Writing test cases for Math.Random(); codewars kata

I am authoring my first simple Kata on Codewars. The objective of the Kata is to fix the code.
This is the complete working solution,

function yourFutureCareer() {
  var career = Math.random();
    if (career <= 0.32) {
        return 'FrontEnd Developer';
    } else if (career <= 0.65) {
        return 'BackEnd Developer';
    } else {
        return 'Full-Stack Developer';
    } 
} 

yourFutureCareer();

This is initial solution the user will work on,

function {
var : Math.random();
    if (career <= 0.32) {
        return = FrontEnd Developer
     else if (career <= 0.65) 
        return : BackEnd Developer,
    } else {
        return 'Full-Stack Developer'
    }

    yourFutureCareer();

In order to publish the Kata, I have to provide Test Cases that will determine if the solution is valid or not. I've tried writing a first Test Case,

Test.assertSimilar(yourFutureCareer(), yourFutureCareer(), 'true')

Sometimes the test fails,

Expected: FrontEnd Developer, instead got: BackEnd Developer

Sometimes the test passes,

Test Passed: Value == Full-Stack Developer

So, how to write test cases so that the solution can be validated? Any example code or sample would be helpful.