@mjackson/headers/src/lib/super-headers.test.ts

A toolkit for working with HTTP headers in JavaScript

import * as assert from 'node:assert/strict';
import { describe, it } from 'node:test';

import { Accept } from './accept.ts';
import { AcceptEncoding } from './accept-encoding.ts';
import { AcceptLanguage } from './accept-language.ts';
import { CacheControl } from './cache-control.ts';
import { ContentDisposition } from './content-disposition.ts';
import { ContentType } from './content-type.ts';
import { Cookie } from './cookie.ts';
import { SuperHeaders } from './super-headers.ts';
import { IfNoneMatch } from './if-none-match.ts';

describe('SuperHeaders', () => {
  it('is an instance of Headers', () => {
    let headers = new SuperHeaders();
    assert.ok(headers instanceof SuperHeaders);
    assert.ok(headers instanceof Headers);
  });

  it('initializes with no arguments', () => {
    let headers = new SuperHeaders();
    assert.equal(headers.get('Content-Type'), null);
  });

  it('initializes from an object of header name/value pairs', () => {
    let headers = new SuperHeaders({ 'Content-Type': 'text/plain' });
    assert.equal(headers.get('Content-Type'), 'text/plain');
  });

  it('initializes from an array of key-value pairs', () => {
    let headers = new SuperHeaders([
      ['Content-Type', 'text/plain'],
      ['X-Custom', 'value'],
    ]);
    assert.equal(headers.get('Content-Type'), 'text/plain');
    assert.equal(headers.get('X-Custom'), 'value');
  });

  it('initializes from a Headers instance', () => {
    let h1 = new Headers({ 'Content-Type': 'text/plain' });
    let h2 = new SuperHeaders(h1);
    assert.equal(h2.get('Content-Type'), 'text/plain');
  });

  it('initializes from another SuperHeaders instance', () => {
    let h1 = new SuperHeaders({ 'Content-Type': 'text/plain' });
    let h2 = new SuperHeaders(h1);
    assert.equal(h2.get('Content-Type'), 'text/plain');
  });

  it('initializes from a string', () => {
    let headers = new SuperHeaders('Content-Type: text/plain\r\nContent-Length: 42');
    assert.equal(headers.get('Content-Type'), 'text/plain');
    assert.equal(headers.get('Content-Length'), '42');
  });

  it('appends values', () => {
    let headers = new SuperHeaders();
    headers.append('X-Custom', 'value1');
    headers.append('X-Custom', 'value2');
    assert.equal(headers.get('X-Custom'), 'value1, value2');
  });

  it('sets values', () => {
    let headers = new SuperHeaders();
    headers.set('X-Custom', 'value1');
    headers.set('X-Custom', 'value2');
    assert.equal(headers.get('X-Custom'), 'value2');
  });

  it('deletes values', () => {
    let headers = new SuperHeaders({ 'X-Custom': 'value' });
    headers.delete('X-Custom');
    assert.equal(headers.has('X-Custom'), false);
  });

  it('checks if a header exists', () => {
    let headers = new SuperHeaders({ 'X-Custom': 'value' });
    assert.equal(headers.has('X-Custom'), true);
    assert.equal(headers.has('Content-Type'), false);

    // Accessing this property should not change the result of has()
    let _ = headers.contentType;
    assert.equal(headers.has('Content-Type'), false);
  });

  it('iterates over entries', () => {
    let headers = new SuperHeaders({
      'Content-Type': 'text/plain',
      'Content-Length': '42',
    });
    let entries = Array.from(headers.entries());
    assert.deepEqual(entries, [
      ['content-type', 'text/plain'],
      ['content-length', '42'],
    ]);
  });

  it('iterates over keys', () => {
    let headers = new SuperHeaders({
      'Content-Type': 'text/plain',
      'Content-Length': '42',
    });
    let keys = Array.from(headers.keys());
    assert.deepEqual(keys, ['content-type', 'content-length']);
  });

  it('iterates over set-cookie keys correctly', () => {
    let headers = new SuperHeaders();
    headers.append('Set-Cookie', 'session=abc');
    headers.append('Set-Cookie', 'theme=dark');
    let keys = Array.from(headers.keys());
    assert.deepEqual(keys, ['set-cookie', 'set-cookie']);
  });

  it('iterates over values', () => {
    let headers = new SuperHeaders({
      'Content-Type': 'text/plain',
      'Content-Length': '42',
    });
    let values = Array.from(headers.values());
    assert.deepEqual(values, ['text/plain', '42']);
  });

  it('uses forEach correctly', () => {
    let headers = new SuperHeaders({
      'Content-Type': 'text/plain',
      'Content-Length': '42',
    });
    let result: [string, string][] = [];
    headers.forEach((value, key) => {
      result.push([key, value]);
    });
    assert.deepEqual(result, [
      ['content-type', 'text/plain'],
      ['content-length', '42'],
    ]);
  });

  it('is directly iterable', () => {
    let headers = new SuperHeaders({
      'Content-Type': 'text/plain',
      'Content-Length': '42',
    });
    let entries = Array.from(headers);
    assert.deepEqual(entries, [
      ['content-type', 'text/plain'],
      ['content-length', '42'],
    ]);
  });

  it('omits empty values when stringified', () => {
    let headers = new SuperHeaders();

    // This should appear in the string since it has a media type, it's complete
    headers.contentType = 'text/plain';

    // This should not appear in the string since it's incomplete, missing the type
    headers.contentDisposition.filename = 'example.txt';

    assert.equal(headers.toString(), 'Content-Type: text/plain');
  });

  describe('constructor property init', () => {
    it('handles the accept property', () => {
      let headers = new SuperHeaders({ accept: { 'text/html': 1, 'application/json': 0.9 } });
      assert.equal(headers.get('Accept'), 'text/html,application/json;q=0.9');
    });

    it('handles the acceptEncoding property', () => {
      let headers = new SuperHeaders({ acceptEncoding: { gzip: 1, deflate: 0.8 } });
      assert.equal(headers.get('Accept-Encoding'), 'gzip,deflate;q=0.8');
    });

    it('handles the acceptLanguage property', () => {
      let headers = new SuperHeaders({ acceptLanguage: { 'en-US': 1, en: 0.9 } });
      assert.equal(headers.get('Accept-Language'), 'en-us,en;q=0.9');
    });

    it('handles the acceptRanges property', () => {
      let headers = new SuperHeaders({ acceptRanges: 'bytes' });
      assert.equal(headers.get('Accept-Ranges'), 'bytes');
    });

    it('handles the age property', () => {
      let headers = new SuperHeaders({ age: 42 });
      assert.equal(headers.get('Age'), '42');
    });

    it('handles the cacheControl property', () => {
      let headers = new SuperHeaders({ cacheControl: { public: true, maxAge: 3600 } });
      assert.equal(headers.get('Cache-Control'), 'public, max-age=3600');
    });

    it('handles the connection property', () => {
      let headers = new SuperHeaders({ connection: 'close' });
      assert.equal(headers.get('Connection'), 'close');
    });

    it('handles the contentDisposition property', () => {
      let headers = new SuperHeaders({
        contentDisposition: { type: 'attachment', filename: 'example.txt' },
      });
      assert.equal(headers.get('Content-Disposition'), 'attachment; filename=example.txt');
    });

    it('handles the contentEncoding property', () => {
      let headers = new SuperHeaders({ contentEncoding: 'gzip' });
      assert.equal(headers.get('Content-Encoding'), 'gzip');
    });

    it('handles the contentLanguage property', () => {
      let headers = new SuperHeaders({ contentLanguage: 'en-US' });
      assert.equal(headers.get('Content-Language'), 'en-US');
    });

    it('handles the contentLength property', () => {
      let headers = new SuperHeaders({ contentLength: 42 });
      assert.equal(headers.get('Content-Length'), '42');
    });

    it('handles the contentType property', () => {
      let headers = new SuperHeaders({
        contentType: { mediaType: 'text/plain', charset: 'utf-8' },
      });
      assert.equal(headers.get('Content-Type'), 'text/plain; charset=utf-8');
    });

    it('handles the cookie property', () => {
      let headers = new SuperHeaders({ cookie: [['name', 'value']] });
      assert.equal(headers.get('Cookie'), 'name=value');
    });

    it('handles the date property', () => {
      let headers = new SuperHeaders({ date: new Date('2021-01-01T00:00:00Z') });
      assert.equal(headers.get('Date'), 'Fri, 01 Jan 2021 00:00:00 GMT');
    });

    it('handles the etag property', () => {
      let headers = new SuperHeaders({ etag: '"67ab43"' });
      assert.equal(headers.get('ETag'), '"67ab43"');

      let headers2 = new SuperHeaders({ etag: '67ab43' });
      assert.equal(headers2.get('ETag'), '"67ab43"');

      let headers3 = new SuperHeaders({ etag: 'W/"67ab43"' });
      assert.equal(headers3.get('ETag'), 'W/"67ab43"');
    });

    it('handles the expires property', () => {
      let headers = new SuperHeaders({ expires: new Date('2021-01-01T00:00:00Z') });
      assert.equal(headers.get('Expires'), 'Fri, 01 Jan 2021 00:00:00 GMT');
    });

    it('handles the host property', () => {
      let headers = new SuperHeaders({ host: 'example.com' });
      assert.equal(headers.get('Host'), 'example.com');
    });

    it('handles the ifModifiedSince property', () => {
      let headers = new SuperHeaders({ ifModifiedSince: new Date('2021-01-01T00:00:00Z') });
      assert.equal(headers.get('If-Modified-Since'), 'Fri, 01 Jan 2021 00:00:00 GMT');
    });

    it('handles the ifNoneMatch property', () => {
      let headers = new SuperHeaders({ ifNoneMatch: ['67ab43', '54ed21'] });
      assert.equal(headers.get('If-None-Match'), '"67ab43", "54ed21"');
    });

    it('handles the ifUnmodifiedSince property', () => {
      let headers = new SuperHeaders({ ifUnmodifiedSince: new Date('2021-01-01T00:00:00Z') });
      assert.equal(headers.get('If-Unmodified-Since'), 'Fri, 01 Jan 2021 00:00:00 GMT');
    });

    it('handles the lastModified property', () => {
      let headers = new SuperHeaders({ lastModified: new Date('2021-01-01T00:00:00Z') });
      assert.equal(headers.get('Last-Modified'), 'Fri, 01 Jan 2021 00:00:00 GMT');
    });

    it('handles the location property', () => {
      let headers = new SuperHeaders({ location: 'https://example.com' });
      assert.equal(headers.get('Location'), 'https://example.com');
    });

    it('handles the referer property', () => {
      let headers = new SuperHeaders({ referer: 'https://example.com' });
      assert.equal(headers.get('Referer'), 'https://example.com');
    });

    it('handles the setCookie property', () => {
      let headers = new SuperHeaders({
        setCookie: [
          { name: 'session', value: 'abc', path: '/' },
          { name: 'theme', value: 'dark', expires: new Date('2021-12-31T23:59:59Z') },
        ],
      });
      assert.deepEqual(headers.getSetCookie(), [
        'session=abc; Path=/',
        'theme=dark; Expires=Fri, 31 Dec 2021 23:59:59 GMT',
      ]);
    });

    it('stringifies unknown properties with non-string values', () => {
      let headers = new SuperHeaders({ unknown: 42 });
      assert.equal(headers.get('Unknown'), '42');
    });
  });

  describe('property getters and setters', () => {
    it('supports the accept property', () => {
      let headers = new SuperHeaders();

      assert.ok(headers.accept instanceof Accept);

      headers.accept = 'text/html,application/json;q=0.9';
      assert.deepEqual(headers.accept.size, 2);
      assert.deepEqual(headers.accept.mediaTypes, ['text/html', 'application/json']);
      assert.deepEqual(headers.accept.weights, [1, 0.9]);

      headers.accept = { 'application/json': 0.8, 'text/html': 1 };
      assert.deepEqual(headers.accept.size, 2);
      assert.deepEqual(headers.accept.mediaTypes, ['text/html', 'application/json']);
      assert.deepEqual(headers.accept.weights, [1, 0.8]);

      headers.accept = null;
      assert.ok(headers.accept instanceof Accept);
      assert.equal(headers.accept.toString(), '');
    });

    it('supports the acceptEncoding property', () => {
      let headers = new SuperHeaders();

      assert.ok(headers.acceptEncoding instanceof AcceptEncoding);

      headers.acceptEncoding = 'gzip, deflate';
      assert.deepEqual(headers.acceptEncoding.size, 2);
      assert.deepEqual(headers.acceptEncoding.encodings, ['gzip', 'deflate']);
      assert.deepEqual(headers.acceptEncoding.weights, [1, 1]);

      headers.acceptEncoding = { gzip: 1, deflate: 0.8 };
      assert.deepEqual(headers.acceptEncoding.size, 2);
      assert.deepEqual(headers.acceptEncoding.encodings, ['gzip', 'deflate']);
      assert.deepEqual(headers.acceptEncoding.weights, [1, 0.8]);

      headers.acceptEncoding = null;
      assert.ok(headers.acceptEncoding instanceof AcceptEncoding);
      assert.equal(headers.acceptEncoding.toString(), '');
    });

    it('supports the acceptLanguage property', () => {
      let headers = new SuperHeaders();

      assert.ok(headers.acceptLanguage instanceof AcceptLanguage);

      headers.acceptLanguage = 'en-US,en;q=0.9';
      assert.deepEqual(headers.acceptLanguage.size, 2);
      assert.deepEqual(headers.acceptLanguage.languages, ['en-us', 'en']);
      assert.deepEqual(headers.acceptLanguage.weights, [1, 0.9]);

      headers.acceptLanguage = { en: 1, 'en-US': 0.8 };
      assert.deepEqual(headers.acceptLanguage.size, 2);
      assert.deepEqual(headers.acceptLanguage.languages, ['en', 'en-us']);
      assert.deepEqual(headers.acceptLanguage.weights, [1, 0.8]);

      headers.acceptLanguage = null;
      assert.ok(headers.acceptLanguage instanceof AcceptLanguage);
      assert.equal(headers.acceptLanguage.toString(), '');
    });

    it('supports the acceptRanges property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.acceptRanges, null);

      headers.acceptRanges = 'bytes';
      assert.equal(headers.acceptRanges, 'bytes');

      headers.acceptRanges = null;
      assert.equal(headers.acceptRanges, null);
    });

    it('supports the age property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.age, null);

      headers.age = '42';
      assert.equal(headers.age, 42);

      headers.age = 42;
      assert.equal(headers.age, 42);

      headers.age = null;
      assert.equal(headers.age, null);
    });

    it('supports the cacheControl property', () => {
      let headers = new SuperHeaders();

      assert.ok(headers.cacheControl instanceof CacheControl);

      headers.cacheControl = 'public, max-age=3600';
      assert.equal(headers.cacheControl.public, true);
      assert.equal(headers.cacheControl.maxAge, 3600);

      headers.cacheControl.maxAge = 1800;
      assert.equal(headers.cacheControl.maxAge, 1800);

      headers.cacheControl = { noCache: true, noStore: true };
      assert.equal(headers.cacheControl.noCache, true);
      assert.equal(headers.cacheControl.noStore, true);

      headers.cacheControl = null;
      assert.ok(headers.cacheControl instanceof CacheControl);
      assert.equal(headers.cacheControl.toString(), '');
    });

    it('supports the connection property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.connection, null);

      headers.connection = 'close';
      assert.equal(headers.connection, 'close');

      headers.connection = null;
      assert.equal(headers.connection, null);
    });

    it('supports the contentDisposition property', () => {
      let headers = new SuperHeaders();

      assert.ok(headers.contentDisposition instanceof ContentDisposition);

      headers.contentDisposition = 'attachment; filename="example.txt"';
      assert.equal(headers.contentDisposition.type, 'attachment');
      assert.equal(headers.contentDisposition.filename, 'example.txt');

      headers.contentDisposition.filename = 'new.txt';
      assert.equal(headers.contentDisposition.filename, 'new.txt');

      headers.contentDisposition = { type: 'inline', filename: 'index.html' };
      assert.equal(headers.contentDisposition.type, 'inline');
      assert.equal(headers.contentDisposition.filename, 'index.html');

      headers.contentDisposition = null;
      assert.ok(headers.contentDisposition instanceof ContentDisposition);
      assert.equal(headers.contentDisposition.toString(), '');
    });

    it('supports the contentEncoding property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.contentEncoding, null);

      headers.contentEncoding = 'gzip';
      assert.equal(headers.contentEncoding, 'gzip');

      headers.contentEncoding = ['deflate', 'gzip'];
      assert.equal(headers.contentEncoding, 'deflate, gzip');

      headers.contentEncoding = null;
      assert.equal(headers.contentEncoding, null);
    });

    it('supports the contentLanguage property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.contentLanguage, null);

      headers.contentLanguage = 'en-US';
      assert.equal(headers.contentLanguage, 'en-US');

      headers.contentLanguage = ['en', 'fr'];
      assert.equal(headers.contentLanguage, 'en, fr');

      headers.contentLanguage = null;
      assert.equal(headers.contentLanguage, null);
    });

    it('supports the contentLength property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.contentLength, null);

      headers.contentLength = '42';
      assert.equal(headers.contentLength, 42);

      headers.contentLength = 42;
      assert.equal(headers.contentLength, 42);

      headers.contentLength = null;
      assert.equal(headers.contentLength, null);
    });

    it('supports the contentType property', () => {
      let headers = new SuperHeaders();

      assert.ok(headers.contentType instanceof ContentType);

      headers.contentType = 'text/plain; charset=utf-8';
      assert.equal(headers.contentType.mediaType, 'text/plain');
      assert.equal(headers.contentType.charset, 'utf-8');

      headers.contentType.charset = 'iso-8859-1';
      assert.equal(headers.contentType.charset, 'iso-8859-1');

      headers.contentType = { mediaType: 'text/html' };
      assert.equal(headers.contentType.mediaType, 'text/html');

      headers.contentType = null;
      assert.ok(headers.contentType instanceof ContentType);
      assert.equal(headers.contentType.toString(), '');
    });

    it('supports the cookie property', () => {
      let headers = new SuperHeaders();

      assert.ok(headers.cookie instanceof Cookie);

      headers.cookie = 'name1=value1; name2=value2';
      assert.equal(headers.cookie.get('name1'), 'value1');
      assert.equal(headers.cookie.get('name2'), 'value2');

      headers.cookie.set('name3', 'value3');
      assert.equal(headers.cookie.get('name3'), 'value3');

      headers.cookie = [['name4', 'value4']];
      assert.equal(headers.cookie.get('name4'), 'value4');

      headers.cookie = null;
      assert.ok(headers.cookie instanceof Cookie);
      assert.equal(headers.cookie.toString(), '');
    });

    it('supports the date property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.date, null);

      headers.date = new Date('2021-01-01T00:00:00Z');
      assert.ok(headers.date instanceof Date);
      assert.equal(headers.date.toUTCString(), 'Fri, 01 Jan 2021 00:00:00 GMT');

      headers.date = null;
      assert.equal(headers.date, null);
    });

    it('supports the etag property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.etag, null);

      headers.etag = '"67ab43"';
      assert.equal(headers.etag, '"67ab43"');

      headers.etag = '67ab43';
      assert.equal(headers.etag, '"67ab43"');

      headers.etag = 'W/"67ab43"';
      assert.equal(headers.etag, 'W/"67ab43"');

      headers.etag = '';
      assert.equal(headers.etag, '""');

      headers.etag = '""';
      assert.equal(headers.etag, '""');

      headers.etag = null;
      assert.equal(headers.etag, null);
    });

    it('supports the expires property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.expires, null);

      headers.expires = new Date('2021-01-01T00:00:00Z');
      assert.ok(headers.expires instanceof Date);
      assert.equal(headers.expires.toUTCString(), 'Fri, 01 Jan 2021 00:00:00 GMT');

      headers.expires = null;
      assert.equal(headers.expires, null);
    });

    it('supports the host property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.host, null);

      headers.host = 'example.com';
      assert.equal(headers.host, 'example.com');

      headers.host = null;
      assert.equal(headers.host, null);
    });

    it('supports the ifModifiedSince property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.ifModifiedSince, null);

      headers.ifModifiedSince = new Date('2021-01-01T00:00:00Z');
      assert.ok(headers.ifModifiedSince instanceof Date);
      assert.equal(headers.ifModifiedSince.toUTCString(), 'Fri, 01 Jan 2021 00:00:00 GMT');

      headers.ifModifiedSince = null;
      assert.equal(headers.ifModifiedSince, null);
    });

    it('supports the ifNoneMatch property', () => {
      let headers = new SuperHeaders();

      assert.ok(headers.ifNoneMatch instanceof IfNoneMatch);

      headers.ifNoneMatch = '"67ab43", "54ed21"';
      assert.deepEqual(headers.ifNoneMatch.tags, ['"67ab43"', '"54ed21"']);

      headers.ifNoneMatch = ['67ab43', '54ed21'];
      assert.deepEqual(headers.ifNoneMatch.tags, ['"67ab43"', '"54ed21"']);

      headers.ifNoneMatch = { tags: ['67ab43', '54ed21'] };
      assert.deepEqual(headers.ifNoneMatch.tags, ['"67ab43"', '"54ed21"']);

      headers.ifNoneMatch = null;
      assert.ok(headers.ifNoneMatch instanceof IfNoneMatch);
      assert.equal(headers.ifNoneMatch.toString(), '');
    });

    it('supports the ifUnmodifiedSince property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.ifUnmodifiedSince, null);

      headers.ifUnmodifiedSince = new Date('2021-01-01T00:00:00Z');
      assert.ok(headers.ifUnmodifiedSince instanceof Date);
      assert.equal(headers.ifUnmodifiedSince.toUTCString(), 'Fri, 01 Jan 2021 00:00:00 GMT');

      headers.ifUnmodifiedSince = null;
      assert.equal(headers.ifUnmodifiedSince, null);
    });

    it('supports the lastModified property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.lastModified, null);

      headers.lastModified = new Date('2021-01-01T00:00:00Z');
      assert.ok(headers.lastModified instanceof Date);
      assert.equal(headers.lastModified.toUTCString(), 'Fri, 01 Jan 2021 00:00:00 GMT');

      headers.lastModified = null;
      assert.equal(headers.lastModified, null);
    });

    it('supports the location property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.location, null);

      headers.location = 'https://example.com';
      assert.equal(headers.location, 'https://example.com');

      headers.location = null;
      assert.equal(headers.location, null);
    });

    it('supports the referer property', () => {
      let headers = new SuperHeaders();

      assert.equal(headers.referer, null);

      headers.referer = 'https://example.com';
      assert.equal(headers.referer, 'https://example.com');

      headers.referer = null;
      assert.equal(headers.referer, null);
    });

    it('supports the setCookie property', () => {
      let headers = new SuperHeaders();

      assert.deepEqual(headers.setCookie, []);

      headers.setCookie = 'session=abc';
      assert.equal(headers.setCookie.length, 1);
      assert.equal(headers.setCookie[0].name, 'session');
      assert.equal(headers.setCookie[0].value, 'abc');

      headers.setCookie = { name: 'session', value: 'def' };
      assert.equal(headers.setCookie.length, 1);
      assert.equal(headers.setCookie[0].name, 'session');
      assert.equal(headers.setCookie[0].value, 'def');

      headers.setCookie = ['session=abc', 'theme=dark'];
      assert.equal(headers.setCookie.length, 2);
      assert.equal(headers.setCookie[0].name, 'session');
      assert.equal(headers.setCookie[0].value, 'abc');
      assert.equal(headers.setCookie[1].name, 'theme');
      assert.equal(headers.setCookie[1].value, 'dark');

      // Can use ...spread to add new cookies
      headers.setCookie = [...headers.setCookie, 'lang=en'];
      assert.equal(headers.setCookie.length, 3);
      assert.equal(headers.setCookie[2].name, 'lang');
      assert.equal(headers.setCookie[2].value, 'en');

      headers.setCookie = [
        { name: 'session', value: 'def' },
        { name: 'theme', value: 'light' },
      ];
      assert.equal(headers.setCookie.length, 2);
      assert.equal(headers.setCookie[0].name, 'session');
      assert.equal(headers.setCookie[0].value, 'def');
      assert.equal(headers.setCookie[1].name, 'theme');
      assert.equal(headers.setCookie[1].value, 'light');

      // Can use push() to add new cookies
      headers.setCookie.push({ name: 'lang', value: 'fr' });
      assert.equal(headers.setCookie.length, 3);
      assert.equal(headers.setCookie[2].name, 'lang');
      assert.equal(headers.setCookie[2].value, 'fr');

      headers.setCookie = null;
      assert.deepEqual(headers.setCookie, []);
    });
  });
});