diff --git a/packages/ui/src/test/setup.ts b/packages/ui/src/test/setup.ts
index 4134f95..7b7ab90 100644
--- a/packages/ui/src/test/setup.ts
+++ b/packages/ui/src/test/setup.ts
@@ -7,61 +7,65 @@ import { matchesMediaQuery, resetAccessibilityPreferences } from "./a11y";
 
 afterEach(() => {
   resetAccessibilityPreferences();
-  cleanup();
-});
-
-class ResizeObserverMock {
-  observe() {}
-  unobserve() {}
-  disconnect() {}
-}
-
-class PointerEventMock extends MouseEvent {
-  constructor(type: string, props: PointerEventInit = {}) {
-    super(type, props);
+  if (typeof document !== "undefined") {
+    cleanup();
   }
+});
+
+if (typeof window !== "undefined" && typeof MouseEvent !== "undefined") {
+  class ResizeObserverMock {
+    observe() {}
+    unobserve() {}
+    disconnect() {}
+  }
+
+  class PointerEventMock extends MouseEvent {
+    constructor(type: string, props: PointerEventInit = {}) {
+      super(type, props);
+    }
+  }
+
+  Object.defineProperty(window, "matchMedia", {
+    writable: true,
+    value: vi.fn().mockImplementation((query: string) => ({
+      matches: matchesMediaQuery(query),
+      media: query,
+      onchange: null,
+      addEventListener: vi.fn(),
+      removeEventListener: vi.fn(),
+      addListener: vi.fn(),
+      removeListener: vi.fn(),
+      dispatchEvent: vi.fn()
+    }))
+  });
+
+  Object.defineProperty(window, "ResizeObserver", {
+    writable: true,
+    value: ResizeObserverMock
+  });
+
+  Object.defineProperty(window, "PointerEvent", {
+    writable: true,
+    value: PointerEventMock
+  });
+
+  Object.defineProperty(window.HTMLElement.prototype, "scrollIntoView", {
+    configurable: true,
+    value: vi.fn()
+  });
+
+  Object.defineProperty(window.HTMLElement.prototype, "hasPointerCapture", {
+    configurable: true,
+    value: vi.fn(() => false)
+  });
+
+  Object.defineProperty(window.HTMLElement.prototype, "releasePointerCapture", {
+    configurable: true,
+    value: vi.fn()
+  });
+
+  Object.defineProperty(window.HTMLElement.prototype, "setPointerCapture", {
+    configurable: true,
+    value: vi.fn()
+  });
 }
-
-Object.defineProperty(window, "matchMedia", {
-  writable: true,
-  value: vi.fn().mockImplementation((query: string) => ({
-    matches: matchesMediaQuery(query),
-    media: query,
-    onchange: null,
-    addEventListener: vi.fn(),
-    removeEventListener: vi.fn(),
-    addListener: vi.fn(),
-    removeListener: vi.fn(),
-    dispatchEvent: vi.fn()
-  }))
-});
-
-Object.defineProperty(window, "ResizeObserver", {
-  writable: true,
-  value: ResizeObserverMock
-});
-
-Object.defineProperty(window, "PointerEvent", {
-  writable: true,
-  value: PointerEventMock
-});
-
-Object.defineProperty(window.HTMLElement.prototype, "scrollIntoView", {
-  configurable: true,
-  value: vi.fn()
-});
-
-Object.defineProperty(window.HTMLElement.prototype, "hasPointerCapture", {
-  configurable: true,
-  value: vi.fn(() => false)
-});
-
-Object.defineProperty(window.HTMLElement.prototype, "releasePointerCapture", {
-  configurable: true,
-  value: vi.fn()
-});
-
-Object.defineProperty(window.HTMLElement.prototype, "setPointerCapture", {
-  configurable: true,
-  value: vi.fn()
-});
diff --git a/vitest.config.ts b/vitest.config.ts
index 23b8a94..dafc40e 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -49,7 +49,7 @@ export default defineConfig({
   test: {
     clearMocks: true,
     environment: "jsdom",
-    include: ["packages/ui/src/**/*.test.{ts,tsx}"],
+    include: ["packages/ui/src/**/*.test.{ts,tsx}", "scripts/harness/**/*.test.ts"],
     restoreMocks: true,
     setupFiles: [path.resolve(rootDir, "packages/ui/src/test/setup.ts")]
   }