test(app): cover Solid virtualizer cache updates

packages/app/package.json

@@ -17,8 +17,9 @@
     "dev": "vite",
     "build": "vite build",
     "serve": "vite preview",
-    "test": "bun run test:unit",
+    "test": "bun run test:unit && bun run test:virtualizer",
     "test:unit": "bun test --only-failures --preload ./happydom.ts ./src",
+    "test:virtualizer": "bun test --conditions=browser --preload ./happydom.ts ./test-browser/solid-virtual.test.ts",
     "test:unit:watch": "bun test --watch --preload ./happydom.ts ./src",
     "test:e2e": "playwright test",
     "test:e2e:local": "playwright test",

packages/app/test-browser/solid-virtual.test.ts

@@ -0,0 +1,27 @@
+import { expect, test } from "bun:test"
+import { createVirtualizer } from "@tanstack/solid-virtual"
+import { createRoot, createSignal } from "solid-js"
+
+test("reactive count updates preserve measured row sizes", () => {
+  createRoot((dispose) => {
+    const [count, setCount] = createSignal(2)
+    const virtualizer = createVirtualizer<HTMLDivElement, HTMLDivElement>({
+      get count() {
+        return count()
+      },
+      getScrollElement: () => null,
+      estimateSize: () => 60,
+      initialRect: { width: 800, height: 600 },
+    })
+
+    expect(virtualizer.getTotalSize()).toBe(120)
+    virtualizer.resizeItem(0, 100)
+    expect(virtualizer.getTotalSize()).toBe(160)
+
+    setCount(3)
+
+    expect(virtualizer.itemSizeCache.get(0)).toBe(100)
+    expect(virtualizer.getTotalSize()).toBe(220)
+    dispose()
+  })
+})