Applying TDD to reverse a number

You've seen Test-Driven Development — now let's apply it! Consider a simple method to reverse an int. If you think in terms of TDD, the first thing you need to do is write a test. Focus on the behavior (input and output) of the method, not on its implementation. This will train you to put the project requirements first.

In the code snippet below, complete the test with the expected output, the expression to obtain the method's actual output, and the expression inside the assertEquals() statement.

Este exercício faz parte do curso

Introduction to Testing in Java

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Instruções do exercício

Enter the correct reversed value for the input number.
Invoke the IntReverser method reverse() to acquire the actual value.
JUnit expects the expected/actual values in a specific order. Enter them into assertEquals().

Exercício interativo prático

Experimente este exercício completando este código de exemplo.

import org.junit.jupiter.api.Test;

import static com.datacamp.util.testing.CustomJUnitTestLauncher.launchTestsAndPrint;
import static org.junit.jupiter.api.Assertions.assertEquals;

public class IntReverser {
    
    public static int reverse(int input) {
        return 0;
    }

    public static class IntReverserTest {
    
        @Test
        public void testReverse_reversesNumber() {
            int input = 1234;
            // Write down the expected return value
            int expected = ____;

			// Call the reverse() method to obtain its actual return value
            int actual = ____;

			// Write the arguments for the assert statement in the correct order
            assertEquals(____);
        }
    }

    public static void main(String[] args) {
		launchTestsAndPrint(IntReverserTest.class);
    }
}

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