1 files changed, 47 insertions, 0 deletions
diff --git a/src/LivingVillage.Desktop.Tests/MapGenTests.fs b/src/LivingVillage.Desktop.Tests/MapGenTests.fs
index f426a8a..6486dd7 100644
--- a/src/LivingVillage.Desktop.Tests/MapGenTests.fs
+++ b/src/LivingVillage.Desktop.Tests/MapGenTests.fs
@@ -298,6 +298,53 @@ type MapGenTests () =
         Assert.AreEqual<int64>(6042052L, checksum (MapGen.generateWithSize 64 48 (uint64 4242)))
         Assert.AreEqual<int64>(1284656962L, checksum (MapGen.generateWithSize 256 192 (uint64 4242)))
 
+    // ---- P26：河岸装饰（护岸石垒/芦苇/垂柳）仅大图、落在岸格且不挡通行 ----
+
+    [<TestMethod>]
+    member _.RiverDecorationsOnlyEnabledOnLargeMaps () =
+        Assert.IsFalse((MapGen.paramsForSize 64 48 (uint64 1)).RiverDecorations)
+        Assert.IsFalse((MapGen.paramsForSize 256 192 (uint64 1)).RiverDecorations)
+        Assert.IsTrue((MapGen.paramsForSize 512 384 (uint64 1)).RiverDecorations)
+        Assert.AreEqual<int>(0, (MapGen.generateWithSize 64 48 (uint64 4242)).Decorations.Length)
+        Assert.AreEqual<int>(0, (MapGen.generateWithSize 256 192 (uint64 4242)).Decorations.Length)
+
+    [<TestMethod>]
+    member _.RiverbankDecorationsSitOnBanksAndNeverBlockPathsOrBridges () =
+        let map = MapGen.generateWithSize 512 384 (uint64 4242)
+        Assert.IsTrue(map.Decorations.Length > 0, "512x384 must place riverbank decorations")
+        let pathSet = System.Collections.Generic.HashSet<int>(map.Paths |> List.map (fun (x, y) -> y * map.Width + x))
+        let bridgeSet = System.Collections.Generic.HashSet<int>(map.Bridges |> List.map (fun (x, y) -> y * map.Width + x))
+        let water x y = map.Tiles.[y * map.Width + x] = int MapGen.GroundTile.Water
+        let inCore x y = x >= map.Core.MinX && x <= map.Core.MaxX && y >= map.Core.MinY && y <= map.Core.MaxY
+        for decoration in map.Decorations do
+            let footprint =
+                match decoration.Kind with
+                | MapGen.Willow -> [ decoration.Y; decoration.Y + 1 ]
+                | _ -> [ decoration.Y ]
+            for y in footprint do
+                let i = y * map.Width + decoration.X
+                Assert.AreNotEqual<int>(int MapGen.GroundTile.Water, map.Tiles.[i], "decoration must sit on land")
+                Assert.IsFalse(pathSet.Contains i, "decoration must not block a path tile")
+                Assert.IsFalse(bridgeSet.Contains i, "decoration must not block a bridge tile")
+                Assert.IsFalse(inCore decoration.X y, "decoration must stay outside the core")
+            // Bank adjacency: at least one footprint tile must touch the river orthogonally.
+            let touchesWater =
+                footprint
+                |> List.exists (fun y ->
+                    [ (decoration.X + 1, y); (decoration.X - 1, y); (decoration.X, y + 1); (decoration.X, y - 1) ]
+                    |> List.exists (fun (nx, ny) ->
+                        nx >= 0 && nx < map.Width && ny >= 0 && ny < map.Height && water nx ny))
+            Assert.IsTrue(touchesWater, "decoration must line the riverbank, not float inland")
+
+    [<TestMethod>]
+    member _.LargeMapRiverDecorationsAreDeterministic () =
+        let a = MapGen.generateWithSize 512 384 (uint64 4242)
+        let b = MapGen.generateWithSize 512 384 (uint64 4242)
+        Assert.IsTrue(a.Decorations = b.Decorations)
+        Assert.AreEqual<string>(MapGen.serialize a, MapGen.serialize b)
+        let c = MapGen.generateWithSize 512 384 (uint64 7)
+        Assert.AreNotEqual<string>(MapGen.serialize a, MapGen.serialize c)
+
     [<TestMethod>]
     member _.VisibleRangeClampsAtLegacyMapEdges () =
         let x0, y0, x1, y1 = MapGen.visibleTileRange 64 48 0 0 2048 1536