fix(portal): synchronize destination presentation state

tests/AcDream.Core.Tests/World/ProceduralSceneryIdAllocatorTests.cs

@@ -0,0 +1,54 @@
+using AcDream.Core.World;
+
+namespace AcDream.Core.Tests.World;
+
+public sealed class ProceduralSceneryIdAllocatorTests
+{
+    [Fact]
+    public void Base_AlwaysSetsSceneryBitAndAvoidsStabPrefix()
+    {
+        for (uint y = 0; y <= 255; y += 51)
+        for (uint x = 0; x <= 255; x += 51)
+        {
+            uint value = ProceduralSceneryIdAllocator.Base(x, y);
+            Assert.NotEqual(0u, value & 0x80000000u);
+            Assert.NotEqual(0xC0000000u, value & 0xC0000000u);
+        }
+    }
+
+    [Fact]
+    public void MoreThan256SceneryEntriesRemainInOwningLandblockRange()
+    {
+        uint id = ProceduralSceneryIdAllocator.Base(0x12u, 0x36u) + 300u;
+
+        Assert.True(id < ProceduralSceneryIdAllocator.Base(0x12u, 0x37u));
+        Assert.NotEqual(0u, id & 0x80000000u);
+    }
+
+    [Fact]
+    public void MaximumCounterDoesNotAliasAdjacentLandblock()
+    {
+        for (uint y = 0; y < 255; y++)
+        {
+            uint current = ProceduralSceneryIdAllocator.Base(0, y);
+            uint next = ProceduralSceneryIdAllocator.Base(0, y + 1);
+            Assert.True(current + ProceduralSceneryIdAllocator.MaxCounter < next);
+        }
+    }
+
+    [Fact]
+    public void Allocate_AcceptsLastCounterThenFailsBeforeNamespaceWrap()
+    {
+        uint counter = ProceduralSceneryIdAllocator.MaxCounter;
+
+        uint last = ProceduralSceneryIdAllocator.Allocate(0x12u, 0x36u, ref counter);
+
+        Assert.Equal(
+            ProceduralSceneryIdAllocator.Base(0x12u, 0x36u)
+                + ProceduralSceneryIdAllocator.MaxCounter,
+            last);
+        InvalidDataException error = Assert.Throws<InvalidDataException>(
+            () => ProceduralSceneryIdAllocator.Allocate(0x12u, 0x36u, ref counter));
+        Assert.Contains("4096-entry", error.Message, StringComparison.Ordinal);
+    }
+}