How do I get the code coverage output to display using expresso?

I'm working on getting Expresso set up and some tests running. I followed along with a tutorial on node tuts and have 4 tests running, and passing. Now I'm trying to get a code coverage output to show up when I run the tests, like the docs show. However, I'm sort of lost.

My super basic learning example tests are in a file called test.js in a folder called test:

var Account = require('../lib/account');

require('should');

module.exports = {
    "initial balance should be 0" : function(){
        var account = Account.create();
        account.should.have.property('balance');
        account.balance.should.be.eql(0);
    },

    "crediting account should increase the balance" : function(){
        var account = Account.create();
        account.credit(10);
        account.balance.should.be.eql(10);
    },

    "debiting account should decrease the balance" : function(){
        var account = Account.create();
        account.debit(5);
        account.balance.should.be.eql(-5);
    },

    "transferring from account a to b b should decrease from a and increase b": function(){
        var accountA = Account.create();
        var accountB = Account.create();
        accountA.credit(100);
        accountA.transfer(accountB, 25);
        accountA.balance.should.be.eql(75);
        accountB.balance.should.be.eql(25);
    }
}

And the code itself is in lib/account.js:

var Account = function(){
    this.balance = 0;
}

module.exports.create = function(){
    return new Account();
}

Account.prototype.credit = function(amt){
    this.balance += amt;
}

Account.prototype.debit = function(amt){
    this.balance -= amt;
}

Account.prototype.transfer = function(acct, amt){
    this.debit(amt);
    acct.credit(amt);
}

Account.prototype.empty = function(acct){
    this.debit(this.balance);
}

When I run expresso from the command line, I get:

$ expresso

    100% 4 tests

Likewise, if I run expresso with a -c flag or a variety of other options, I get the same output. I'd like to get the code coverage output shown in the docs. I've also run the command $ node-jscoverage lib lib-cov, and the lib-cov folder has things in it now..

What am I missing?

Best result I've found so far was to edit paths on test run:

This is run_tests.sh

#! /bin/bash

rm -Rf ./app-cov
node_modules/expresso/deps/jscoverage/node-jscoverage app/ app-cov
NODE_PATH=$NODE_PATH:/usr/local/lib/node:/usr/local/lib/node_modules:./mmf_node_modules:./app-cov node_modules/expresso/bin/expresso -c