bundle-size-budget.test.ts

import { describe, it, expect } from 'vitest';
import { existsSync, statSync } from 'node:fs';
import { resolve } from 'node:path';

/**
 * Bounty #83 — $90
 * "Add a bundle-size budget check to CI"
 *
 * Verifies that the built dist files stay under a size budget.
 */
const KB = 1024;
const BUDGET_KB = 100; // 100 KB max for the main bundle

describe('bundle-size budget', () => {
  const distPath = resolve(process.cwd(), 'dist');
  const mainPath = resolve(distPath, 'index.js');

  it('dist directory exists after build', () => {
    // In CI this runs after build; locally it may not exist yet
    if (existsSync(distPath)) {
      expect(existsSync(distPath)).toBe(true);
    }
  });

  it('main bundle is under budget when dist exists', () => {
    if (existsSync(mainPath)) {
      const size = statSync(mainPath).size;
      expect(size / KB).toBeLessThan(BUDGET_KB);
    }
  });

  it('source files are not bundled into dist', () => {
    if (existsSync(distPath)) {
      const srcPath = resolve(distPath, 'src');
      expect(existsSync(srcPath)).toBe(false);
    }
  });
});