Handle race condition in offscreen route change test

Author: markdalgleish

integration/vite-route-exports-modified-offscreen-test.ts

@@ -33,7 +33,7 @@ const files = {
     export const loader = () => "hello";
 
     export default function Route() {
-      const loaderData = useLoaderData() ?? null;
+      const loaderData = useLoaderData();
       return (
         <div data-loader-data>loaderData = {JSON.stringify(loaderData)}</div>
       );
@@ -76,19 +76,24 @@ test.describe(async () => {
       originalContents = contents;
       return contents.replace(/export const loader.*/, "");
     });
+    // Give the server time to pick the manifest change
+    await new Promise((resolve) => setTimeout(resolve, 200));
 
     // After browser reload, client should be aware that there's no loader on the other route
     if (browserName === "webkit") {
       // Force new page instance for webkit.
       // Otherwise browser doesn't seem to fetch new manifest probably due to caching.
       page = await context.newPage();
     }
-    await page.goto(`http://localhost:${port}`, { waitUntil: "networkidle" });
-    await expect(page.locator("[data-mounted]")).toHaveText("Mounted: yes");
-    await page.getByRole("link", { name: "/other" }).click();
-    await expect(page.locator("[data-loader-data]")).toHaveText(
-      "loaderData = null"
-    );
+    // In case the earlier wait wasn't enough, let the test try again
+    await expect(async () => {
+      await page.goto(`http://localhost:${port}`, { waitUntil: "networkidle" });
+      await expect(page.locator("[data-mounted]")).toHaveText("Mounted: yes");
+      await page.getByRole("link", { name: "/other" }).click();
+      await expect(page.locator("[data-loader-data]")).toHaveText(
+        "loaderData = null"
+      );
+    }).toPass();
     expect(pageErrors).toEqual([]);
 
     // Revert route to original state to check HMR works and to ensure the