Testing coroutines with runTest in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a coroutine test using runTest.

Kotlin

import kotlinx.coroutines.test.runTest

fun main() = runTest([1]) {
    // test code here
}

Drag options to blanks, or click blank then click option'

A(

B{

C[

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces directly after runTest without parentheses causes a syntax error.

The runTest function takes a lambda as a parameter, so it requires parentheses before the lambda block.

2fill in blank

medium

Complete the code to launch a coroutine inside runTest.

Kotlin

import kotlinx.coroutines.test.runTest
import kotlinx.coroutines.launch

fun main() = runTest {
    val job = [1] {
        // coroutine work
    }
}

Drag options to blanks, or click blank then click option'

Alaunch

Basync

CrunBlocking

Ddelay

Attempts:

3 left

💡 Hint

Common Mistakes

Using async instead of launch when no result is needed.

Using runBlocking inside runTest causes blocking issues.

Inside runTest, you use launch to start a new coroutine job.

3fill in blank

hard

Fix the error in the test code by completing the runTest call correctly.

Kotlin

import kotlinx.coroutines.test.runTest

fun testSomething() = runTest([1]) {
    // test logic
}

Drag options to blanks, or click blank then click option'

A[

B{

C(

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces directly after runTest without parentheses.

runTest requires parentheses before the lambda block to be called correctly.

4fill in blank

hard

Complete the code to correctly create a test coroutine that delays and asserts a value.

Kotlin

import kotlinx.coroutines.test.runTest
import kotlinx.coroutines.delay
import kotlin.test.assertEquals

fun main() = runTest() {
    delay(100)
    val result = 5
    assertEquals([1], result)
}

Drag options to blanks, or click blank then click option'

A(

B5

C10

D{

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces instead of parentheses for runTest.

Using wrong expected value in assertEquals.

runTest needs parentheses before the lambda, and assertEquals compares expected value 5 to result.

5fill in blank

hard

Fill both blanks to create a test that launches a coroutine, delays, and cancels the job.

Kotlin

import kotlinx.coroutines.test.runTest
import kotlinx.coroutines.launch
import kotlinx.coroutines.delay

fun main() = runTest() {
    val job = [1] {
        delay(1000)
    }
    [2].cancel()
}

Drag options to blanks, or click blank then click option'

A(

Blaunch

Cjob

D{

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces instead of parentheses for runTest.

Using wrong variable name instead of job to cancel.

runTest needs parentheses before the lambda, launch starts the coroutine, and job.cancel() cancels it.