This Kotlin Online Test
Separates Good From Bad Hires

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About the test

The Kotlin online test assesses candidates' knowledge of programming in the Kotlin language and their ability to leverage commonly used parts of the Kotlin and Java standard libraries.

It's an ideal test for pre-employment screening. A good Kotlin developer needs to be able not only to solve problems using Kotlin but also recognize when to leverage the functionality of its features, such as nullable types, coroutines, and infix functions.

This online test requires candidates to answer multiple choice questions and understand Kotlin code.

Sample public questions

3 min
Infix Functions

Consider the following code used to check whether two materials are compatible to use in a construction project:

enum class Category {

data class Material (val category: Category)

// Extension infix function.
infix fun Material.compatibleWith(other: Material) : Boolean {
    return this.category == Category.LIGHT || other.category == Category.FILLER;

fun main() {
    val mat1 = Material(Category.HEAVY)
    val mat2 = Material(Category.LIGHT)
    // Use mat1 and mat2 here.

What is correct about the compatibleWith function?

3 min
Null Safety

The following Kotlin code is used in a toy drone to adjust its movement:

fun adjust(vertical: Int?, horizontal: Int?) : Unit {
    if (vertical == null) {
        println("Didn't get vertical information")
    } else {
        // Controls the drone with amplified vertical movements
        move(vertical * 2, horizontal!!)
    log_movement(vertical ?: -1, horizontal ?: -1)

Select the correct answers about the adjust function.

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Skills and topics tested

  • Kotlin
  • Inheritance
  • Method Overriding
  • OOP
  • Coroutines
  • Exceptions
  • Enum

For job roles

  • Back-End Developer
  • Kotlin Developer
  • Web Developer

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