WildCoderTDD

StringUtils.java

package fr.wildcodeschool.unittesting;

    public class StringUtils {

        private static final String ALL_VOWELS = "aeiouyAEIOUY";

        /**
         * Renvoie la chaine formée par les voyelles d'une chaine de caractères
         * @return Chaine avec uniquement des voyelles
         */
        public static String vowels(String candidate) {
            if (candidate == null) throw new IllegalArgumentException("The candidate string is null.");
            String vowels = "";
            char[] letters = candidate.toCharArray();
            for (int i = 0; i < candidate.length(); i++) {
                if (ALL_VOWELS.indexOf(letters[i]) >= 0 && vowels.indexOf(letters[i]) == -1) {
                    vowels += letters[i];
                }
            }
            return vowels;
        }

    }

StringUtilsTest.java

package fr.wildcodeschool.unittesting;

import org.junit.Test;
import org.junit.jupiter.api.BeforeEach;

import static org.junit.jupiter.api.Assertions.assertEquals;

public class StringUtilsTest {

    private StringUtils stringUtilsInstance;

    @BeforeEach
    public void setup(){
        stringUtilsInstance = new StringUtils();
    }

    @Test
    public void voyelsTakesTheFirstCharacterIntoAccount(){
        String testedString = "ABOEI";
        assertEquals("AOEI", StringUtils.vowels(testedString));
    }

    @Test
    public void voyelsTakesLowercaseLetterYIntoAccount(){
        String testedString = "aybcne";
        assertEquals("aye", StringUtils.vowels(testedString));
    }

    @Test
    public void voyelsTakesUppercaseLetterYIntoAccount(){
        String testedString = "AYBNCE";
        assertEquals("AYE", StringUtils.vowels(testedString));
    }

    @Test
    public void voyelsWithSeveralInstancesOfSameVoyelReturnsItOnce(){
        assertEquals("A", StringUtils.vowels("AAAA"));
    }

    @Test
    public void voyelsWithEmptyStringReturnsEmptyString(){
        assertEquals("", StringUtils.vowels(""));
    }

    @Test(expected = IllegalArgumentException.class)
    public void voyelsThrowExceptionIfParameterNotGiven(){
        StringUtils.vowels(null);
    }


}