badcode#31

var f = function fun (x, f)
{   var newf="",newn="",result="",aux=[],i=0;
    for(;i<f.length;++i)
    {aux.push(f[i]);}
    f=aux;aux=[];
    for(i=0;i<x.length;++i)
    {aux.push(x[i]);}
    x=aux;
    if(f.indexOf('#')== -1) return f;
    for(i=0;i<f.indexOf('#');i=i+1)
    {result=result+f[i];}
    result=result+x[0];
    for(i=i+1;i<f.length;i=i+1)
    {newf=newf+f[i];}
    for(i=1;i<x.length;i=i+1)
    {newn=newn+x[i];}
    return result+fun(newn,newf);}


function test (implementation, testcases) {
    for ( const {input, output} of testcases ) {
        const result = implementation(...input);
        if (result === output) {
            console.log("-> SUCCESS");
        } else {
            console.log(`-> FAILURE : expected ${JSON.stringify(output)} but got ${JSON.stringify(result)}`);
        }
    }
}

const testcases = [
    {
        input: ['1234567890', '(###) ###-####'],
        output: '(123) 456-7890',
    },
    {
        input: ['07123456789', '##### ######'],
        output: '07123 456789',
    },
    {
        input: ['01189998819991197253', '#### ### ### ### ### ### #'],
        output: '0118 999 881 999 119 725 3',
    },
];

test(f, testcases);