test(jsdom): resettable scrollIntoView spy + dedupe matchMedia stub

tests/accessible-table.dom.test.tsx

@@ -1,30 +1,14 @@
 import { render, screen } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
-import { describe, expect, it, vi } from "vitest";
+import { describe, expect, it } from "vitest";
 import { AccessibleTable } from "@/components/AccessibleTable";
+import { installMatchMediaStub as setMatchMedia } from "./setup/jsdom.setup";
 
 // Interactive counterpart to tests/accessible-table-fallback.test.ts (which asserts
 // on the SSR-rendered HTML string). This exercises the same component under jsdom
 // via @testing-library/react so real DOM state + user interaction are covered: the
 // mobile "Expand table" affordance and the full-screen dialog it toggles.
 
-function setMatchMedia(matches: boolean) {
-  Object.defineProperty(window, "matchMedia", {
-    writable: true,
-    configurable: true,
-    value: vi.fn().mockImplementation((query: string) => ({
-      matches,
-      media: query,
-      onchange: null,
-      addEventListener: vi.fn(),
-      removeEventListener: vi.fn(),
-      addListener: vi.fn(),
-      removeListener: vi.fn(),
-      dispatchEvent: vi.fn(),
-    })),
-  });
-}
-
 const columns = ["Score", "Management"];
 const rows = [["0", "Monitor observations"]];
 

tests/setup/jsdom.setup.ts

@@ -9,7 +9,7 @@ import "@testing-library/jest-dom/vitest";
 import { cleanup } from "@testing-library/react";
 import { afterEach, beforeEach, vi } from "vitest";
 
-function installMatchMediaStub(matches = false) {
+export function installMatchMediaStub(matches = false) {
   Object.defineProperty(window, "matchMedia", {
     writable: true,
     configurable: true,
@@ -29,9 +29,13 @@ function installMatchMediaStub(matches = false) {
 beforeEach(() => {
   installMatchMediaStub(false);
   // jsdom does not implement scrollIntoView; components call it on focus/expand.
-  if (!Element.prototype.scrollIntoView) {
-    Element.prototype.scrollIntoView = vi.fn();
+  // Ensure a base impl exists, then re-spy each test so the mock's call history is
+  // reset every time — vi.restoreAllMocks() only restores vi.spyOn spies, not a
+  // one-time plain vi.fn() assignment.
+  if (typeof Element.prototype.scrollIntoView !== "function") {
+    Element.prototype.scrollIntoView = () => {};
   }
+  vi.spyOn(Element.prototype, "scrollIntoView").mockImplementation(() => {});
 });
 
 afterEach(() => {