComponent), entityID); }
             return store[entityID];
         }
 

encompass-cs/Exceptions/ComponentNotFoundException.cs

@@ -1,12 +0,0 @@
-using System;
-
-namespace Encompass.Exceptions
-{
-    public class ComponentNotFoundException : Exception
-    {
-        public ComponentNotFoundException(
-            string format,
-            params object[] args
-        ) : base(string.Format(format, args)) { }
-    }
-}

encompass-cs/Exceptions/ComponentTypeMismatchException.cs

@@ -1,12 +0,0 @@
-using System;
-
-namespace Encompass.Exceptions
-{
-    public class ComponentTypeMismatchException : Exception
-    {
-        public ComponentTypeMismatchException(
-            string format,
-            params object[] args
-        ) : base(string.Format(format, args)) { }
-    }
-}

encompass-cs/Exceptions/RepeatUpdateComponentException.cs

@@ -1,12 +0,0 @@
-using System;
-
-namespace Encompass.Exceptions
-{
-    public class RepeatUpdateComponentException : Exception
-    {
-        public RepeatUpdateComponentException(
-            string format,
-            params object[] args
-        ) : base(string.Format(format, args)) { }
-    }
-}

test/EngineTest.cs

@@ -833,7 +833,7 @@ namespace Tests
             worldBuilder.AddEngine(new ReadEntityByComponentTypeEngine());
 
             var entity = worldBuilder.CreateEntity();
-            worldBuilder.SetComponent(entity, new MockComponent { });
+            worldBuilder.SetComponent(entity, new MockComponent());
 
             var world = worldBuilder.Build();
             world.Update(0.01);
@@ -841,7 +841,69 @@ namespace Tests
             entity.Should().BeEquivalentTo(readEntity);
         }
 
+        struct MockComponentB : IComponent
+        {
+            public MockComponentB(int value)
+            {
+                this.value = value;
+            }
 
+            int value;
+        }
+
+        static MockComponentB getComponentResult;
+
+        [Reads(typeof(MockComponent), typeof(MockComponentB))]
+        class GetComponentEngine : Engine
+        {
+            public override void Update(double dt)
+            {
+                getComponentResult = GetComponent<MockComponentB>(ReadEntity<MockComponent>());
+            }
+        }
+
+        [Test]
+        public void GetComponent()
+        {
+            var worldBuilder = new WorldBuilder();
+
+            var entity = worldBuilder.CreateEntity();
+
+            worldBuilder.SetComponent(entity, new MockComponent());
+            worldBuilder.SetComponent(entity, new MockComponentB(3));
+            worldBuilder.AddEngine(new GetComponentEngine());
+
+            var world = worldBuilder.Build();
+
+            world.Update(0.01);
+
+            getComponentResult.Should().BeEquivalentTo(new MockComponentB(3));
+        }
+
+        [Reads(typeof(MockComponent), typeof(MockComponentB))]
+        class GetComponentExceptionEngine : Engine
+        {
+            public override void Update(double dt)
+            {
+                foreach (var entity in ReadEntities<MockComponent>())
+                {
+                    GetComponent<MockComponentB>(entity);
+                }
+            }
+        }
+
+        [Test]
+        public void GetComponentWhenComponentIsNotOnEntity()
+        {
+            var worldBuilder = new WorldBuilder();
+            worldBuilder.AddEngine(new GetComponentExceptionEngine());
+
+            var entity = worldBuilder.CreateEntity();
+            worldBuilder.SetComponent(entity, new MockComponent());
+
+            var world = worldBuilder.Build();
+            Assert.Throws<Encompass.Exceptions.NoComponentOfTypeOnEntityException>(() => world.Update(0.01));
+        }
 
         static Entity[] readEntities;
 
@@ -1606,6 +1668,25 @@ namespace Tests
                 Assert.DoesNotThrow(() => world.Update(0.2));
                 Assert.DoesNotThrow(() => world.Update(0.25));
             }
+
+            [Test]
+            public void DestroyedEntitiesAreRemovedFromTracking()
+            {
+                var worldBuilder = new WorldBuilder();
+
+                var entity = worldBuilder.CreateEntity();
+                worldBuilder.SetComponent(entity, new MockComponent());
+
+                worldBuilder.AddEngine(new DestroyWithEngine());
+                worldBuilder.AddEngine(new ReadEntitiesWithComponentTypeEngine());
+
+                var world = worldBuilder.Build();
+
+                world.Update(0.01);
+                world.Update(0.01);
+
+                readEntities.Should().BeEmpty();
+            }
         }
     }
 }