Project-M/Assets/_Project/Tests/EditMode/SystemOrderingCycleTests.cs

using NUnit.Framework;
using ProjectM.Server;
using ProjectM.Simulation;
using Unity.Entities;

namespace ProjectM.Tests
{
    /// <summary>
    /// Guards the ComponentSystemSorter "circular dependency" hazard that is INVISIBLE to the rest of the suite:
    /// every other fixture registers a single system then sorts, so a cross-system [UpdateBefore/After] cycle can
    /// never surface — it only throws at world creation in Play. This registers the REAL ordered server-sim set
    /// (every system that participates in an UpdateBefore/After relation, or its constraint is silently ignored)
    /// into one SimulationSystemGroup and sorts, reproducing the Play-time sort headlessly. Only SortSystems runs
    /// (never Update), so a bare world with no entities/singletons suffices.
    /// </summary>
    public class SystemOrderingCycleTests
    {
        [Test]
        public void RunCycleCombatChain_Sorts_Without_A_Dependency_Cycle()
        {
            using var world = new World("OrderCycleGuard");
            var group = world.GetOrCreateSystemManaged<SimulationSystemGroup>();

            void Add<T>() where T : unmanaged, ISystem
                => group.AddSystemToUpdateList(world.GetOrCreateSystem<T>());

            // RPC-receive systems ordered before the run director
            Add<ReadyToggleSystem>();   Add<RouteSelectSystem>();  Add<PortalInteractReceiveSystem>();
            Add<MetaSpendSystem>();     Add<ClassSelectReceiveSystem>(); Add<BoonApplySystem>(); Add<PrepPurchaseSystem>();
            // Run director + the systems ordered around it (the cycle/siege spine is deleted — LANTERN purge)
            Add<RunDirectorSystem>();   Add<RoomFieldSystem>();
            Add<RoomEnemyDirectorSystem>(); Add<BoonOfferSystem>();
            Add<WaveSystem>();
            // Combat sub-chain in the same group
            Add<EnemyAISystem>();       Add<BossAISystem>();
            Add<EnemyProjectileMoveSystem>(); Add<EnemyProjectileDamageSystem>();

            Assert.DoesNotThrow(() => group.SortSystems(),
                "A [UpdateBefore/After] cycle in the run/cycle/combat chain throws here instead of only at Play world-creation.");
        }
    

        [Test]
        public void PredictedCombatChain_Sorts_Without_A_Dependency_Cycle()
        {
            // Phase 1.7 added DashTrailDamageSystem ([UpdateAfter(DashSystem)][UpdateBefore(HealthApplyDamageSystem)])
            // and KillRewardSystem ([UpdateAfter(HealthApplyDamageSystem)]) to the predicted combat chain. A cycle in
            // these [UpdateBefore/After] edges is INVISIBLE to per-system fixtures — it only throws at Play world
            // creation. Co-register the chain and sort to reproduce that headlessly (SortSystems only, never Update).
            using var world = new World("OrderCyclePredicted");
            var group = world.GetOrCreateSystemManaged<SimulationSystemGroup>();
            void Add<T>() where T : unmanaged, ISystem
                => group.AddSystemToUpdateList(world.GetOrCreateSystem<T>());

            Add<StatRecomputeSystem>(); Add<MeleeComboSystem>(); Add<DashSystem>(); Add<DashTrailDamageSystem>();
            Add<AbilityFireSystem>();   Add<ProjectileMoveSystem>(); Add<ProjectileDamageSystem>();
            Add<HealthApplyDamageSystem>(); Add<KillRewardSystem>();

            Assert.DoesNotThrow(() => group.SortSystems(),
                "A cycle in the Phase 1.7 predicted combat chain throws here instead of only at Play world-creation.");
        }
}
}