Kotlin test assertions - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assert that two values are equal.

Kotlin

import kotlin.test.assertEquals

fun testSum() {
    val result = 2 + 3
    assertEquals([1], result)
}

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

A6

B4

C7

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using the actual result as the expected value.

Mixing up the order of arguments in assertEquals.

The assertEquals function checks if the first value equals the second. Here, 2 + 3 equals 5, so we assert 5.

2fill in blank

medium

Complete the code to assert that a condition is true.

Kotlin

import kotlin.test.assertTrue

fun testPositive() {
    val number = 10
    assertTrue([1])
}

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Anumber > 0

Bnumber <= 0

Cnumber == 0

Dnumber < 0

Attempts:

3 left

💡 Hint

Common Mistakes

Using a condition that is false.

Confusing greater than and less than signs.

The assertTrue function checks if the condition is true. Since 10 is greater than 0, number > 0 is correct.

3fill in blank

hard

Fix the error in the assertion that checks if a list is empty.

Kotlin

import kotlin.test.assertTrue

fun testEmptyList() {
    val list = listOf<Int>()
    assertTrue([1])
}

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Alist.size > 0

Blist.isNotEmpty()

Clist.isEmpty()

Dlist.size == 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using isNotEmpty() which checks for non-empty lists.

Checking size incorrectly.

To assert that the list is empty, we use list.isEmpty(). Using list.isNotEmpty() would fail the test.

4fill in blank

hard

Fill both blanks to assert that a string contains a substring and is not empty.

Kotlin

import kotlin.test.assertTrue

fun testString() {
    val text = "Hello Kotlin"
    assertTrue(text.[1]("Kotlin") && text.[2]())
}

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Acontains

BisEmpty

CisNotEmpty

DstartsWith

Attempts:

3 left

💡 Hint

Common Mistakes

Using isEmpty() instead of isNotEmpty().

Using startsWith() which only checks the start of the string.

The code checks if text contains "Kotlin" and is not empty. So, contains and isNotEmpty are correct.

5fill in blank

hard

Fill all three blanks to assert that a map has a key, the value is not null, and the value equals 42.

Kotlin

import kotlin.test.assertTrue

fun testMap() {
    val map = mapOf("answer" to 42)
    assertTrue(map.[1]("answer") && map["answer"] [2] null && map["answer"] [3] 42)
}

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AcontainsKey

B!=

C==

DgetOrDefault

Attempts:

3 left

💡 Hint

Common Mistakes

Using getOrDefault instead of containsKey.

Using == null instead of != null.

Mixing up equality operators.

The code checks if the map contains the key "answer", the value is not null, and the value equals 42. So, containsKey, !=, and == are correct.