test(NetworkBanner): fix undefined renderWithNetwork helper

src/components/NetworkBanner.test.tsx

@@ -1,8 +1,9 @@
 import { render, screen } from "@testing-library/react";
+import type { ReactElement } from "react";
 import { describe, expect, it, vi } from "vitest";
 
 import { useSorokit } from "@/context/useSorokit";
-import type { NetworkInfo } from "@/lib/client";
+import type { NetworkInfo, NetworkName } from "@/lib/client";
 
 import { NetworkBanner } from "./NetworkBanner";
 
@@ -16,6 +17,23 @@
   } as unknown as ReturnType<typeof useSorokit>);
 }
 
+/**
+ * Renders `element` (defaulting to a bare `<NetworkBanner />`) against a
+ * synthetic network built from just its `name` — for tests that only care
+ * about how the banner reacts to an arbitrary/unknown network name, without
+ * spelling out a full `NetworkInfo` fixture (rpcUrl/passphrase/horizonUrl
+ * are irrelevant to `NetworkBanner`, which only ever reads `network.name`).
+ */
+function renderWithNetwork(name: NetworkName, element: ReactElement = <NetworkBanner />) {
+  mockNetwork({
+    name,
+    rpcUrl: "https://example-rpc.test",
+    passphrase: `${name} passphrase`,
+    horizonUrl: "https://example-horizon.test",
+  });
+  return render(element);
+}
+
 const MAINNET_NETWORK: NetworkInfo = {
   name: "mainnet",
   rpcUrl: "https://soroban.stellar.org",