Mocha: get stacktrace when running mocha programmatically

Question

I am running tests using mocha programmatically and able to run the tests, get full title using following code but I couldn't find any way to get complete stack trace that is being printed on the commandline. How do I get the complete stack trace using mocha as library.

mocha.run(function(failures){
    if (failures) {
        console.log('it failed');
    } else {
        console.log('it passed');
    }
    process.on('exit', function () {
        process.exit(failures);
    });
}).on('fail', function(test){
    title =  test.fullTitle();
}).on('pass', function(test){
    title =  test.fullTitle();
});

Answer 1

I am able to get stacktrace with

var stackTrace = test.err.stack;