Test.cs

using Autofac;

namespace AutofacFactoryGenerator;

public class FactoryTests
{
    public class Dependency { }
    public class Startable(Func<Dependency> factory): IStartable
    {
        public void Start()
        {
            Assert.NotNull(factory());   
        }
    }

    private static IContainer BuildContainer()
    {
        var builder = new ContainerBuilder();
        builder.RegisterType<Dependency>();
        var container = builder.Build();
        return container;
    }

    [Fact]
    public void LifetimeWithoutStartable()
    {
        var container = BuildContainer();

        using var lifetimeScope1 = container.BeginLifetimeScope();
        using var lifetimeScope2 = container.BeginLifetimeScope();
        using var lifetimeScope3 = container.BeginLifetimeScope();

        var factory1 = lifetimeScope1.Resolve<Func<Dependency>>();
        var factory2 = lifetimeScope2.Resolve<Func<Dependency>>();
        var factory3 = lifetimeScope2.Resolve<Func<Dependency>>();

        var d1 = factory1();
        var d2 = factory2();
        var d3 = factory3();

        Assert.NotSame(d1, d2);
        Assert.NotSame(d1, d3);
        Assert.NotSame(d2, d3);
    }

    [Fact]
    public void LifetimeWithStartable()
    {
        var container = BuildContainer();

        static void WithStartable(ContainerBuilder c) => c.RegisterType<Startable>().As<IStartable>();

        using var lifetimeScope1 = container.BeginLifetimeScope(WithStartable);
        using var lifetimeScope2 = container.BeginLifetimeScope(WithStartable);
        using var lifetimeScope3 = container.BeginLifetimeScope(WithStartable);

        var factory1 = lifetimeScope1.Resolve<Func<Dependency>>();
        var factory2 = lifetimeScope2.Resolve<Func<Dependency>>();
        var factory3 = lifetimeScope3.Resolve<Func<Dependency>>();

        var d1 = factory1();
        var d2 = factory2();
        var d3 = factory3();

        Assert.NotSame(d1, d2);
        Assert.NotSame(d1, d3);
        Assert.NotSame(d2, d3);
    }
}