Pay attention to the names of the unit tests; your task is to implement them so that they perform the function indicated in the name.

At the beginning of each test, you need to create an instance of the ExceptionHandlingExercise class.

It will look like this: ExceptionHandlingExercise exercise = new ExceptionHandlingExercise();.

Next, you need to create a variable that will hold the value you want to test. For example: int underage = 17;.

Use the assertions you learned in the previous chapter.

You can optionally write additional tests for the functionality of these methods.

package codefinity;

import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
import org.junit.jupiter.api.Test;

public class ExceptionHandlingExerciseTest {

    @Test
    public void checkAge_ShouldThrowIllegalArgumentException_WhenAgeIsLessThan18() {
        ExceptionHandlingExercise exercise = new ExceptionHandlingExercise();
        int underage = 17;

        assertThrows(IllegalArgumentException.class, () -> {
            exercise.checkAge(underage);
        });
    }

    @Test
    public void checkAge_ShouldNotThrowException_WhenAgeIs18OrMore() {
        ExceptionHandlingExercise exercise = new ExceptionHandlingExercise();
        int legalAge = 18;

        assertDoesNotThrow(() -> {
            exercise.checkAge(legalAge);
        });
    }

    @Test
    public void printLength_ShouldThrowNullPointerException_WhenStringIsNull() {
        ExceptionHandlingExercise exercise = new ExceptionHandlingExercise();
        String nullString = null;

        assertThrows(NullPointerException.class, () -> {
            exercise.printLength(nullString);
        });
    }

    @Test
    public void printLength_ShouldNotThrowException_WhenStringIsNotNull() {
        ExceptionHandlingExercise exercise = new ExceptionHandlingExercise();
        String nonNullString = "JUnit";

        assertDoesNotThrow(() -> {
            exercise.printLength(nonNullString);
        });
    }
}