30. Simulating Backends with Network Interception

Mocking with page.route()

test("simulate 500 server error toast", async ({ page }) => {
  await page.route("**/api/checkout", (route) => {
    route.fulfill({
      status: 500,
      contentType: "application/json",
      body: JSON.stringify({ error: "Payment server timeout" })
    });
  });
await page.goto("/checkout");
  await page.getByRole("button", { name: "Pay Now" }).click();
  await expect(page.getByRole("alert")).toHaveText("Payment server timeout");
});