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

using NUnit.Framework;
using ProjectM.Simulation;
using Unity.Mathematics;

namespace ProjectM.Tests
{
    /// <summary>
    /// Pure tests for <see cref="BuildPreviewMath"/> — the client build-ghost validity (in-plot, unoccupied,
    /// affordable) that mirrors the server's authoritative BuildPlaceSystem check, colouring the ground ghost
    /// green (valid) vs red (the first failing reason).
    /// </summary>
    public class BuildPreviewMathTests
    {
        static BaseAnchor Anchor() => new BaseAnchor
        {
            AnchorPos = new float3(0, 0, 0),
            GridOrigin = new float3(0, 0, 0),
            CellSize = 1f,
            GridDims = new int2(8, 8),
        };

        [Test]
        public void InPlot_Unoccupied_Affordable_IsValid()
        {
            Assert.AreEqual(BuildPreviewMath.Valid,
                BuildPreviewMath.Evaluate(Anchor(), new int2(3, 3), occupied: false, have: 50, cost: 20));
        }

        [Test]
        public void OutOfPlot_Reported_First()
        {
            Assert.AreEqual(BuildPreviewMath.OutOfPlot,
                BuildPreviewMath.Evaluate(Anchor(), new int2(99, 0), occupied: true, have: 0, cost: 999),
                "Out-of-plot is reported before occupancy / cost.");
            Assert.AreEqual(BuildPreviewMath.OutOfPlot,
                BuildPreviewMath.Evaluate(Anchor(), new int2(-1, 3), occupied: false, have: 50, cost: 10));
        }

        [Test]
        public void Occupied_Cell_IsBlocked()
        {
            Assert.AreEqual(BuildPreviewMath.Occupied,
                BuildPreviewMath.Evaluate(Anchor(), new int2(3, 3), occupied: true, have: 50, cost: 10));
        }

        [Test]
        public void Unaffordable_When_Have_Below_Cost_Exact_Funds_Ok()
        {
            Assert.AreEqual(BuildPreviewMath.Unaffordable,
                BuildPreviewMath.Evaluate(Anchor(), new int2(3, 3), occupied: false, have: 5, cost: 20));
            Assert.AreEqual(BuildPreviewMath.Valid,
                BuildPreviewMath.Evaluate(Anchor(), new int2(3, 3), occupied: false, have: 20, cost: 20));
        }
    }
}