bun.sh/test/js/node/test/parallel/test-http2-single-headers.js

'use strict';

const common = require('../common');
if (!common.hasCrypto)
  common.skip('missing crypto');
const assert = require('assert');
const http2 = require('http2');
const { once } = require('events');
const server = http2.createServer();

// Each of these headers must appear only once
const singles = [
  'content-type',
  'user-agent',
  'referer',
  'authorization',
  'proxy-authorization',
  'if-modified-since',
  'if-unmodified-since',
  'from',
  'location',
  'max-forwards',
];

server.on('stream', common.mustNotCall());

server.listen(0, "127.0.0.1", common.mustCall(async () => {
  const client = http2.connect(`http://127.0.0.1:${server.address().port}`);
  await once(client, 'connect');
  for (const i of singles) {
 
    assert.throws(
      () => client.request({ [i]: 'abc', [i.toUpperCase()]: 'xyz' }),
      {
        code: 'ERR_HTTP2_HEADER_SINGLE_VALUE',
        name: 'TypeError',
        message: `Header field "${i}" must only have a single value`
      }
    );

    assert.throws(
      () => client.request({ [i]: ['abc', 'xyz'] }),
      {
        code: 'ERR_HTTP2_HEADER_SINGLE_VALUE',
        name: 'TypeError',
        message: `Header field "${i}" must only have a single value`
      }
    );
  }

  server.close();
  client.close();
}));