Question: `document.cookie` is like a string, but it is not a string. To quote the example from the [Mozilla doc](https://developer.mozilla.org/En/Document.cookie):

```
document.cookie = "name=oeschger";
document.cookie = "favorite_food=tripe";
alert(document.cookie);
// displays: name=oeschger;favorite_food=tripe

```

If you tried to make a mock cookie using only a string, you would *not* get the same results:

```
var mockCookie = "";
mockCookie = "name=oeschger";
mockCookie = "favorite_food=tripe";
alert(mockCookie);
// displays: favorite_food=tripe

```

So, if you wanted to unit test a module that operates on the cookie, and if you wanted to use a mock cookie for those tests, could you? **How?**

Answer: 
I figured out that jasmine has `spyOnProperty` which can be used for when you want to spy on getter and setters of objects. So I solved my issue with this:

```
const cookie: string = 'my-cookie=cookievalue;';    
spyOnProperty(document, 'cookie', 'get').and.returnValue(cookie);

```
I know this is an old topic, but in my case expiring cookies was necessary so here's a solution that combines the above answers and a `setTimeout` call to expire cookies after `X` seconds:

```
const fakeCookies = {
    // cookie jar
    all: {},

    // timeouts
    timeout: {},

    // get a cookie
    get: function(name)
    {
        return this.all[ name ]
    },

    // set a cookie
    set: function(name, value, expires_seconds)
    {
        this.all[ name ] = value;

        if ( expires_seconds ) {
            ! this.timeout[ name ] || clearTimeout( this.timeout[ name ] )
            this.timeout[ name ] = setTimeout(() => this.unset(name), parseFloat(expires_seconds) * 1000)
        }
    },

    // delete a cookie
    unset: function(name)
    {
        delete this.all[ name ]
    }    
}

```