test(repo): less noisy test output (#11505)

setupTests.ts

@@ -3,6 +3,7 @@ import fs from "fs";
 // vitest.setup.ts
 import "vitest-canvas-mock";
 import "@testing-library/jest-dom";
+import { configure } from "@testing-library/react";
 import { vi } from "vitest";
 
 import polyfill from "./packages/excalidraw/polyfill";
@@ -16,6 +17,21 @@ import {
 Object.assign(globalThis, testPolyfills);
 PolyfillLocalStorage();
 
+// By default testing-library dumps the entire serialized DOM into the error
+// message whenever a `waitFor`/`getBy*` fails, which floods the test output
+// (often hundreds of lines of HTML per failure). Strip it out unless
+// VITE_DEBUG_DOM is enabled (see .env.test), e.g. `VITE_DEBUG_DOM=true yarn test`.
+const debugDom = ["true", "1"].includes(process.env.VITE_DEBUG_DOM ?? "");
+if (!debugDom) {
+  configure({
+    getElementError: (message) => {
+      const error = new Error(message ?? undefined);
+      error.name = "TestingLibraryElementError";
+      return error;
+    },
+  });
+}
+
 vi.mock("@excalidraw/common", async (importOriginal) => {
   const module = await importOriginal<typeof import("@excalidraw/common")>();