package com.vogella.junit.first;

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

import org.junit.jupiter.api.Test;

class AClassWithOneJUnitTest {

    @Test
    void demoTestMethod() {
        assertTrue(true);
    }
}

package com.vogella.junit5;

public class Calculator {

    public int multiply(int a, int b) {
        return a * b;
    }
}

package com.vogella.junit5;

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

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

class CalculatorTest {

    Calculator calculator;

    @BeforeEach                                         (1)
    void setUp() {
        calculator = new Calculator();
    }

    @Test                                               (2)
    @DisplayName("Simple multiplication should work")   (3)
    void testMultiply() {
        assertEquals(20, calculator.multiply(4, 5),     (4)
                "Regular multiplication should work");  (5)
    }

    @RepeatedTest(5)                                    (6)
    @DisplayName("Ensure correct handling of zero")
    void testMultiplyWithZero() {
        assertEquals(0, calculator.multiply(0, 5), "Multiple with zero should be zero");
        assertEquals(0, calculator.multiply(5, 0), "Multiple with zero should be zero");
    }
}

**/Test*.java           (1)
**/*Test.java           (2)
**/*Tests.java          (3)
**/*TestCase.java       (4)

// without static imports you have to write the following statement
import org.junit.jupiter.api.Assertions;
// more code
Assert.assertEquals("10 x 5 must be 50", 50, tester.multiply(10, 5));


// alternatively define assertEquals as static import
import static org.junit.jupiter.api.Assertions.assertEquals;
// more code
// use assertEquals directly because of the static import
assertEquals(calculator.multiply(4,5), 20, "Regular multiplication should work");

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

@Test
void exceptionTesting() {
    // set up user
    Throwable exception = assertThrows(IllegalArgumentException.class, () -> user.setAge("23"));
    assertEquals("Age must be an Integer.", exception.getMessage());
}

@Test
void groupedAssertions() {
    Address address = new Address();
    assertAll("address name",
        () -> assertEquals("John", address.getFirstName()),
        () -> assertEquals("User", address.getLastName())
    );
}

=> org.opentest4j.MultipleFailuresError: address name (2 failures)
expected: <John> but was: <null>
expected: <User> but was: <null>

import static org.junit.jupiter.api.Assertions.assertTimeout;
import static java.time.Duration.ofSeconds;
import static java.time.Duration.ofMinutes;

@Test
void timeoutNotExceeded() {
    assertTimeout(ofMinutes(1), () -> service.doBackup());
}

// if you have to check a return value
@Test
void timeoutNotExceededWithResult() {
    String actualResult = assertTimeout(ofSeconds(1), () -> {
        return restService.request(request);
    });
    assertEquals(200, request.getStatus());
}

=> org.opentest4j.AssertionFailedError: execution exceeded timeout of 1000 ms by 212 ms

@Test
void timeoutNotExceededWithResult() {
    String actualResult = assertTimeoutPreemptively(ofSeconds(1), () -> {
        return restService.request(request);
    });
    assertEquals(200, request.getStatus());
}

=> org.opentest4j.AssertionFailedError: execution timed out after 1000 ms

Assumptions.assumeFalse(System.getProperty("os.name").contains("Linux"));

package com.vogella.junit5;

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

import org.junit.jupiter.api.Assumptions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.RepeatedTest;
import org.junit.jupiter.api.Test;

public class CalculatorTest {

    private Calculator calculator;

    @BeforeEach
    void setUp() throws Exception {
        calculator = new Calculator();
    }

    @RepeatedTest(5)
    @DisplayName("Ensure correct handling of zero")
    void testMultiplyWithZero() {
        Assumptions.assumeFalse(System.getProperty("os.name").contains("Linux"));

        assertEquals(calculator.multiply(0,5), 0, "Multiple with zero should be zero");
        assertEquals(calculator.multiply(5,0), 0, "Multiple with zero should be zero");
    }
}

package com.vogella.unittest;

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

import java.util.Arrays;
import java.util.stream.Stream;

import org.junit.jupiter.api.DynamicTest;
import org.junit.jupiter.api.TestFactory;

class DynamicTestCreationTest {

    @TestFactory
    Stream<DynamicTest> testDifferentMultiplyOperations() {
        MyClass tester = new MyClass();
        int[][] data = new int[][] { { 1, 2, 2 }, { 5, 3, 15 }, { 121, 4, 484 } };
        return Arrays.stream(data).map(entry -> {
            int m1 = entry[0];
            int m2 = entry[1];
            int expected = entry[2];
            return dynamicTest(m1 + " * " + m2 + " = " + expected, () -> {
                assertEquals(expected, tester.multiply(m1, m2));
            });
        });
    }

    // class to be tested
    class MyClass {
        public int multiply(int i, int j) {
            return i * j;
        }
    }
}

import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;

public class UsingParameterizedTest {

    public static int[][] data() {
        return new int[][] { { 1 , 2, 2 }, { 5, 3, 15 }, { 121, 4, 484 } };
    }

    @ParameterizedTest
    @MethodSource(value =  "data")
    void testWithStringParameter(int[] data) {
        MyClass tester = new MyClass();
        int m1 = data[0];
        int m2 = data[1];
        int expected = data[2];
        assertEquals(expected, tester.multiply(m1, m2));
    }

    // class to be tested
    class MyClass {
        public int multiply(int i, int j) {
            return i * j;
        }
    }
}

package com.vogella.unittest.sortmethods;

import org.junit.jupiter.api.MethodOrderer.OrderAnnotation;
import org.junit.jupiter.api.Order;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestMethodOrder;

@TestMethodOrder(OrderAnnotation.class)
class OrderAnnotationDemoTest {

    @Test
    @Order(1)
    void firstOne() {
        // test something here
    }

    @Test
    @Order(2)
    void secondOne() {
        // test something here
    }

}

    @Test
    @DisplayName("Ensure that two temporary directories with same files names and content have same hash")
    void hashTwoDynamicDirectoryWhichHaveSameContent(@TempDir Path tempDir, @TempDir Path tempDir2) throws IOException {

        Path file1 = tempDir.resolve("myfile.txt");

        List<String> input = Arrays.asList("input1", "input2", "input3");
        Files.write(file1, input);

        assertTrue(Files.exists(file1), "File should exist");

        Path file2 = tempDir2.resolve("myfile.txt");

        Files.write(file2, input);
        assertTrue(Files.exists(file2), "File should exist");

    }

import org.junit.platform.suite.api.SelectPackages;
import org.junit.platform.suite.api.Suite;
import org.junit.platform.suite.api.SuiteDisplayName;

@Suite
@SuiteDisplayName("JUnit Platform Suite Demo")
@SelectPackages("example")
public class SuiteDemo {
}

package com.vogella.junit.first;

public class MyClass {
    // the following is just an example
  public int multiply(int x, int y) {
    if (x > 999) {
      throw new IllegalArgumentException("X should be less than 1000");
    }
    return x / y;
  }
}

package com.vogella.junit.first;

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

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

class MyClassTest {

    @Test
    void testExceptionIsThrown() {
        MyClass tester = new MyClass();
        assertThrows(IllegalArgumentException.class, () -> tester.multiply(1000, 5));
    }

    @Test
    void testMultiply() {
        MyClass tester = new MyClass();
        assertEquals(50, tester.multiply(10, 5), "10 x 5 must be 50");
    }
}

plugins {
    id 'java'
}

repositories {
    mavenCentral()
}

dependencies {
    testImplementation 'org.junit.jupiter:junit-jupiter:5.7.2'
}

test {
    useJUnitPlatform()

package com.vogella.junit.first;

public class MyClass {
    // the following is just an example
  public int multiply(int x, int y) {
    if (x > 999) {
      throw new IllegalArgumentException("X should be less than 1000");
    }
    return x / y;
  }
}

package com.vogella.junit.first;

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

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

class MyClassTest {

    @Test
    void testExceptionIsThrown() {
        MyClass tester = new MyClass();
        assertThrows(IllegalArgumentException.class, () -> tester.multiply(1000, 5));
    }

    @Test
    void testMultiply() {
        MyClass tester = new MyClass();
        assertEquals(50, tester.multiply(10, 5), "10 x 5 must be 50");
    }
}

package com.vogella.unittest.model;

import java.util.Date;

public class Movie {

    private String title;
    private Date releaseDate;
    @SuppressWarnings("unused")
    private String duration;

    public Movie(String title, Date releaseDate, String duration) {
        super();
        this.title = title;
        this.releaseDate = releaseDate;
        this.duration = duration;
    }

    public String getTitle() {
        return title;
    }

    public Date getReleaseDate() {
        return releaseDate;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + ((releaseDate == null) ? 0 : releaseDate.hashCode());
        result = prime * result + ((title == null) ? 0 : title.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;
        Movie other = (Movie) obj;
        if (releaseDate == null) {
            if (other.releaseDate != null) return false;
        } else if (!releaseDate.equals(other.releaseDate)) return false;
        if (title == null) {
            if (other.title != null) return false;
        } else if (!title.equals(other.title)) return false;
        return true;
    }

}

package com.vogella.unittest.model;

public enum Alignment {
    SUPER_EVIL, EVIL, NEUTRAL, GOOD, SUPER_GOOD;
}

package com.vogella.unittest.model;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
public @interface Magical {

}

package com.vogella.unittest.model;



/**
 * Race in Tolkien's Lord of the Rings.
 *
 * @author Florent Biville
 */
public enum Race {

    HOBBIT("Hobbit", false, Alignment.GOOD), MAIA("Maia", true, Alignment.GOOD), MAN("Man", false, Alignment.NEUTRAL), ELF("Elf", true, Alignment.GOOD), DWARF("Dwarf", false, Alignment.GOOD), ORC("Orc", false, Alignment.EVIL);

    private final String name;
    private final boolean immortal;
    private Alignment alignment;

    Race(String name, boolean immortal, Alignment alignment) {
        this.name = name;
        this.immortal = immortal;
        this.alignment = alignment;
    }

    public String getName() {
        return name;
    }

    public boolean isImmortal() {
        return immortal;
    }

    public Alignment getAlignment() {
        return alignment;
    }

    @Override
    public String toString() {
        return "Race [name=" + name + ", immortal=" + immortal + "]";
    }
}

package com.vogella.unittest.model;

@Magical
public enum Ring {
    oneRing, vilya, nenya, narya, dwarfRing, manRing;

}

package com.vogella.unittest.model;

public class TolkienCharacter {

    // public to test extract on field
    public int age;
    private String name;
    private Race race;
    // not accessible field to test that field by field comparison does not use it
    @SuppressWarnings("unused")
    private long notAccessibleField = System.currentTimeMillis();

    public TolkienCharacter(String name, int age, Race race) {
        this.name = name;
        this.age = age;
        this.race = race;
    }

    public Race getRace() {
        return race;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setAge(int age) {
        if (age<0) {
            throw new IllegalArgumentException("Age is not allowed to be smaller than zero");
        }
        this.age = age;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + age;
        result = prime * result + ((name == null) ? 0 : name.hashCode());
        result = prime * result + ((race == null) ? 0 : race.hashCode());
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;
        TolkienCharacter other = (TolkienCharacter) obj;
        if (age != other.age) return false;
        if (name == null) {
            if (other.name != null) return false;
        } else if (!name.equals(other.name)) return false;
        if (race == null) {
            if (other.race != null) return false;
        } else if (!race.equals(other.race)) return false;
        return true;
    }

    @Override
    public String toString() {
        return name + " " + age + " years old " + race.getName();
    }

}

package com.vogella.unittest.services;

import static com.vogella.unittest.model.Race.DWARF;
import static com.vogella.unittest.model.Race.ELF;
import static com.vogella.unittest.model.Race.HOBBIT;
import static com.vogella.unittest.model.Race.MAIA;
import static com.vogella.unittest.model.Race.MAN;
import static com.vogella.unittest.model.Race.ORC;

import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.vogella.unittest.model.Movie;
import com.vogella.unittest.model.Ring;
import com.vogella.unittest.model.TolkienCharacter;

/**
 * Init data for unit test
 */
public class DataService {

    static final String ERROR_MESSAGE_EXAMPLE_FOR_ASSERTION = "{} assertion : {}\n";


    // Some of the Lord of the Rings characters :
    final TolkienCharacter frodo = new TolkienCharacter("Frodo", 33, HOBBIT);

    final TolkienCharacter sam = new TolkienCharacter("Sam", 38, HOBBIT);

    final TolkienCharacter merry = new TolkienCharacter("Merry", 36, HOBBIT);

    final TolkienCharacter pippin = new TolkienCharacter("Pippin", 28, HOBBIT);

    final TolkienCharacter gandalf = new TolkienCharacter("Gandalf", 2020, MAIA);

    final TolkienCharacter gimli = new TolkienCharacter("Gimli", 139, DWARF);

    final TolkienCharacter legolas = new TolkienCharacter("Legolas", 1000, ELF);

    final TolkienCharacter aragorn = new TolkienCharacter("Aragorn", 87, MAN);

    final TolkienCharacter boromir = new TolkienCharacter("Boromir", 37, MAN);

    final TolkienCharacter sauron = new TolkienCharacter("Sauron", 50000, MAIA);

    final TolkienCharacter galadriel = new TolkienCharacter("Galadriel", 3000, ELF);

    final TolkienCharacter elrond = new TolkienCharacter("Elrond", 3000, ELF);

    final TolkienCharacter guruk = new TolkienCharacter("Guruk", 20, ORC);


    final Movie theFellowshipOfTheRing = new Movie("the fellowship of the Ring", new Date(), "178 min");

    final Movie theTwoTowers = new Movie("the two Towers", new Date(), "179 min");

    final Movie theReturnOfTheKing = new Movie("the Return of the King", new Date(), "201 min");


    public List<TolkienCharacter> getFellowship() {

        final List<TolkienCharacter> fellowshipOfTheRing = new ArrayList<>();


        // let's do some team building :)
        fellowshipOfTheRing.add(frodo);
        fellowshipOfTheRing.add(sam);
        fellowshipOfTheRing.add(merry);
        fellowshipOfTheRing.add(pippin);
        fellowshipOfTheRing.add(gandalf);
        fellowshipOfTheRing.add(legolas);
        fellowshipOfTheRing.add(gimli);
        fellowshipOfTheRing.add(aragorn);
        fellowshipOfTheRing.add(boromir);
        return fellowshipOfTheRing;
    }

    public List<TolkienCharacter> getOrcsWithHobbitPrisoners() {
        final List<TolkienCharacter> orcsWithHobbitPrisoners = new ArrayList<TolkienCharacter>();
        orcsWithHobbitPrisoners.add(guruk);
        orcsWithHobbitPrisoners.add(merry);
        orcsWithHobbitPrisoners.add(pippin);
        return orcsWithHobbitPrisoners;
    }

    public TolkienCharacter getFellowshipCharacter(String name) {
        List<TolkienCharacter> list = getFellowship();
        return list.stream().filter(s-> s.equals(name)).findFirst().get();
    }

    public Map<Ring, TolkienCharacter> getRingBearers() {

         Map<Ring, TolkienCharacter> ringBearers = new HashMap<>();

        // ring bearers
        ringBearers.put(Ring.nenya, galadriel);
        ringBearers.put(Ring.narya, gandalf);
        ringBearers.put(Ring.vilya, elrond);
        ringBearers.put(Ring.oneRing, frodo);
        return  ringBearers;
    }

}

package com.vogella.unittest.services;

import static com.vogella.unittest.model.Race.HOBBIT;
import static org.junit.jupiter.api.Assertions.assertNotNull;
import static org.junit.jupiter.api.Assertions.fail;

import java.util.List;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Tag;
import org.junit.jupiter.api.Test;

import com.vogella.unittest.model.TolkienCharacter;
import com.vogella.unittest.services.DataService;

class DataServiceTest {

    // TODO initialize before each test
    DataService dataService;

    @Test
    void ensureThatInitializationOfTolkeinCharactorsWorks() {
        TolkienCharacter frodo = new TolkienCharacter("Frodo", 33, HOBBIT);

        // TODO check that age is 33
        // TODO check that name is "Frodo"
        // TODO check that name is not "Frodon"
        fail("not yet implemented");
    }

    @Test
    void ensureThatEqualsWorksForCharaters() {
        Object jake = new TolkienCharacter("Jake", 43, HOBBIT);
        Object sameJake = jake;
        Object jakeClone = new TolkienCharacter("Jake", 12, HOBBIT);
        // TODO check that:
        // jake is equal to sameJake
        // jake is not equal to jakeClone
        fail("not yet implemented");
    }

    @Test
    void checkInheritance() {
        TolkienCharacter tolkienCharacter = dataService.getFellowship().get(0);
        // TODO check that tolkienCharacter.getClass is not a movie class
        fail("not yet implemented");
    }

    @Test
    void ensureFellowShipCharacterAccessByNameReturnsNullForUnknownCharacter() {
        // TODO imlement a check that dataService.getFellowshipCharacter returns null for an
        // unknow felllow, e.g. "Lars"
        fail("not yet implemented");
    }

    @Test
    void ensureFellowShipCharacterAccessByNameWorksGivenCorrectNameIsGiven() {
        // TODO imlement a check that dataService.getFellowshipCharacter returns a fellow for an
        // existing felllow, e.g. "Frodo"
        fail("not yet implemented");
    }


    @Test
    void ensureThatFrodoAndGandalfArePartOfTheFellowsip() {

        List<TolkienCharacter> fellowship = dataService.getFellowship();

        // TODO check that Frodo and Gandalf are part of the fellowship
        fail("not yet implemented");
    }

    @Test
    void ensureThatOneRingBearerIsPartOfTheFellowship() {

        List<TolkienCharacter> fellowship = dataService.getFellowship();

        // TODO test that at least one ring bearer is part of the fellowship
        fail("not yet implemented");
    }

    // TODO Use @RepeatedTest(int) to execute this test 1000 times
    @Test
    @Tag("slow")
    @DisplayName("Minimal stress testing: run this test 1000 times to ")
    void ensureThatWeCanRetrieveFellowshipMultipleTimes() {
        dataService = new DataService();
        assertNotNull(dataService.getFellowship());
        fail("this should run 1000 times");
    }

    @Test
    void ensureOrdering() {
        List<TolkienCharacter> fellowship = dataService.getFellowship();

        // ensure that the order of the fellowship is:
        // frodo, sam, merry,pippin, gandalf,legolas,gimli,aragorn,boromir
        fail("not yet implemented");
    }

    @Test
    void ensureAge() {
        List<TolkienCharacter> fellowship = dataService.getFellowship();

        // TODO test ensure that all hobbits and men are younger than 100 years

        // TODO also ensure that the elfs, dwars the maia are all older than 100 years
        fail("not yet implemented");

        // HINT fellowship.stream might be useful here
    }

    @Test
    void ensureThatFellowsStayASmallGroup() {

        List<TolkienCharacter> fellowship = dataService.getFellowship();

        // TODO Write a test to get the 20 element from the fellowship throws an
        // IndexOutOfBoundsException
        fail("not yet implemented");
    }

}

public boolean update() {
    try {
        Thread.sleep(2000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    return true;
}

package com.vogella.unittest.email;


import java.util.regex.Pattern;

public class EmailValidator  {

    /**
     * Email validation pattern.
     */
    public static final Pattern EMAIL_PATTERN = Pattern.compile(
            "[a-zA-Z0-9\\+\\.\\_\\%\\-\\+]{1,256}" +
                    "\\@" +
                    "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,64}" +
                    "(" +
                    "\\." +
                    "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,25}" +
                    ")+"
    );

    private boolean mIsValid = false;

    public boolean isValid() {
        return mIsValid;
    }

    /**
     * Validates if the given input is a valid email address.
     *
     * @param emailPattern The {@link Pattern} used to validate the given email.
     * @param email        The email to validate.
     * @return {@code true} if the input is a valid email. {@code false} otherwise.
     */
    public static boolean isValidEmail(CharSequence email) {
        return email != null && EMAIL_PATTERN.matcher(email).matches();
    }


}

package com.vogella.unittest.email;

import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;
import static org.junit.jupiter.api.Assertions.fail;

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


class EmailValidatorTest {
    // TODO Write test for EmailValidator
    // The names of the methods should give you a pointer what to test for

    @Test
    public void ensureThatEmailValidatorReturnsTrueForValidEmail() {
        assertTrue(EmailValidator.isValidEmail("lars.vogel@gmail.com"));
    }

    @Test
    @DisplayName("Ensure that the usage of a subdomain is still valid, see https://en.wikipedia.org/wiki/Subdomain")
    public void emailValidator_CorrectEmailSubDomain_ReturnsTrue() {
        fail("Fixme");
    }

    @Test
    @DisplayName("Ensure that a missiong top level domain returns false")
    public void emailValidator_InvalidEmailNoTld_ReturnsFalse() {
        fail("Fixme");
    }

    @Test
    public void emailValidator_InvalidEmailDoubleDot_ReturnsFalse() {
        fail("Fixme");
    }

    @Test
    public void emailValidator_InvalidEmailNoUsername_ReturnsFalse() {
        fail("Fixme");
    }

    @Test
    public void emailValidator_EmptyString_ReturnsFalse() {
        fail("Fixme");
    }

    @Test
    public void emailValidator_NullEmail_ReturnsFalse() {
        fail("Fixme");
    }

}

package com.vogella.unittest.services;


import static com.vogella.unittest.model.Race.HOBBIT;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;
import static org.junit.jupiter.api.Assertions.fail;

import org.junit.jupiter.api.Disabled;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

import com.vogella.unittest.model.TolkienCharacter;


public class DataModelAssertThrowsTest {

    @Test
    @DisplayName("Ensure that access to the fellowship throws exception outside the valid range")
    void exceptionTesting() {
        DataService dataService = new DataService();
        Throwable exception = assertThrows(IndexOutOfBoundsException.class, () -> dataService.getFellowship().get(20));
        assertEquals("Index 20 out of bounds for length 9", exception.getMessage());
    }

    @Test
    @Disabled("Please fix and enable")
    public void ensureThatAgeMustBeLargerThanZeroViaSetter() {
        TolkienCharacter frodo = new TolkienCharacter("Frodo", 33, HOBBIT);
        // use assertThrows() rule to check that the message is:
        // Age is not allowed to be smaller than zero
        frodo.setAge(-1);

    }

    @Test
    @Disabled("Please fix and enable")
    public void testThatAgeMustBeLargerThanZeroViaConstructor() {
        // use assertThrows() rule to check that an IllegalArgumentException exception is thrown and
        // that the message is:
        // "Age is not allowed to be smaller than zero"

        TolkienCharacter frodo = new TolkienCharacter("Frodo", -1, HOBBIT);

    }

}

package com.vogella.unittest.platform;

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

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

class LinuxTests {
    @Test
    void testName() throws Exception {
        // only run on Linux
        Assumptions.assumeTrue(System.getProperty("os.name").contains("Linux"));
        assertTrue(true);
    }
}

package com.vogella.unittest.nested;
import static org.junit.jupiter.api.Assertions.assertEquals;

import java.util.Arrays;
import java.util.List;

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

class UsingNestedTests {

    private List<String> list;

    @BeforeEach
    void setup() {
        list = Arrays.asList("JUnit 5", "Mockito");
    }

    @Test
    void listTests() {
        assertEquals(2, list.size());
    }

    // TODO define inner class with @Nestled
    // write one tests named checkFirstElement() to check that the first list element is "JUnit 4"
    // write one tests named checkSecondElement() to check that the first list element is "JUnit 4"
    @DisplayName("Grouped tests for checking members")
    @Nested
    class CheckMembers {
        @Test
        void checkFirstElement() {
            assertEquals(("JUnit 5"), list.get(0));
        }

        @Test
        void checkSecondElement() {
            assertEquals(("Mockito"), list.get(1));
        }

    }

}

package com.vogella.unittest.converter;

public class ConverterUtil {
    // converts to celsius
    public static float convertFahrenheitToCelsius(float fahrenheit) {
        return ((fahrenheit - 32) * 5 / 9);
    }

    // converts to fahrenheit
    public static float convertCelsiusToFahrenheit(float celsius) {
        return ((celsius * 9) / 5) + 32;
    }
}

package com.vogella.unittest.converter;

import java.util.Arrays;
import java.util.stream.Stream;

import org.junit.jupiter.api.DynamicTest;
import org.junit.jupiter.api.TestFactory;

class ConverterUtilTest {

    int[][] celsiusFahrenheitMapping = new int[][] { { 10, 50 }, { 40, 104 }, { 0, 32 } };

    @TestFactory
    Stream<DynamicTest> ensureThatCelsiumConvertsToFahrenheit() {
        return Arrays.stream(celsiusFahrenheitMapping).map(entry -> {
            // access celcius and fahrenheit from entry
            int celsius = entry[0];
            int fahrenheit = entry[1];
            return null;
            // return a dynamicTest which checks that that the convertion from celcius to
            // fahrenheit is correct
        });

    }

    Stream<DynamicTest> ensureThatFahrenheitToCelsiumConverts() {
        return null;
        // TODO Write a similar test fahrenheit to celsius
    }
}

    org.junit.jupiter
    junit-jupiter-params
    5.7.2
    test

implementation 'org.junit.jupiter:junit-jupiter-params:5.7.2'

package com.vogella.unittest.converter;
import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;

class ParameterizedExampleTest {

    static int[][] data() {
        return new int[][] { { 1 , 2, 2 }, { 5, 3, 15 }, { 121, 4, 484 } };
    }

    @ParameterizedTest(name = "{index} called with: {0}")
    @MethodSource(value =  "data")
    void testWithStringParameter(int[] data) {
        MyClass tester = new MyClass();
        int m1 = data[0];
        int m2 = data[1];
        int expected = data[2];
        assertEquals(expected, tester.multiply(m1, m2));
    }

    // class to be tested
    class MyClass {
        public int multiply(int i, int j) {
            return i * j;
        }
    }
}

    @ParameterizedTest
    @ValueSource(strings = { "WINDOW", "Microsoft Windows [Version 10.?]" })
    void ensureWindowsStringContainWindow(String name) {
        assertTrue(name.toLowerCase().contains("window"));
    }

    @DisplayName("A negative value for year is not supported by the leap year computation.")
    @ParameterizedTest(name = "For example, year {0} is not supported.")
    @ValueSource(ints = { -1, -4 })
    void ensureYear(int year) {
        assertTrue(year < 0);
    }

    @ParameterizedTest(name = "{0} * {1} = {2}")
    @CsvSource({ "0,    1,   0", "1,    2,   2", "49,  50, 2450", "1,  100, 100" })
    void add(int first, int second, int expectedResult) {
        MyClass calculator = new MyClass();
        assertEquals(expectedResult, calculator.multiply(first, second),
                () -> first + " * " + second + " should equal " + expectedResult);
    }

package com.vogella.unittest.file;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;

public class FileWriter {
    private FileWriter() {

    }

    public static void createFile(Path path) {
        try {
            Files.write(path, "".getBytes(StandardCharsets.UTF_8), StandardOpenOption.CREATE,
                    StandardOpenOption.TRUNCATE_EXISTING);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void appendFile(Path path, String content) throws IOException {
        // image more logic here...
        Files.writeString(path, content, StandardOpenOption.APPEND);
    }
}

@Test
void ensureThatPathFromTempDirISWritable(@TempDir Path path) {
    // Check if the path created by the TempDir extension is writable
    // Check `Files` API for this
}

<dependency>
  <groupId>javax.inject</groupId>
  <artifactId>javax.inject</artifactId>
  <version>1</version>
</dependency>

implementation 'javax.inject:javax.inject:1'

package com.vogella.unittest.di;

import javax.inject.Inject;

public class Service {

    @Inject
    String s;

    @Inject
    public Service() {
    }

    @Inject
    public Service(String s) {
        this.s = s;
    }
}