Minimal interface covering the Bun-specific HTTP operations used by this adapter. Inject this interface to test the adapter without real Bun.
serve(options: { port: number; hostname?: string; fetch: () => Response | undefined | Promise<Response | undefined>; websocket?: BunWebSocketHandlers; }): BunServer
Starts an HTTP server.
The fetch callback receives the BunServer as its second argument
(Bun's own signature) because server.upgrade() is the only way to
perform a WebSocket handshake, and it may resolve undefined to tell Bun
that the request was upgraded and needs no response.