import { expect } from 'chai' ; import { describe , it } from 'mocha' ; import { identityFunc } from '../identityFunc' ; describe ( 'identityFunc' , ( ) => { it ( 'returns the first argument it receives' , ( ) => { expect ( identityFunc ( ) ) . to . equal ( undefined ) ; expect ( identityFunc ( undefined ) ) . to . equal ( undefined ) ; expect ( identityFunc ( null ) ) . to . equal ( null ) ; const obj = { } ; expect ( identityFunc ( obj ) ) . to . equal ( obj ) ; } ) ; } ) ;