Function sendPostRequest

test/server/streamableHttp.test.ts:99–121

* Helper to send JSON-RPC request

(
    baseUrl: URL,
    message: JSONRPCMessage | JSONRPCMessage[],
    sessionId?: string,
    extraHeaders?: Record<string, string>
)

 * Helper to send JSON-RPC request
 */
async function sendPostRequest(
    baseUrl: URL,
    message: JSONRPCMessage | JSONRPCMessage[],
    sessionId?: string,
    extraHeaders?: Record<string, string>
): Promise<Response> {
    const headers: Record<string, string> = {
        'Content-Type': 'application/json',
        Accept: 'application/json, text/event-stream',
        ...extraHeaders
    };

    if (sessionId) {
        headers['mcp-session-id'] = sessionId;
        headers['mcp-protocol-version'] = '2025-11-25';
    }

    return fetch(baseUrl, {
        method: 'POST',
        headers,
        body: JSON.stringify(message)
    });
}

function expectErrorResponse(
    data: unknown,