beforeEach hook in Mocha test causing timeout

Not sure exactly what's happened to my tests, but all of the sudden, I'm getting a timeout from my beforeEach whenever I try to do any sort of Mongoose operation.

var Notification = require('../lib/models').model('Notification');

describe('API Tests', function() {
    beforeEach(function(done){
        Notification.collection.remove(done);
    });

    // remainder of tests
});

If I write a test such as:

describe('When performing Mongoose operations', function() {
    it('should open a connection' , function(done) {
        mongoose.connect(mongooseUri, options);
        var conn = mongoose.connection;

        conn.on('error', console.error.bind(console, 'connection error'));
        conn.once('open', function(callback) {
            console.log('connection to MongoDB opened');
        });

        done();
    }
)};

It will pass. My credentials are correct, and other tests that perform Mongoose operations are working as expected, just not in the beforeEach hook. What am I doing wrong?