From 7413e25eec38666f1bdd91bf1305b5d1183be898 Mon Sep 17 00:00:00 2001
From: Joni Savolainen <joni@savolainen.io>
Date: Thu, 21 Sep 2023 20:50:27 +0300
Subject: [PATCH] feat: add abstract DependencyConsumer base class for DI
 consumers

---
 .../DependencyConsumerTests.cs                | 89 +++++++++++++++++++
 .../DependencyConsumerTests.cs.meta           |  3 +
 .../DependencyAttribute.cs                    |  1 +
 .../DependencyInjection/DependencyConsumer.cs | 67 ++++++++++++++
 .../DependencyConsumer.cs.meta                |  3 +
 Assets/UIComponents/Core/UIComponent.cs       |  1 +
 6 files changed, 164 insertions(+)
 create mode 100644 Assets/UIComponents.Tests/DependencyConsumerTests.cs
 create mode 100644 Assets/UIComponents.Tests/DependencyConsumerTests.cs.meta
 create mode 100644 Assets/UIComponents/Core/DependencyInjection/DependencyConsumer.cs
 create mode 100644 Assets/UIComponents/Core/DependencyInjection/DependencyConsumer.cs.meta

diff --git a/Assets/UIComponents.Tests/DependencyConsumerTests.cs b/Assets/UIComponents.Tests/DependencyConsumerTests.cs
new file mode 100644
index 00000000..e3e84fa0
--- /dev/null
+++ b/Assets/UIComponents.Tests/DependencyConsumerTests.cs
@@ -0,0 +1,89 @@
+using NUnit.Framework;
+using UIComponents.DependencyInjection;
+using UIComponents.Testing;
+
+namespace UIComponents.Tests
+{
+    [TestFixture]
+    public partial class DependencyConsumerTests
+    {
+        private interface IStringDependency
+        {
+            string GetValue();
+        }
+        
+        private interface IIntDependency
+        {
+            int GetValue();
+        }
+
+        public class StringProvider : IStringDependency
+        {
+            public string GetValue() => "Hello world";
+        }
+
+        public class EmptyStringProvider : IStringDependency
+        {
+            public string GetValue() => "";
+        }
+
+        [Dependency(typeof(IStringDependency), provide: typeof(StringProvider))]
+        private partial class StringDependencyConsumer : DependencyConsumer
+        {
+            [Provide]
+            public IStringDependency StringDependency;
+
+            public bool TryProvideStringDependency(out IStringDependency dependency)
+            {
+                return TryProvide(out dependency);
+            }
+            
+            public bool TryProvideIntDependency(out IIntDependency dependency)
+            {
+                return TryProvide(out dependency);
+            }
+        }
+
+        [Dependency(typeof(IStringDependency), provide: typeof(EmptyStringProvider))]
+        private partial class EmptyStringDependencyConsumer : StringDependencyConsumer {}
+
+        [Test]
+        public void The_Correct_Class_Is_Provided_To_StringDependencyConsumer()
+        {
+            var component = new StringDependencyConsumer();
+            Assert.That(component.StringDependency, Is.InstanceOf<StringProvider>());
+        }
+        
+        [Test]
+        public void The_Correct_Class_Is_Provided_To_EmptyStringDependencyConsumer()
+        {
+            var component = new EmptyStringDependencyConsumer();
+            Assert.That(component.StringDependency, Is.InstanceOf<EmptyStringProvider>());
+        }
+
+        [Test]
+        public void TryProvide_Works_For_EmptyStringDependencyConsumer()
+        {
+            var component = new EmptyStringDependencyConsumer();
+            var couldProvideStringDependency = component.TryProvideStringDependency(out var stringDependency);
+            var couldProvideIntDependency = component.TryProvideIntDependency(out var intDependency);
+            
+            Assert.That(couldProvideStringDependency, Is.True);
+            Assert.That(stringDependency, Is.InstanceOf<EmptyStringProvider>());
+            Assert.That(couldProvideIntDependency, Is.False);
+            Assert.That(intDependency, Is.Null);
+        }
+
+        [Test]
+        public void TestBed_Works_With_DependencyConsumers()
+        {
+            var stringProvider = new StringProvider();
+
+            var component = new TestBed<StringDependencyConsumer>()
+                .WithSingleton<IStringDependency>(stringProvider)
+                .Instantiate();
+            
+            Assert.That(component.StringDependency, Is.SameAs(stringProvider));
+        }
+    }
+}
\ No newline at end of file
diff --git a/Assets/UIComponents.Tests/DependencyConsumerTests.cs.meta b/Assets/UIComponents.Tests/DependencyConsumerTests.cs.meta
new file mode 100644
index 00000000..1bb56b04
--- /dev/null
+++ b/Assets/UIComponents.Tests/DependencyConsumerTests.cs.meta
@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: 1b2ead16350643ff8b3cc2d4a8ba401c
+timeCreated: 1695317338
\ No newline at end of file
diff --git a/Assets/UIComponents/Core/DependencyInjection/DependencyAttribute.cs b/Assets/UIComponents/Core/DependencyInjection/DependencyAttribute.cs
index 55a3582c..efde4757 100644
--- a/Assets/UIComponents/Core/DependencyInjection/DependencyAttribute.cs
+++ b/Assets/UIComponents/Core/DependencyInjection/DependencyAttribute.cs
@@ -10,6 +10,7 @@ namespace UIComponents
     /// </summary>
     /// <seealso cref="UIComponent"/>
     /// <seealso cref="IDependencyConsumer"/>
+    /// <seealso cref="DependencyConsumer"/>
     [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Assembly, AllowMultiple = true, Inherited = true)]
     [ExcludeFromCoverage]
     [BaseTypeRequired(typeof(IDependencyConsumer))]
diff --git a/Assets/UIComponents/Core/DependencyInjection/DependencyConsumer.cs b/Assets/UIComponents/Core/DependencyInjection/DependencyConsumer.cs
new file mode 100644
index 00000000..e99cede5
--- /dev/null
+++ b/Assets/UIComponents/Core/DependencyInjection/DependencyConsumer.cs
@@ -0,0 +1,67 @@
+using System;
+using System.Collections.Generic;
+
+namespace UIComponents.DependencyInjection
+{
+    /// <summary>
+    /// An abstract base class for classes which want to access
+    /// UIComponents's dependency injection system.
+    /// <example>
+    /// <code>
+    /// [Dependency(typeof(IMyDependency), provide: typeof(MyDependency))]
+    /// public class MyClass : DependencyConsumer
+    /// {
+    ///     [Provide]
+    ///     private IMyDependency _myDependency;
+    /// }
+    /// </code>
+    /// </example>
+    /// <seealso cref="DependencyAttribute"/>
+    /// <seealso cref="ProvideAttribute"/>
+    /// </summary>
+    public abstract class DependencyConsumer : IDependencyConsumer
+    {
+        private static readonly IDependency[] EmptyDependencies = Array.Empty<IDependency>();
+
+        private readonly DependencyInjector _dependencyInjector;
+
+        internal DependencyConsumer()
+        {
+            DiContext.Current.RegisterConsumer(this);
+            _dependencyInjector = DiContext.Current.GetInjector(GetType());
+            
+            // ReSharper disable once VirtualMemberCallInConstructor
+            UIC_PopulateProvideFields();
+        }
+        
+        /// <summary>
+        /// Returns a dependency. Throws a <see cref="MissingProviderException"/>
+        /// if the dependency can not be provided.
+        /// </summary>
+        /// <typeparam name="T">Dependency type</typeparam>
+        /// <exception cref="MissingProviderException">
+        /// Thrown if the dependency can not be provided
+        /// </exception>
+        /// <returns>Dependency instance</returns>
+        protected T Provide<T>() where T : class
+        {
+            return _dependencyInjector.Provide<T>();
+        }
+
+        /// <summary>
+        /// Attempts to provide a dependency. Returns whether
+        /// the dependency could be provided.
+        /// </summary>
+        /// <param name="instance">Dependency instance</param>
+        /// <typeparam name="T">Dependency type</typeparam>
+        /// <returns>Whether the dependency could be fetched</returns>
+        protected bool TryProvide<T>(out T instance) where T : class
+        {
+            return _dependencyInjector.TryProvide(out instance);
+        }
+
+        public virtual IEnumerable<IDependency> GetDependencies() => EmptyDependencies;
+        
+        protected virtual void UIC_PopulateProvideFields() {}
+    }
+}
\ No newline at end of file
diff --git a/Assets/UIComponents/Core/DependencyInjection/DependencyConsumer.cs.meta b/Assets/UIComponents/Core/DependencyInjection/DependencyConsumer.cs.meta
new file mode 100644
index 00000000..5dc2755a
--- /dev/null
+++ b/Assets/UIComponents/Core/DependencyInjection/DependencyConsumer.cs.meta
@@ -0,0 +1,3 @@
+fileFormatVersion: 2
+guid: cf339915dc37467db4c9e9eff3f092e0
+timeCreated: 1695316641
\ No newline at end of file
diff --git a/Assets/UIComponents/Core/UIComponent.cs b/Assets/UIComponents/Core/UIComponent.cs
index 2cecc297..f38c7088 100644
--- a/Assets/UIComponents/Core/UIComponent.cs
+++ b/Assets/UIComponents/Core/UIComponent.cs
@@ -68,6 +68,7 @@ protected UIComponent()
             _dependencyInjector = DiContext.Current.GetInjector(GetType());
             AssetResolver = Provide<IAssetResolver>();
             Logger = Provide<ILogger>();
+            // ReSharper disable once VirtualMemberCallInConstructor
             UIC_PopulateProvideFields();
 
             DependencySetupProfilerMarker.End();