proxypain.js

// Make a bunch of stub objects like this,
// commingling mock behavior with test assertions.
const npm = {
        config: {
            get: function(prop) {
                expect(prop).to.equal('registry');
                if (prop === 'registry') {
                    return npmRegistry;
                }
            }
        }
    },        

    _ = require('lodash'),
    q = require('q'),
    packageExists = proxyquire('../../../lib/core/package-exists', {
        // Mock out everything this module needs. Here's one example:
        '../utils/get-npm': _.constant(q(npm))
        // So much cruft, even for something so simple!
    });