unit testing async-waterfall using mocha - node.js

Question

I am using Mocha as a testing framework for my node.js application.
I have an existing module that uses async-waterfall node module.I am trying to write a unit test case for it. I am unable to write a test case for the second function in the array. Any tips on how would I pass the result of one function to the next function in the array
var async = require('async');
module.exports.resetPassword = function(req,res,next){
async.waterfall([
function(done){
var token = do something;
done(err,token);
},
function(token,done){
//do some stuff
res.status(200).send('success');
},
]function(err){
//send failure response
});
};

Answer 1

I think I understand the issue now.
In your test - you execute the line:
user.resetPassword(request,response,next);
And immediately after that - the line:
cryptoStub.restore();
The issue is - that async.waterfall will start the first method, but before it runs the second one, it will run the next line from the unit test, and therefore you don`t see the next method. Code that will solve it will be like:
user.resetPassword(request,response,function(err) {
cryptoStub.restore();
done();
});
Does it look better?

Answer 2

My code is as follows. My issue is around writing a unit test case for this method. I am using mocha along with sinon for stubbing. The unit test that I have written is
Unit Test
it("Should return an error if there is an error in retrieving the user details from the db",function(done)
{
request={
body:{
email:'test#test.com'
}
};
var expectedMessageFromCrypto = '12121212121';
var cryptoStub = sinon.stub(crypto, "randomBytes",function(err,callback){
callback(null,expectedMessageFromCrypto);
});
user.resetPassword(request,response,next);
cryptoStub.restore();
done();
});
});
The resetPassword module
methods.exports.resetPassword = function (req, res, next) {
var token = null;
async.waterfall([
function (done) {
crypto.randomBytes(16, function (err, buf) {
if(err){
return res.status(400);
}
else{
token = buf.toString('hex');
}
done(err, token);
});
},
function (token, done) {
var user = getUserInformation(req.body.email);
sendEmail(user, done);
}
], function (err) {
if (err) {
logger.error('error in sending confirmation mail');
return next(err);
}
res.status(200).send('success');
});
};