A Simple function to determine if a no is prime in Kotlin

IsPrime.kt

import org.testng.Assert
import org.testng.annotations.Test

fun isPrime(num: Int): Boolean {
    val end = kotlin.math.sqrt(num.toDouble()).toInt()

    var i = 2
    while (i < end) {
        if (num % i == 0) {
            return false
        }
        i += 1
    }
    return true
}

class PrimeTest {
    @Test
    fun testPrimeNo() {
        Assert.assertEquals(isPrime(13), true)
        Assert.assertEquals(isPrime(10), false)
    }
}