Do you mean having something like this?
```javascript
describe('#prompt', function () {
    beforeEach(function () {
      this.questions = [];
      this.cb = function () {};
      this.spy = sinon.spy(inquirer, 'prompt');
    });
    it('pass its arguments to inquirer', function () {
      this.adapter.prompt(this.questions, this.cb);
      assert(this.spy.withArgs(this.questions, this.cb).calledOnce);
    });

    afterEach(function () {
      inquirer.prompt.restore();
    });
```

For some reason it doesn't  feel right to me...let me know :)