Added unit testing

Syrette.Tests/ServiceContainerResolutionTests.cs

@@ -0,0 +1,141 @@
+namespace Syrette.Tests;
+
+public class ServiceContainerResolutionTests
+{
+    [Fact]
+    public void GetService_T_resolves_singleton()
+    {
+        var container = new ServiceContainer();
+        container.AddSingleton<ITestService, TestServiceImpl>();
+        var instance = container.GetService<ITestService>();
+        Assert.NotNull(instance);
+        Assert.IsType<TestServiceImpl>(instance);
+    }
+
+    [Fact]
+    public void GetService_T_resolves_transient()
+    {
+        var container = new ServiceContainer();
+        container.AddTransient<ITestServiceB, TestServiceBImpl>();
+        var instance = container.GetService<ITestServiceB>();
+        Assert.NotNull(instance);
+        Assert.IsType<TestServiceBImpl>(instance);
+    }
+
+    [Fact]
+    public void Singleton_returns_same_instance()
+    {
+        var container = new ServiceContainer();
+        container.AddSingleton<ITestService, TestServiceImpl>();
+        var a = container.GetService<ITestService>();
+        var b = container.GetService<ITestService>();
+        Assert.Same(a, b);
+    }
+
+    [Fact]
+    public void Transient_returns_new_instance()
+    {
+        var container = new ServiceContainer();
+        container.AddTransient<ITestServiceB, TestServiceBImpl>();
+        var a = container.GetService<ITestServiceB>();
+        var b = container.GetService<ITestServiceB>();
+        Assert.NotSame(a, b);
+    }
+
+    [Fact]
+    public void GetService_Type_non_generic_resolves()
+    {
+        var container = new ServiceContainer();
+        container.AddSingleton<ITestService, TestServiceImpl>();
+        var instance = container.GetService(typeof(ITestService));
+        Assert.NotNull(instance);
+        Assert.IsType<TestServiceImpl>(instance);
+    }
+
+    [Fact]
+    public void GetService_Type_with_args_resolves()
+    {
+        var container = new ServiceContainer();
+        container.AddTransient<ITestService, TestDeepService>();
+        var instance = container.GetService(typeof(ITestService), new object[] { Guid.NewGuid() });
+        Assert.NotNull(instance);
+    }
+
+    [Fact]
+    public void GetService_T_throws_for_unregistered()
+    {
+        var container = new ServiceContainer();
+        Assert.Throws<InvalidOperationException>(() =>
+            container.GetService<ITestService>());
+    }
+
+    [Fact]
+    public void GetService_Type_throws_for_unregistered()
+    {
+        var container = new ServiceContainer();
+        Assert.Throws<InvalidOperationException>(() =>
+            container.GetService(typeof(ITestService)));
+    }
+
+    [Fact]
+    public void TryGetService_returns_null_for_unregistered()
+    {
+        var container = new ServiceContainer();
+        var result = container.TryGetService(typeof(ITestService));
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void TryGetService_returns_instance_when_registered()
+    {
+        var container = new ServiceContainer();
+        container.AddSingleton<ITestService, TestServiceImpl>();
+        var result = container.TryGetService(typeof(ITestService));
+        Assert.NotNull(result);
+    }
+
+    [Fact]
+    public void Resolve_by_implementation_type_when_not_registered_directly()
+    {
+        var container = new ServiceContainer();
+        container.AddSingleton<ITestService, TestServiceImpl>();
+        var instance = container.GetService(typeof(TestServiceImpl));
+        Assert.NotNull(instance);
+    }
+
+    [Fact]
+    public void Resolution_time_args_override_registration_time_args()
+    {
+        var container = new ServiceContainer();
+        container.AddSingleton<ITestService, TestDeepService>(Guid.Empty);
+        var resolved = container.GetService(typeof(ITestService), new object[] { Guid.NewGuid() });
+        Assert.NotNull(resolved);
+        var deep = (TestDeepService)resolved;
+        Assert.NotEqual(Guid.Empty, deep.Id);
+    }
+
+    [Fact]
+    public void GetServices_returns_all_registered_implementations()
+    {
+        var container = new ServiceContainer();
+        container.AddSingleton<ITestService, TestServiceImpl>();
+        container.AddSingleton<ITestService, TestServiceAlt>();
+        var services = container.GetServices<ITestService>();
+        Assert.Equal(2, services.Count);
+        var types = services.Select(s => s.GetType()).ToList();
+        Assert.Contains(typeof(TestServiceImpl), types);
+        Assert.Contains(typeof(TestServiceAlt), types);
+    }
+
+    [Fact]
+    public void GetServiceTypes_returns_all_implementation_types()
+    {
+        var container = new ServiceContainer();
+        container.AddSingleton<ITestService, TestServiceImpl>();
+        container.AddSingleton<ITestService, TestServiceAlt>();
+        var types = container.GetServiceTypes<ITestService>();
+        Assert.Equal(2, types.Count);
+        Assert.Contains(typeof(TestServiceImpl), types);
+        Assert.Contains(typeof(TestServiceAlt), types);
+    }
+}