With the changes above, we can add a case like so:

```javascript
it('encapsulates exceptions in rejections', function (done) {                                                     
    var exception = new TypeError(),
        pe1 = new Promise(),
        pe2;

    pe1.reject('foo');

    pe2 = pe1.mapError(function () {
        throw exception;
    }); 

    pe2.onRejected(function (r) {
        assert.equal('rejected', pe2.state());
        assert.equal(exception, r); 
        done();
    }); 
});
```