1 files changed, 31 insertions, 1 deletions
diff --git a/src/LivingVillage.Desktop.Tests/AssetPackTests.fs b/src/LivingVillage.Desktop.Tests/AssetPackTests.fs
index fc235d0..46513f9 100644
--- a/src/LivingVillage.Desktop.Tests/AssetPackTests.fs
+++ b/src/LivingVillage.Desktop.Tests/AssetPackTests.fs
@@ -36,11 +36,41 @@ type AssetPackTests () =
         Assert.AreEqual<int>(cc0TileAtlasHeight, height)
         Assert.AreEqual<int>(0, width % Sim.tilePixels)
         Assert.AreEqual<int>(0, height % Sim.tilePixels)
-        Assert.AreEqual<int>(4, width / Sim.tilePixels)
+        Assert.AreEqual<int>(cc0TileCount, width / Sim.tilePixels)
+        Assert.AreEqual<int>(cc0TileAtlasWidth, width)
         Assert.AreEqual<int>(2, Sim.tilePixels / cc0TileSourcePixels)
         Assert.AreEqual<int>(0, Sim.tilePixels % cc0TileSourcePixels)
 
     [<TestMethod>]
+    member _.Cc0StructureTileIndicesFitTheAtlasAndWaterHasTwoPhases () =
+        // Every P34 self-drawn structure cell must sit inside the 12-tile atlas band.
+        let indices =
+            [ cc0TileIndexWaterA
+              cc0TileIndexWaterB
+              cc0TileIndexRoofRidge
+              cc0TileIndexRoofEave
+              cc0TileIndexWallWood
+              cc0TileIndexWallWindow
+              cc0TileIndexRailing
+              cc0TileIndexDoor ]
+        for index in indices do
+            Assert.IsTrue(index >= 0 && index < cc0TileCount, sprintf "cc0 tile index %d out of atlas" index)
+        let width, _ = pngDimensions (assetPath cc0TileAtlasRelativePath)
+        Assert.IsTrue(width >= (List.max indices + 1) * Sim.tilePixels, "atlas must cover every structure index")
+        // Two-phase water: phase depends only on tick/tile, always in {A, B}, and both
+        // phases appear across a row of tiles in one frame.
+        Assert.AreEqual<int>(2, cc0WaterFrameCount)
+        let phases =
+            [ for tileX in 0 .. 15 -> cc0WaterTileIndexAt 0L tileX 0 ]
+            |> Set.ofList
+        Assert.IsTrue((phases = Set.ofList [ cc0TileIndexWaterA; cc0TileIndexWaterB ]),
+                      "one frame must show both water phases across the river")
+        for tileX in 0 .. 15 do
+            for tileY in 0 .. 15 do
+                let index = cc0WaterTileIndexAt 12345L tileX tileY
+                Assert.IsTrue(index = cc0TileIndexWaterA || index = cc0TileIndexWaterB)
+
+    [<TestMethod>]
     member _.Cc0CharacterAtlasIsIntegerMultipleOfTheCellGrid () =
         let width, height = pngDimensions (assetPath cc0CharacterAtlasRelativePath)
         Assert.AreEqual<int>(cc0CharacterAtlasWidth, width)