Why testing matters in Kotlin - See It in Action

Why testing matters

📖 Scenario: Imagine you are building a simple calculator app that adds two numbers. You want to make sure your addition works correctly every time, even if you change your code later.

🎯 Goal: You will create a small Kotlin program that adds two numbers and write a simple test function to check if the addition works correctly. This will show why testing your code is important.

📋 What You'll Learn

Create two variables with exact values

Create a function to add two numbers

Create a test function to check the addition

Print the test result

💡 Why This Matters

🌍 Real World

Testing helps developers make sure their apps work correctly before users see them. It saves time and avoids bugs.

💼 Career

Writing tests is a key skill for software developers. It shows you can write reliable and maintainable code.

1

DATA SETUP: Create two variables with exact values

Create two variables called num1 and num2 with values 5 and 7 respectively.

Kotlin

# Create two variables num1 and num2 with values 5 and 7
// Your code here

Need a hint?

Use val to create variables and assign the numbers 5 and 7.

2

CONFIGURATION: Create a function to add two numbers

Create a function called add that takes two Int parameters named a and b and returns their sum.

Kotlin

val num1 = 5
val num2 = 7

// Create a function add(a: Int, b: Int): Int that returns a + b
// Your code here

Need a hint?

Define a function with fun keyword and return the sum of a and b.

3

CORE LOGIC: Create a test function to check the addition

Create a function called testAdd that calls add(num1, num2) and checks if the result equals 12. Store the check result in a variable called testPassed.

Kotlin

val num1 = 5
val num2 = 7

fun add(a: Int, b: Int): Int {
    return a + b
}

// Create a function testAdd() that checks if add(num1, num2) == 12
// Your code here

Need a hint?

Inside testAdd, call add(num1, num2) and compare it to 12 using ==.

4

OUTPUT: Print the test result

Inside the testAdd function, add a line to print "Test passed!" if testPassed is true, otherwise print "Test failed!". Then call testAdd().

Kotlin

val num1 = 5
val num2 = 7

fun add(a: Int, b: Int): Int {
    return a + b
}

fun testAdd() {
    val testPassed = add(num1, num2) == 12
    // Print "Test passed!" if testPassed is true, else "Test failed!"
}

// Call testAdd()
// Your code here

Need a hint?

Use an if statement to print the correct message based on testPassed. Then call testAdd() to run the test.