import { describe, expect, it } from 'vitest';
import type { FastifyRequest } from 'fastify';
import { getRequestId, requestIdHeaders } from './request-context.js';

function makeReq(headers: FastifyRequest['headers'], id = 'generated-id'): FastifyRequest {
  return { headers, id } as FastifyRequest;
}

describe('request id propagation helpers', () => {
  it('prefers inbound x-request-id over generated request id', () => {
    expect(getRequestId(makeReq({ 'x-request-id': 'req-inbound' }))).toBe('req-inbound');
  });

  it('falls back to the Fastify request id', () => {
    expect(getRequestId(makeReq({}))).toBe('generated-id');
  });

  it('builds outbound request-id headers only when a value exists', () => {
    expect(requestIdHeaders('req-123')).toEqual({ 'x-request-id': 'req-123' });
    expect(requestIdHeaders(undefined)).toEqual({});
  });
});