import capitalize from '../capitalize'; describe('capitalize', () => { it('should capitalize the first character of a string', () => { expect(capitalize('antd')).toBe('Antd'); expect(capitalize('Antd')).toBe('Antd'); expect(capitalize(' antd')).toBe(' antd'); expect(capitalize('')).toBe(''); }); it('should return the original value when is not a string', () => { expect(capitalize(1 as any)).toBe(1); expect(capitalize(true as any)).toBe(true); expect(capitalize(undefined as any)).toBe(undefined); expect(capitalize(null as any)).toBe(null); }); });