portfolio/src/shared/lib/cn.test.ts

import { cn } from './cn';

describe('cn', () => {
  describe('basic merging', () => {
    it('returns single class unchanged', () => {
      expect(cn('foo')).toBe('foo');
    });

    it('joins multiple classes', () => {
      expect(cn('foo', 'bar')).toBe('foo bar');
    });
  });

  describe('conditional classes', () => {
    it('includes truthy conditional', () => {
      expect(cn('foo', true && 'bar')).toBe('foo bar');
    });

    it('excludes falsy conditional', () => {
      expect(cn('foo', false && 'bar')).toBe('foo');
    });
  });

  describe('object syntax', () => {
    it('includes classes with truthy object values', () => {
      expect(cn({ foo: true, bar: false })).toBe('foo');
    });
  });

  describe('tailwind conflict resolution', () => {
    it('last padding wins', () => {
      expect(cn('px-2', 'px-4')).toBe('px-4');
    });

    it('last text color wins', () => {
      expect(cn('text-red-500', 'text-blue-500')).toBe('text-blue-500');
    });
  });
});