Added tests

Tests/Musify.Infrastructure.Tests/JobTestHarness.cs

@@ -0,0 +1,32 @@
+using System.Reflection;
+using Microsoft.Extensions.DependencyInjection;
+using Musify.Application.Contracts;
+using Musify.Application.Tests.Infrastructure;
+
+namespace Musify.Infrastructure.Tests;
+
+internal static class JobTestHarness
+{
+    public static IServiceScopeFactory ScopeFactoryWith(Action<IServiceCollection> configure)
+    {
+        var services = new ServiceCollection();
+        configure(services);
+        return services.BuildServiceProvider().GetRequiredService<IServiceScopeFactory>();
+    }
+
+    public static IServiceScopeFactory WithDatabase(IDatabase database) =>
+        ScopeFactoryWith(s => s.AddSingleton(database));
+
+    public static IServiceScopeFactory WithStorage(IStorageService storage) =>
+        ScopeFactoryWith(s => s.AddSingleton(storage));
+
+    public static Task RunAsync(object job, CancellationToken cancellationToken = default)
+    {
+        var method = job.GetType().GetMethod(
+            "RunAsync",
+            BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public)
+            ?? throw new InvalidOperationException("RunAsync not found on job.");
+
+        return (Task)method.Invoke(job, [cancellationToken])!;
+    }
+}