feat(DependencyInjector): throw exception in Provide<T> if no provide…

…r exists
jonisavo · May 1, 2022 · 4ccebe5 · 4ccebe5
1 parent caa2e1b
commit 4ccebe5
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Showing 5 changed files with 53 additions and 10 deletions.
diff --git a/Core/DependencyInjector.cs b/Core/DependencyInjector.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using JetBrains.Annotations;
+using UIComponents.Core.Exceptions;
 using UnityEngine;
 
 namespace UIComponents.Core
@@ -72,18 +73,17 @@ private static object CreateInstance(Type dependencyType)
             DependencyDictionary[typeof(T)] = instance;
         }
 
+        [NotNull]
         public T Provide<T>() where T : class
         {
             var type = typeof(T);
+
+            if (!DependencyDictionary.ContainsKey(type))
+                throw new MissingProviderException(type);
 
-            if (DependencyDictionary.ContainsKey(type))
-                return (T) DependencyDictionary[type];
-
-            Debug.LogWarningFormat("Could not get dependency {0}", type.Name);
-
-            return null;
+            return (T) DependencyDictionary[type];
         }
-        
+
         private void PopulateFromDependencyAttributes(IEnumerable<DependencyAttribute> dependencyAttributes)
         {
             foreach (var dependencyAttribute in dependencyAttributes)

diff --git a/Core/Exceptions.meta b/Core/Exceptions.meta
diff --git a/Core/Exceptions/MissingProviderException.cs b/Core/Exceptions/MissingProviderException.cs
@@ -0,0 +1,17 @@
+using System;
+
+namespace UIComponents.Core.Exceptions
+{
+    public class MissingProviderException : Exception
+    {
+        public readonly Type DependencyType;
+
+        public MissingProviderException(Type dependencyType)
+        {
+            DependencyType = dependencyType;
+            Message = $"No provider found for {dependencyType.Name}";
+        }
+
+        public override string Message { get; }
+    }
+}
diff --git a/Core/Exceptions/MissingProviderException.cs.meta b/Core/Exceptions/MissingProviderException.cs.meta
diff --git a/Tests/DependencyInjectorTests.cs b/Tests/DependencyInjectorTests.cs
@@ -1,6 +1,7 @@
 using System;
 using NUnit.Framework;
 using UIComponents.Core;
+using UIComponents.Core.Exceptions;
 
 namespace UIComponents.Tests
 {
@@ -12,6 +13,28 @@ private interface IDependency {}
         public class DependencyOne : IDependency {}
 
         public class DependencyTwo : IDependency {}
+
+        [TestFixture]
+        public class Provide
+        {
+            [Test]
+            public void Returns_Desired_Dependency()
+            {
+                var injector = new DependencyInjector();
+                injector.SetDependency<IDependency>(new DependencyOne());
+                Assert.That(injector.Provide<IDependency>(), Is.InstanceOf<DependencyOne>());
+            }
+
+            [Test]
+            public void Throws_If_No_Provider_Exists()
+            {
+                var injector = new DependencyInjector();
+
+                Assert.Throws<MissingProviderException>(
+                    () => injector.Provide<IDependency>()
+                );
+            }
+        }
 
         [TestFixture]
         public class SetDependency
@@ -22,9 +45,6 @@ public void Switches_The_Dependency()
                 var injector = new DependencyInjector();
 
                 injector.SetDependency<IDependency>(new DependencyOne());
-
-                Assert.That(injector.Provide<IDependency>(), Is.InstanceOf<DependencyOne>());
-
                 injector.SetDependency<IDependency>(new DependencyTwo());
 
                 Assert.That(injector.Provide<IDependency>(), Is.InstanceOf<DependencyTwo>());