Jest - Testing Context (this)

I'd like to test if the context (this) of x is the same as the context of y. Given the following example:

var x = {
  hello: function() {
    return this.world;
  }
}

var y = {
  world: 'stackoverflow';
}

x.hello.bind(y)();

I'd expect x.hello to return stackoverflow. Is this achievable? How is this achieved?