import { addHexPrefix } from './addHexPrefix' ; describe ( 'addHexPrefix' , ( ) => { it ( 'adds hex prefix to regular string' , ( ) => { const actual = addHexPrefix ( 'ABCDEF1234' ) ; expect ( actual ) . toBe ( '0xABCDEF1234' ) ; } ) ; it ( 'does nothing when a hex prefix is present in a string' , ( ) => { const actual = addHexPrefix ( '0xABCDEF1234' ) ; expect ( actual ) . toBe ( '0xABCDEF1234' ) ; } ) ; } ) ;