Unit testing an angular service method in jasmine

I have a simple angular service which calls a method (this.updateVariable), parses the value received, and updates a variable (myString) with a string.

I want to understand how can i write a unit test to test if the value received is updating a variable with the correct string.

Service:

app.service('myService', function() {

    this.updateVariable = function (status, data) {

        var myString = '';

        if (status.toString()[0] == 4 && data.message !== undefined) {

            if ((data.message.indexOf("Out of spoons") > -1) || (data.message.indexOf("Out of forks")) > -1){
                myString = "Sorry, weve ran out of spoons and/or forks";
            }
            else if (data.message.indexOf("Out of plates") > -1) {
                myString = "Sorry, weve ran out of plates";
            }
            else {
                myString = "We seem to be facing a technical issue";
            }
        }

        if (status.toString()[0] == 9) {
            myString = "Ooops, looks like something is broke.";
        }

        return myString;
    };
});