[BAEL-9555] - Created a core-java-modules folder

core-java-modules/core-java-lang/src/test/java/com/baeldung/binding/AnimalActivityUnitTest.java

@@ -0,0 +1,95 @@
+package com.baeldung.binding;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.spi.LoggingEvent;
+import ch.qos.logback.core.Appender;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.slf4j.LoggerFactory;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import static org.mockito.Mockito.verify;
+
+/**
+ *https://gist.github.com/bloodredsun/a041de13e57bf3c6c040
+ */
+@RunWith(MockitoJUnitRunner.class)
+
+public class AnimalActivityUnitTest {
+
+    @Mock
+    private Appender mockAppender;
+    @Captor
+    private ArgumentCaptor<LoggingEvent> captorLoggingEvent;
+
+    @Before
+    public void setup() {
+        final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
+        logger.addAppender(mockAppender);
+    }
+
+    @After
+    public void teardown() {
+        final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
+        logger.detachAppender(mockAppender);
+    }
+
+    @Test
+    public void givenAnimalReference__whenRefersAnimalObject_shouldCallFunctionWithAnimalParam() {
+
+        Animal animal = new Animal();
+
+        AnimalActivity.sleep(animal);
+
+        verify(mockAppender).doAppend(captorLoggingEvent.capture());
+
+        final LoggingEvent loggingEvent = captorLoggingEvent.getValue();
+
+        assertThat(loggingEvent.getLevel(), is(Level.INFO));
+
+        assertThat(loggingEvent.getFormattedMessage(),
+                is("Animal is sleeping"));
+    }
+
+    @Test
+    public void givenDogReference__whenRefersCatObject_shouldCallFunctionWithAnimalParam() {
+
+        Cat cat = new Cat();
+
+        AnimalActivity.sleep(cat);
+
+        verify(mockAppender).doAppend(captorLoggingEvent.capture());
+
+        final LoggingEvent loggingEvent = captorLoggingEvent.getValue();
+
+        assertThat(loggingEvent.getLevel(), is(Level.INFO));
+
+        assertThat(loggingEvent.getFormattedMessage(),
+                is("Cat is sleeping"));
+    }
+
+    @Test
+    public void givenAnimaReference__whenRefersDogObject_shouldCallFunctionWithAnimalParam() {
+
+        Animal cat = new Cat();
+
+        AnimalActivity.sleep(cat);
+
+        verify(mockAppender).doAppend(captorLoggingEvent.capture());
+
+        final LoggingEvent loggingEvent = captorLoggingEvent.getValue();
+
+        assertThat(loggingEvent.getLevel(), is(Level.INFO));
+
+        assertThat(loggingEvent.getFormattedMessage(),
+                is("Animal is sleeping"));
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/binding/AnimalUnitTest.java

@@ -0,0 +1,87 @@
+package com.baeldung.binding;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.spi.LoggingEvent;
+import ch.qos.logback.core.Appender;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.slf4j.LoggerFactory;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import java.util.List;
+
+/**
+ * Created by madhumita.g on 01-08-2018.
+ */
+
+@RunWith(MockitoJUnitRunner.class)
+public class AnimalUnitTest {
+    @Mock
+    private Appender mockAppender;
+    @Captor
+    private ArgumentCaptor<LoggingEvent> captorLoggingEvent;
+
+    @Before
+    public void setup() {
+        final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
+        logger.addAppender(mockAppender);
+    }
+
+    @After
+    public void teardown() {
+        final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
+        logger.detachAppender(mockAppender);
+    }
+
+    @Test
+    public void whenCalledWithoutParameters_shouldCallFunctionMakeNoiseWithoutParameters() {
+
+        Animal animal = new Animal();
+
+        animal.makeNoise();
+
+        verify(mockAppender).doAppend(captorLoggingEvent.capture());
+
+        final LoggingEvent loggingEvent = captorLoggingEvent.getValue();
+
+        assertThat(loggingEvent.getLevel(), is(Level.INFO));
+
+        assertThat(loggingEvent.getFormattedMessage(),
+                is("generic animal noise"));
+    }
+
+    @Test
+    public void whenCalledWithParameters_shouldCallFunctionMakeNoiseWithParameters() {
+
+        Animal animal = new Animal();
+
+        int testValue = 3;
+        animal.makeNoise(testValue);
+
+        verify(mockAppender,times(3)).doAppend(captorLoggingEvent.capture());
+
+        final List<LoggingEvent> loggingEvents = captorLoggingEvent.getAllValues();
+
+        for(LoggingEvent loggingEvent : loggingEvents)
+        {
+            assertThat(loggingEvent.getLevel(), is(Level.INFO));
+
+            assertThat(loggingEvent.getFormattedMessage(),
+                    is("generic animal noise countdown "+testValue));
+
+            testValue--;
+        }
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/binding/CatUnitTest.java

@@ -0,0 +1,62 @@
+package com.baeldung.binding;
+
+import ch.qos.logback.classic.Level;
+import ch.qos.logback.classic.Logger;
+import ch.qos.logback.classic.spi.LoggingEvent;
+import ch.qos.logback.core.Appender;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Captor;
+import org.mockito.Mock;
+import org.mockito.junit.MockitoJUnitRunner;
+import org.slf4j.LoggerFactory;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+import static org.mockito.Mockito.verify;
+
+/**
+ * Created by madhumita.g on 01-08-2018.
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class CatUnitTest {
+
+    @Mock
+    private Appender mockAppender;
+
+    @Captor
+    private ArgumentCaptor<LoggingEvent> captorLoggingEvent;
+
+    @Before
+    public void setup() {
+        final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
+        logger.addAppender(mockAppender);
+    }
+
+    @After
+    public void teardown() {
+        final Logger logger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
+        logger.detachAppender(mockAppender);
+    }
+
+    @Test
+    public void makeNoiseTest() {
+
+        Cat cat = new Cat();
+
+        cat.makeNoise();
+
+        verify(mockAppender).doAppend(captorLoggingEvent.capture());
+
+        final LoggingEvent loggingEvent = captorLoggingEvent.getValue();
+
+        assertThat(loggingEvent.getLevel(), is(Level.INFO));
+
+        assertThat(loggingEvent.getFormattedMessage(),
+                is("meow"));
+
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/className/RetrievingClassNameUnitTest.java

@@ -0,0 +1,156 @@
+package com.baeldung.className;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+public class RetrievingClassNameUnitTest {
+
+    // Retrieving Simple Name
+    @Test
+    public void givenRetrievingClassName_whenGetSimpleName_thenRetrievingClassName() {
+        assertEquals("RetrievingClassName", RetrievingClassName.class.getSimpleName());
+    }
+
+    @Test
+    public void givenPrimitiveInt_whenGetSimpleName_thenInt() {
+        assertEquals("int", int.class.getSimpleName());
+    }
+
+    @Test
+    public void givenRetrievingClassNameArray_whenGetSimpleName_thenRetrievingClassNameWithBrackets() {
+        assertEquals("RetrievingClassName[]", RetrievingClassName[].class.getSimpleName());
+        assertEquals("RetrievingClassName[][]", RetrievingClassName[][].class.getSimpleName());
+    }
+
+    @Test
+    public void givenAnonymousClass_whenGetSimpleName_thenEmptyString() {
+        assertEquals("", new RetrievingClassName() {}.getClass().getSimpleName());
+    }
+
+    // Retrieving Other Names
+    // - Primitive Types
+    @Test
+    public void givenPrimitiveInt_whenGetName_thenInt() {
+        assertEquals("int", int.class.getName());
+    }
+
+    @Test
+    public void givenPrimitiveInt_whenGetTypeName_thenInt() {
+        assertEquals("int", int.class.getTypeName());
+    }
+
+    @Test
+    public void givenPrimitiveInt_whenGetCanonicalName_thenInt() {
+        assertEquals("int", int.class.getCanonicalName());
+    }
+
+    // - Object Types
+    @Test
+    public void givenRetrievingClassName_whenGetName_thenCanonicalName() {
+        assertEquals("com.baeldung.className.RetrievingClassName", RetrievingClassName.class.getName());
+    }
+
+    @Test
+    public void givenRetrievingClassName_whenGetTypeName_thenCanonicalName() {
+        assertEquals("com.baeldung.className.RetrievingClassName", RetrievingClassName.class.getTypeName());
+    }
+
+    @Test
+    public void givenRetrievingClassName_whenGetCanonicalName_thenCanonicalName() {
+        assertEquals("com.baeldung.className.RetrievingClassName", RetrievingClassName.class.getCanonicalName());
+    }
+
+    // - Inner Classes
+    @Test
+    public void givenRetrievingClassNameInnerClass_whenGetName_thenCanonicalNameWithDollarSeparator() {
+        assertEquals("com.baeldung.className.RetrievingClassName$InnerClass", RetrievingClassName.InnerClass.class.getName());
+    }
+
+    @Test
+    public void givenRetrievingClassNameInnerClass_whenGetTypeName_thenCanonicalNameWithDollarSeparator() {
+        assertEquals("com.baeldung.className.RetrievingClassName$InnerClass", RetrievingClassName.InnerClass.class.getTypeName());
+    }
+
+    @Test
+    public void givenRetrievingClassNameInnerClass_whenGetCanonicalName_thenCanonicalName() {
+        assertEquals("com.baeldung.className.RetrievingClassName.InnerClass", RetrievingClassName.InnerClass.class.getCanonicalName());
+    }
+
+    // - Anonymous Classes
+    @Test
+    public void givenAnonymousClass_whenGetName_thenCallingClassCanonicalNameWithDollarSeparatorAndCountNumber() {
+        // These are the second and third appearences of an anonymous class in RetrievingClassNameUnitTest, hence $2 and $3 expectations
+        assertEquals("com.baeldung.className.RetrievingClassNameUnitTest$2", new RetrievingClassName() {}.getClass().getName());
+        assertEquals("com.baeldung.className.RetrievingClassNameUnitTest$3", new RetrievingClassName() {}.getClass().getName());
+    }
+
+    @Test
+    public void givenAnonymousClass_whenGetTypeName_thenCallingClassCanonicalNameWithDollarSeparatorAndCountNumber() {
+        // These are the fourth and fifth appearences of an anonymous class in RetrievingClassNameUnitTest, hence $4 and $5 expectations
+        assertEquals("com.baeldung.className.RetrievingClassNameUnitTest$4", new RetrievingClassName() {}.getClass().getTypeName());
+        assertEquals("com.baeldung.className.RetrievingClassNameUnitTest$5", new RetrievingClassName() {}.getClass().getTypeName());
+    }
+
+    @Test
+    public void givenAnonymousClass_whenGetCanonicalName_thenNull() {
+        assertNull(new RetrievingClassName() {}.getClass().getCanonicalName());
+    }
+
+    // - Arrays
+    @Test
+    public void givenPrimitiveIntArray_whenGetName_thenOpeningBracketsAndPrimitiveIntLetter() {
+        assertEquals("[I", int[].class.getName());
+        assertEquals("[[I", int[][].class.getName());
+    }
+
+    @Test
+    public void givenRetrievingClassNameArray_whenGetName_thenOpeningBracketsLetterLAndRetrievingClassNameGetName() {
+        assertEquals("[Lcom.baeldung.className.RetrievingClassName;", RetrievingClassName[].class.getName());
+        assertEquals("[[Lcom.baeldung.className.RetrievingClassName;", RetrievingClassName[][].class.getName());
+    }
+
+    @Test
+    public void givenRetrievingClassNameInnerClassArray_whenGetName_thenOpeningBracketsLetterLAndRetrievingClassNameInnerClassGetName() {
+        assertEquals("[Lcom.baeldung.className.RetrievingClassName$InnerClass;", RetrievingClassName.InnerClass[].class.getName());
+        assertEquals("[[Lcom.baeldung.className.RetrievingClassName$InnerClass;", RetrievingClassName.InnerClass[][].class.getName());
+    }
+
+    @Test
+    public void givenPrimitiveIntArray_whenGetTypeName_thenPrimitiveIntGetTypeNameWithBrackets() {
+        assertEquals("int[]", int[].class.getTypeName());
+        assertEquals("int[][]", int[][].class.getTypeName());
+    }
+
+    @Test
+    public void givenRetrievingClassNameArray_whenGetTypeName_thenRetrievingClassNameGetTypeNameWithBrackets() {
+        assertEquals("com.baeldung.className.RetrievingClassName[]", RetrievingClassName[].class.getTypeName());
+        assertEquals("com.baeldung.className.RetrievingClassName[][]", RetrievingClassName[][].class.getTypeName());
+    }
+
+    @Test
+    public void givenRetrievingClassNameInnerClassArray_whenGetTypeName_thenRetrievingClassNameInnerClassGetTypeNameWithBrackets() {
+        assertEquals("com.baeldung.className.RetrievingClassName$InnerClass[]", RetrievingClassName.InnerClass[].class.getTypeName());
+        assertEquals("com.baeldung.className.RetrievingClassName$InnerClass[][]", RetrievingClassName.InnerClass[][].class.getTypeName());
+    }
+
+    @Test
+    public void givenPrimitiveIntArray_whenGetCanonicalName_thenPrimitiveIntGetCanonicalNameWithBrackets() {
+        assertEquals("int[]", int[].class.getCanonicalName());
+        assertEquals("int[][]", int[][].class.getCanonicalName());
+    }
+
+    @Test
+    public void givenRetrievingClassNameArray_whenGetCanonicalName_thenRetrievingClassNameGetCanonicalNameWithBrackets() {
+        assertEquals("com.baeldung.className.RetrievingClassName[]", RetrievingClassName[].class.getCanonicalName());
+        assertEquals("com.baeldung.className.RetrievingClassName[][]", RetrievingClassName[][].class.getCanonicalName());
+    }
+
+    @Test
+    public void givenRetrievingClassNameInnerClassArray_whenGetCanonicalName_thenRetrievingClassNameInnerClassGetCanonicalNameWithBrackets() {
+        assertEquals("com.baeldung.className.RetrievingClassName.InnerClass[]", RetrievingClassName.InnerClass[].class.getCanonicalName());
+        assertEquals("com.baeldung.className.RetrievingClassName.InnerClass[][]", RetrievingClassName.InnerClass[][].class.getCanonicalName());
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/classnotfoundexception/ClassNotFoundExceptionUnitTest.java

@@ -0,0 +1,11 @@
+package com.baeldung.classnotfoundexception;
+
+import org.junit.Test;
+
+public class ClassNotFoundExceptionUnitTest {
+
+    @Test(expected = ClassNotFoundException.class)
+    public void givenNoDriversInClassPath_whenLoadDrivers_thenClassNotFoundException() throws ClassNotFoundException {
+        Class.forName("oracle.jdbc.driver.OracleDriver");
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/comparable/ComparableUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.comparable;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import org.junit.Test;
+
+public class ComparableUnitTest {
+
+    @Test
+    public void whenUsingComparable_thenSortedList() {
+        List<Player> footballTeam = new ArrayList<Player>();
+        Player player1 = new Player(59, "John", 20);
+        Player player2 = new Player(67, "Roger", 22);
+        Player player3 = new Player(45, "Steven", 24);
+        footballTeam.add(player1);
+        footballTeam.add(player2);
+        footballTeam.add(player3);
+        Collections.sort(footballTeam);
+        assertEquals(footballTeam.get(0)
+            .getName(), "Steven");
+        assertEquals(footballTeam.get(2)
+            .getRanking(), 67);
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/comparator/ComparatorUnitTest.java

@@ -0,0 +1,47 @@
+package com.baeldung.comparator;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class ComparatorUnitTest {
+
+    List<Player> footballTeam;
+
+    @Before
+    public void setUp() {
+        footballTeam = new ArrayList<Player>();
+        Player player1 = new Player(59, "John", 20);
+        Player player2 = new Player(67, "Roger", 22);
+        Player player3 = new Player(45, "Steven", 24);
+        footballTeam.add(player1);
+        footballTeam.add(player2);
+        footballTeam.add(player3);
+    }
+
+    @Test
+    public void whenUsingRankingComparator_thenSortedList() {
+        PlayerRankingComparator playerComparator = new PlayerRankingComparator();
+        Collections.sort(footballTeam, playerComparator);
+        assertEquals(footballTeam.get(0)
+            .getName(), "Steven");
+        assertEquals(footballTeam.get(2)
+            .getRanking(), 67);
+    }
+
+    @Test
+    public void whenUsingAgeComparator_thenSortedList() {
+        PlayerAgeComparator playerComparator = new PlayerAgeComparator();
+        Collections.sort(footballTeam, playerComparator);
+        assertEquals(footballTeam.get(0)
+            .getName(), "John");
+        assertEquals(footballTeam.get(2)
+            .getRanking(), 45);
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/comparator/Java8ComparatorUnitTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.comparator;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class Java8ComparatorUnitTest {
+
+    List<Player> footballTeam;
+
+    @Before
+    public void setUp() {
+        footballTeam = new ArrayList<Player>();
+        Player player1 = new Player(59, "John", 22);
+        Player player2 = new Player(67, "Roger", 20);
+        Player player3 = new Player(45, "Steven", 24);
+        footballTeam.add(player1);
+        footballTeam.add(player2);
+        footballTeam.add(player3);
+    }
+
+    @Test
+    public void whenComparing_UsingLambda_thenSorted() {
+        System.out.println("************** Java 8 Comaparator **************");
+        Comparator<Player> byRanking = (Player player1, Player player2) -> player1.getRanking() - player2.getRanking();
+
+        System.out.println("Before Sorting : " + footballTeam);
+        Collections.sort(footballTeam, byRanking);
+        System.out.println("After Sorting : " + footballTeam);
+        assertEquals(footballTeam.get(0)
+            .getName(), "Steven");
+        assertEquals(footballTeam.get(2)
+            .getRanking(), 67);
+    }
+
+    @Test
+    public void whenComparing_UsingComparatorComparing_thenSorted() {
+        System.out.println("********* Comaparator.comparing method *********");
+        System.out.println("********* byRanking *********");
+        Comparator<Player> byRanking = Comparator.comparing(Player::getRanking);
+
+        System.out.println("Before Sorting : " + footballTeam);
+        Collections.sort(footballTeam, byRanking);
+        System.out.println("After Sorting : " + footballTeam);
+        assertEquals(footballTeam.get(0)
+            .getName(), "Steven");
+        assertEquals(footballTeam.get(2)
+            .getRanking(), 67);
+        
+        System.out.println("********* byAge *********");
+        Comparator<Player> byAge = Comparator.comparing(Player::getAge);
+
+        System.out.println("Before Sorting : " + footballTeam);
+        Collections.sort(footballTeam, byAge);
+        System.out.println("After Sorting : " + footballTeam);
+        assertEquals(footballTeam.get(0)
+            .getName(), "Roger");
+        assertEquals(footballTeam.get(2)
+            .getRanking(), 45);
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/compoundoperators/CompoundOperatorsUnitTest.java

@@ -0,0 +1,111 @@
+package com.baeldung.compoundoperators;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class CompoundOperatorsUnitTest {
+
+    @Test
+    public void whenAssignmentOperatorIsUsed_thenValueIsAssigned() {
+        int x = 5;
+
+        assertEquals(5, x);
+    }
+
+    @Test
+    public void whenCompoundAssignmentUsed_thenSameAsSimpleAssignment() {
+        int a = 3, b = 3, c = -2;
+        a = a * c; // Simple assignment operator
+        b *= c; // Compound assignment operator
+
+        assertEquals(a, b);
+    }
+
+    @Test
+    public void whenAssignmentOperatorIsUsed_thenValueIsReturned() {
+        long x = 1;
+        long y = (x+=2);
+
+        assertEquals(3, y);
+        assertEquals(y, x);
+    }
+
+    @Test
+    public void whenCompoundOperatorsAreUsed_thenOperationsArePerformedAndAssigned() {
+        //Simple assignment
+        int x = 5; //x is 5
+
+        //Incrementation
+        x += 5; //x is 10
+        assertEquals(10, x);
+
+        //Decrementation
+        x -= 2; //x is 8
+        assertEquals(8, x);
+
+        //Multiplication
+        x *= 2; //x is 16
+        assertEquals(16, x);
+
+        //Division
+        x /= 4; //x is 4
+        assertEquals(4, x);
+
+        //Modulus
+        x %= 3; //x is 1
+        assertEquals(1, x);
+
+
+        //Binary AND
+        x &= 4; //x is 0
+        assertEquals(0, x);
+
+        //Binary exclusive OR
+        x ^= 4; //x is 4
+        assertEquals(4, x);
+
+        //Binary inclusive OR
+        x |= 8; //x is 12
+        assertEquals(12, x);
+
+
+        //Binary Left Shift
+        x <<= 2; //x is 48
+        assertEquals(48, x);
+
+        //Binary Right Shift
+        x >>= 2; //x is 12
+        assertEquals(12, x);
+
+        //Shift right zero fill
+        x >>>= 1; //x is 6
+        assertEquals(6, x);
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void whenArrayIsNull_thenThrowNullException() {
+        int[] numbers = null;
+
+        //Trying Incrementation
+        numbers[2] += 5;
+    }
+
+    @Test(expected = ArrayIndexOutOfBoundsException.class)
+    public void whenArrayIndexNotCorrect_thenThrowArrayIndexException() {
+        int[] numbers = {0, 1};
+
+        //Trying Incrementation
+        numbers[2] += 5;
+    }
+
+    @Test
+    public void whenArrayIndexIsCorrect_thenPerformOperation() {
+        int[] numbers = {0, 1};
+
+        //Incrementation
+        numbers[1] += 5;
+        assertEquals(6, numbers[1]);
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/customexception/IncorrectFileExtensionExceptionUnitTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.customexception;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.File;
+
+import org.junit.Test;
+
+public class IncorrectFileExtensionExceptionUnitTest {
+
+    @Test
+    public void testWhenCorrectFileExtensionGiven_ReceivesNoException() throws IncorrectFileNameException {
+        assertThat(FileManager.getFirstLine("correctFileNameWithProperExtension.txt")).isEqualTo("Default First Line");
+    }
+
+    @Test(expected = IncorrectFileExtensionException.class)
+    public void testWhenCorrectFileNameExceptionThrown_ReceivesNoException() throws IncorrectFileNameException {
+        StringBuffer sBuffer = new StringBuffer();
+        sBuffer.append("src");
+        sBuffer.append(File.separator);
+        sBuffer.append("test");
+        sBuffer.append(File.separator);
+        sBuffer.append("resources");
+        sBuffer.append(File.separator);
+        sBuffer.append("correctFileNameWithoutProperExtension");
+        FileManager.getFirstLine(sBuffer.toString());
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/customexception/IncorrectFileNameExceptionUnitTest.java

@@ -0,0 +1,19 @@
+package com.baeldung.customexception;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class IncorrectFileNameExceptionUnitTest {
+
+    @Test(expected = IncorrectFileNameException.class)
+    public void testWhenIncorrectFileNameExceptionThrown_ReceivesIncorrectFileNameException() throws IncorrectFileNameException {
+        FileManager.getFirstLine("wrongFileName.txt");
+    }
+
+    @Test
+    public void testWhenCorrectFileNameExceptionThrown_ReceivesNoException() throws IncorrectFileNameException {
+        assertThat(FileManager.getFirstLine("correctFileName.txt")).isEqualTo("Default First Line");
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/dynamicproxy/DynamicProxyIntegrationTest.java

@@ -0,0 +1,57 @@
+package com.baeldung.dynamicproxy;
+
+import org.junit.Test;
+
+import java.lang.reflect.Proxy;
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
+
+public class DynamicProxyIntegrationTest {
+
+    @Test
+    public void givenDynamicProxy_thenPutWorks() {
+        Map proxyInstance = (Map) Proxy.newProxyInstance(DynamicProxyIntegrationTest.class.getClassLoader(), new Class[] { Map.class }, new DynamicInvocationHandler());
+
+        proxyInstance.put("hello", "world");
+    }
+
+    @Test
+    public void givenInlineDynamicProxy_thenGetWorksOtherMethodsDoNot() {
+        Map proxyInstance = (Map) Proxy.newProxyInstance(DynamicProxyIntegrationTest.class.getClassLoader(), new Class[] { Map.class }, (proxy, method, methodArgs) -> {
+
+            if (method.getName().equals("get")) {
+                return 42;
+            } else {
+                throw new UnsupportedOperationException("Unsupported method: " + method.getName());
+            }
+        });
+
+        int result = (int) proxyInstance.get("hello");
+
+        assertEquals(42, result);
+
+        try {
+            proxyInstance.put("hello", "world");
+            fail();
+        } catch(UnsupportedOperationException e) {
+            // expected
+        }
+    }
+
+    @Test
+    public void givenTimingDynamicProxy_thenMethodInvokationsProduceTiming() {
+        Map mapProxyInstance = (Map) Proxy.newProxyInstance(DynamicProxyIntegrationTest.class.getClassLoader(), new Class[] { Map.class }, new TimingDynamicInvocationHandler(new HashMap<>()));
+
+        mapProxyInstance.put("hello", "world");
+        assertEquals("world", mapProxyInstance.get("hello"));
+
+        CharSequence csProxyInstance = (CharSequence) Proxy.newProxyInstance(DynamicProxyIntegrationTest.class.getClassLoader(), new Class[] { CharSequence.class }, new TimingDynamicInvocationHandler("Hello World"));
+
+        assertEquals('l', csProxyInstance.charAt(2));
+        assertEquals(11, csProxyInstance.length());
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/enums/values/Element1UnitTest.java

@@ -0,0 +1,48 @@
+package com.baeldung.enums.values;
+
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ *
+ * @author chris
+ */
+public class Element1UnitTest {
+    
+    public Element1UnitTest() {
+    }
+    
+    @BeforeClass
+    public static void setUpClass() {
+    }
+    
+    @AfterClass
+    public static void tearDownClass() {
+    }
+    
+    @Before
+    public void setUp() {
+    }
+    
+    @After
+    public void tearDown() {
+    }
+
+    @Test
+    public void whenAccessingToString_thenItShouldEqualName() {
+        for (Element1 e1 : Element1.values()) {
+            assertEquals(e1.name(), e1.toString());
+        }
+    }
+    
+    @Test
+    public void whenCallingValueOf_thenReturnTheCorrectEnum() {
+        for (Element1 e1 : Element1.values()) {
+            assertSame(e1, Element1.valueOf(e1.name()));
+        }
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/enums/values/Element2UnitTest.java

@@ -0,0 +1,59 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package com.baeldung.enums.values;
+
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.junit.Assert.*;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ *
+ * @author chris
+ */
+public class Element2UnitTest {
+    private static final Logger LOGGER = LoggerFactory.getLogger(Element2UnitTest.class);
+    
+    public Element2UnitTest() {
+    }
+    
+    @BeforeClass
+    public static void setUpClass() {
+    }
+    
+    @AfterClass
+    public static void tearDownClass() {
+    }
+    
+    @Before
+    public void setUp() {
+    }
+    
+    @After
+    public void tearDown() {
+    }
+
+    @Test
+    public void whenLocatebyLabel_thenReturnCorrectValue() {
+        for (Element2 e2 : Element2.values()) {
+            assertSame(e2, Element2.valueOfLabel(e2.label));
+        }
+    }
+
+    /**
+     * Test of toString method, of class Element2.
+     */
+    @Test
+    public void whenCallingToString_thenReturnLabel() {
+        for (Element2 e2 : Element2.values()) {
+            assertEquals(e2.label, e2.toString());
+        }
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/enums/values/Element3UnitTest.java

@@ -0,0 +1,57 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package com.baeldung.enums.values;
+
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ *
+ * @author chris
+ */
+public class Element3UnitTest {
+    
+    public Element3UnitTest() {
+    }
+    
+    @BeforeClass
+    public static void setUpClass() {
+    }
+    
+    @AfterClass
+    public static void tearDownClass() {
+    }
+    
+    @Before
+    public void setUp() {
+    }
+    
+    @After
+    public void tearDown() {
+    }
+
+    @Test
+    public void whenLocatebyLabel_thenReturnCorrectValue() {
+        for (Element3 e3 : Element3.values()) {
+            assertSame(e3, Element3.valueOfLabel(e3.label));
+        }
+    }
+
+    /**
+     * Test of toString method, of class Element3.
+     */
+    @Test
+    public void whenCallingToString_thenReturnLabel() {
+        for (Element3 e3 : Element3.values()) {
+            assertEquals(e3.label, e3.toString());
+        }
+    }
+    
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/enums/values/Element4UnitTest.java

@@ -0,0 +1,71 @@
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package com.baeldung.enums.values;
+
+import org.junit.After;
+import org.junit.AfterClass;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ *
+ * @author chris
+ */
+public class Element4UnitTest {
+    
+    public Element4UnitTest() {
+    }
+    
+    @BeforeClass
+    public static void setUpClass() {
+    }
+    
+    @AfterClass
+    public static void tearDownClass() {
+    }
+    
+    @Before
+    public void setUp() {
+    }
+    
+    @After
+    public void tearDown() {
+    }
+
+    @Test
+    public void whenLocatebyLabel_thenReturnCorrectValue() {
+        for (Element4 e4 : Element4.values()) {
+            assertSame(e4, Element4.valueOfLabel(e4.label));
+        }
+    }
+
+    @Test
+    public void whenLocatebyAtmNum_thenReturnCorrectValue() {
+        for (Element4 e4 : Element4.values()) {
+            assertSame(e4, Element4.valueOfAtomicNumber(e4.atomicNumber));
+        }
+    }
+
+    @Test
+    public void whenLocatebyAtmWt_thenReturnCorrectValue() {
+        for (Element4 e4 : Element4.values()) {
+            assertSame(e4, Element4.valueOfAtomicWeight(e4.atomicWeight));
+        }
+    }
+
+    /**
+     * Test of toString method, of class Element4.
+     */
+    @Test
+    public void whenCallingToString_thenReturnLabel() {
+        for (Element4 e4 : Element4.values()) {
+            assertEquals(e4.label, e4.toString());
+        }
+    }
+    
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/exceptionhandling/ExceptionsUnitTest.java

@@ -0,0 +1,80 @@
+package com.baeldung.exceptionhandling;
+
+import org.junit.Test;
+
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.nio.file.NoSuchFileException;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+public class ExceptionsUnitTest {
+
+    Exceptions exceptions = new Exceptions();
+
+    @Test
+    public void getPlayers() {
+        assertThatThrownBy(() -> exceptions.getPlayers())
+            .isInstanceOf(NoSuchFileException.class);
+    }
+
+    @Test
+    public void loadAllPlayers() {
+        assertThatThrownBy(() -> exceptions.loadAllPlayers(""))
+            .isInstanceOf(IllegalStateException.class);
+    }
+
+    @Test
+    public void getPlayerScoreThrows() {
+        assertThatThrownBy(() -> exceptions.getPlayerScoreThrows(""))
+            .isInstanceOf(FileNotFoundException.class);
+    }
+    
+    @Test
+    public void getPlayerScoreTryCatch() {
+        assertThatThrownBy(() -> exceptions.getPlayerScoreTryCatch(""))
+            .isInstanceOf(IllegalArgumentException.class);
+    }
+    
+    @Test
+    public void getPlayerScoreFinally() {
+        assertThatThrownBy(() -> exceptions.getPlayerScoreFinally(""))
+            .isInstanceOf(FileNotFoundException.class);
+    }
+    
+    @Test
+    public void loadAllPlayersThrowingChecked() {
+        assertThatThrownBy(() -> exceptions.loadAllPlayersThrowingChecked(""))
+            .isInstanceOf(TimeoutException.class);
+    }
+    
+    @Test
+    public void loadAllPlayersThrowingUnchecked() {
+        assertThatThrownBy(() -> exceptions.loadAllPlayersThrowingUnchecked(""))
+            .isInstanceOf(IllegalArgumentException.class);
+    }
+    
+    @Test
+    public void loadAllPlayersWrapping() {
+        assertThatThrownBy(() -> exceptions.loadAllPlayersWrapping(""))
+            .isInstanceOf(IOException.class);
+    }
+    
+    @Test
+    public void loadAllPlayersRethrowing() {
+        assertThatThrownBy(() -> exceptions.loadAllPlayersRethrowing(""))
+            .isInstanceOf(PlayerLoadException.class);
+    }
+    
+    @Test
+    public void loadAllPlayersThrowable() {
+        assertThatThrownBy(() -> exceptions.loadAllPlayersThrowable(""))
+            .isInstanceOf(NullPointerException.class);
+    }
+    
+    @Test
+    public void getPlayerScoreSwallowingExceptionAntiPatternAlternative2() {
+        assertThatThrownBy(() -> exceptions.getPlayerScoreSwallowingExceptionAntiPatternAlternative2(""))
+            .isInstanceOf(PlayerScoreException.class);
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/finalize/FinalizeUnitTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.finalize;
+
+import java.io.IOException;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FinalizeUnitTest {
+    @Test
+    public void whenGC_thenFinalizerExecuted() throws IOException {
+        String firstLine = new Finalizable().readFirstLine();
+        Assert.assertEquals("baeldung.com", firstLine);
+        System.gc();
+    }
+
+    @Test
+    public void whenTryWResourcesExits_thenResourceClosed() throws IOException {
+        try (CloseableResource resource = new CloseableResource()) {
+            String firstLine = resource.readFirstLine();
+            Assert.assertEquals("baeldung.com", firstLine);
+        }
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/interfaces/InnerInterfaceUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.interfaces;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class InnerInterfaceUnitTest {
+    @Test
+    public void whenCustomerListJoined_thenReturnsJoinedNames() {
+        Customer.List customerList = new CommaSeparatedCustomers();
+        customerList.Add(new Customer("customer1"));
+        customerList.Add(new Customer("customer2"));
+        assertEquals("customer1,customer2", customerList.getCustomerNames());
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/java/enumiteration/DaysOfWeekEnum.java

@@ -0,0 +1,31 @@
+package com.baeldung.java.enumiteration;
+
+import java.util.stream.Stream;
+
+public enum DaysOfWeekEnum {
+	SUNDAY("off"), 
+	MONDAY("working"), 
+	TUESDAY("working"), 
+	WEDNESDAY("working"), 
+	THURSDAY("working"), 
+	FRIDAY("working"), 
+	SATURDAY("off");
+
+	private String typeOfDay;
+
+	DaysOfWeekEnum(String typeOfDay) {
+		this.typeOfDay = typeOfDay;
+	}
+	
+	public String getTypeOfDay() {
+		return typeOfDay;
+	}
+
+	public void setTypeOfDay(String typeOfDay) {
+		this.typeOfDay = typeOfDay;
+	}
+
+	public static Stream<DaysOfWeekEnum> stream() {
+		return Stream.of(DaysOfWeekEnum.values());
+	}
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/java/enumiteration/EnumIterationExamples.java

@@ -0,0 +1,43 @@
+package com.baeldung.java.enumiteration;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.EnumSet;
+import java.util.List;
+
+
+public class EnumIterationExamples {
+	public static void main(String[] args) {
+		System.out.println("Enum iteration using EnumSet:");
+		EnumSet.allOf(DaysOfWeekEnum.class).forEach(day -> System.out.println(day));
+
+		System.out.println("Enum iteration using Stream:");
+		DaysOfWeekEnum.stream().filter(d -> d.getTypeOfDay().equals("off")).forEach(System.out::println);
+
+		System.out.println("Enum iteration using a for loop:");
+		for (DaysOfWeekEnum day : DaysOfWeekEnum.values()) {
+			System.out.println(day);
+		}
+		
+		System.out.println("Enum iteration using Arrays.asList():");
+	        Arrays.asList(DaysOfWeekEnum.values()).forEach(day -> System.out.println(day));
+	        
+	        System.out.println("Add Enum values to ArrayList:");
+	        List<DaysOfWeekEnum> days = new ArrayList<>();
+                days.add(DaysOfWeekEnum.FRIDAY);
+                days.add(DaysOfWeekEnum.SATURDAY);
+                days.add(DaysOfWeekEnum.SUNDAY);
+                for (DaysOfWeekEnum day : days) {
+                    System.out.println(day);
+                }
+                System.out.println("Remove SATURDAY from the list:");
+                days.remove(DaysOfWeekEnum.SATURDAY); 
+                if (!days.contains(DaysOfWeekEnum.SATURDAY)) { 
+                    System.out.println("Saturday is no longer in the list"); 
+                }
+                for (DaysOfWeekEnum day : days) {
+                    System.out.println(day);
+                }
+
+	}
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/java/reflection/OperationsUnitTest.java

@@ -0,0 +1,57 @@
+package com.baeldung.java.reflection;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertThat;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+import org.junit.Test;
+
+public class OperationsUnitTest {
+
+    public OperationsUnitTest() {
+    }
+
+    @Test(expected = IllegalAccessException.class)
+    public void givenObject_whenInvokePrivateMethod_thenFail() throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
+        Method andPrivateMethod = Operations.class.getDeclaredMethod("privateAnd", boolean.class, boolean.class);
+
+        Operations operationsInstance = new Operations();
+        Boolean result = (Boolean) andPrivateMethod.invoke(operationsInstance, true, false);
+
+        assertFalse(result);
+    }
+
+    @Test
+    public void givenObject_whenInvokePrivateMethod_thenCorrect() throws Exception {
+        Method andPrivatedMethod = Operations.class.getDeclaredMethod("privateAnd", boolean.class, boolean.class);
+        andPrivatedMethod.setAccessible(true);
+
+        Operations operationsInstance = new Operations();
+        Boolean result = (Boolean) andPrivatedMethod.invoke(operationsInstance, true, false);
+
+        assertFalse(result);
+    }
+
+    @Test
+    public void givenObject_whenInvokePublicMethod_thenCorrect() throws Exception {
+        Method sumInstanceMethod = Operations.class.getMethod("publicSum", int.class, double.class);
+
+        Operations operationsInstance = new Operations();
+        Double result = (Double) sumInstanceMethod.invoke(operationsInstance, 1, 3);
+
+        assertThat(result, equalTo(4.0));
+    }
+
+    @Test
+    public void givenObject_whenInvokeStaticMethod_thenCorrect() throws Exception {
+        Method multiplyStaticMethod = Operations.class.getDeclaredMethod("publicStaticMultiply", float.class, long.class);
+
+        Double result = (Double) multiplyStaticMethod.invoke(null, 3.5f, 2);
+
+        assertThat(result, equalTo(7.0));
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/java/reflection/ReflectionUnitTest.java

@@ -0,0 +1,302 @@
+package com.baeldung.java.reflection;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Test;
+
+public class ReflectionUnitTest {
+
+    @Test
+    public void givenObject_whenGetsFieldNamesAtRuntime_thenCorrect() {
+        final Object person = new Person();
+        final Field[] fields = person.getClass().getDeclaredFields();
+
+        final List<String> actualFieldNames = getFieldNames(fields);
+
+        assertTrue(Arrays.asList("name", "age").containsAll(actualFieldNames));
+    }
+
+    @Test
+    public void givenObject_whenGetsClassName_thenCorrect() {
+        final Object goat = new Goat("goat");
+        final Class<?> clazz = goat.getClass();
+
+        assertEquals("Goat", clazz.getSimpleName());
+        assertEquals("com.baeldung.java.reflection.Goat", clazz.getName());
+        assertEquals("com.baeldung.java.reflection.Goat", clazz.getCanonicalName());
+    }
+
+    @Test
+    public void givenClassName_whenCreatesObject_thenCorrect() throws ClassNotFoundException {
+        final Class<?> clazz = Class.forName("com.baeldung.java.reflection.Goat");
+
+        assertEquals("Goat", clazz.getSimpleName());
+        assertEquals("com.baeldung.java.reflection.Goat", clazz.getName());
+        assertEquals("com.baeldung.java.reflection.Goat", clazz.getCanonicalName());
+    }
+
+    @Test
+    public void givenClass_whenRecognisesModifiers_thenCorrect() throws ClassNotFoundException {
+        final Class<?> goatClass = Class.forName("com.baeldung.java.reflection.Goat");
+        final Class<?> animalClass = Class.forName("com.baeldung.java.reflection.Animal");
+        final int goatMods = goatClass.getModifiers();
+        final int animalMods = animalClass.getModifiers();
+
+        assertTrue(Modifier.isPublic(goatMods));
+        assertTrue(Modifier.isAbstract(animalMods));
+        assertTrue(Modifier.isPublic(animalMods));
+    }
+
+    @Test
+    public void givenClass_whenGetsPackageInfo_thenCorrect() {
+        final Goat goat = new Goat("goat");
+        final Class<?> goatClass = goat.getClass();
+        final Package pkg = goatClass.getPackage();
+
+        assertEquals("com.baeldung.java.reflection", pkg.getName());
+    }
+
+    @Test
+    public void givenClass_whenGetsSuperClass_thenCorrect() {
+        final Goat goat = new Goat("goat");
+        final String str = "any string";
+
+        final Class<?> goatClass = goat.getClass();
+        final Class<?> goatSuperClass = goatClass.getSuperclass();
+
+        assertEquals("Animal", goatSuperClass.getSimpleName());
+        assertEquals("Object", str.getClass().getSuperclass().getSimpleName());
+
+    }
+
+    @Test
+    public void givenClass_whenGetsImplementedInterfaces_thenCorrect() throws ClassNotFoundException {
+        final Class<?> goatClass = Class.forName("com.baeldung.java.reflection.Goat");
+        final Class<?> animalClass = Class.forName("com.baeldung.java.reflection.Animal");
+        final Class<?>[] goatInterfaces = goatClass.getInterfaces();
+        final Class<?>[] animalInterfaces = animalClass.getInterfaces();
+
+        assertEquals(1, goatInterfaces.length);
+        assertEquals(1, animalInterfaces.length);
+        assertEquals("Locomotion", goatInterfaces[0].getSimpleName());
+        assertEquals("Eating", animalInterfaces[0].getSimpleName());
+    }
+
+    @Test
+    public void givenClass_whenGetsConstructor_thenCorrect() throws ClassNotFoundException {
+        final Class<?> goatClass = Class.forName("com.baeldung.java.reflection.Goat");
+        final Constructor<?>[] constructors = goatClass.getConstructors();
+
+        assertEquals(1, constructors.length);
+        assertEquals("com.baeldung.java.reflection.Goat", constructors[0].getName());
+    }
+
+    @Test
+    public void givenClass_whenGetsFields_thenCorrect() throws ClassNotFoundException {
+        final Class<?> animalClass = Class.forName("com.baeldung.java.reflection.Animal");
+        final Field[] fields = animalClass.getDeclaredFields();
+
+        final List<String> actualFields = getFieldNames(fields);
+
+        assertEquals(2, actualFields.size());
+        assertTrue(actualFields.containsAll(Arrays.asList("name", "CATEGORY")));
+    }
+
+    @Test
+    public void givenClass_whenGetsMethods_thenCorrect() throws ClassNotFoundException {
+        final Class<?> animalClass = Class.forName("com.baeldung.java.reflection.Animal");
+        final Method[] methods = animalClass.getDeclaredMethods();
+        final List<String> actualMethods = getMethodNames(methods);
+
+        assertEquals(3, actualMethods.size());
+        assertTrue(actualMethods.containsAll(Arrays.asList("getName", "setName", "getSound")));
+    }
+
+    @Test
+    public void givenClass_whenGetsAllConstructors_thenCorrect() throws ClassNotFoundException {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Constructor<?>[] constructors = birdClass.getConstructors();
+
+        assertEquals(3, constructors.length);
+    }
+
+    @Test
+    public void givenClass_whenGetsEachConstructorByParamTypes_thenCorrect() throws Exception {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        birdClass.getConstructor();
+        birdClass.getConstructor(String.class);
+        birdClass.getConstructor(String.class, boolean.class);
+    }
+
+    @Test
+    public void givenClass_whenInstantiatesObjectsAtRuntime_thenCorrect() throws Exception {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+
+        final Constructor<?> cons1 = birdClass.getConstructor();
+        final Constructor<?> cons2 = birdClass.getConstructor(String.class);
+        final Constructor<?> cons3 = birdClass.getConstructor(String.class, boolean.class);
+
+        final Bird bird1 = (Bird) cons1.newInstance();
+        final Bird bird2 = (Bird) cons2.newInstance("Weaver bird");
+        final Bird bird3 = (Bird) cons3.newInstance("dove", true);
+
+        assertEquals("bird", bird1.getName());
+        assertEquals("Weaver bird", bird2.getName());
+        assertEquals("dove", bird3.getName());
+        assertFalse(bird1.walks());
+        assertTrue(bird3.walks());
+    }
+
+    @Test
+    public void givenClass_whenGetsPublicFields_thenCorrect() throws ClassNotFoundException {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Field[] fields = birdClass.getFields();
+        assertEquals(1, fields.length);
+        assertEquals("CATEGORY", fields[0].getName());
+
+    }
+
+    @Test
+    public void givenClass_whenGetsPublicFieldByName_thenCorrect() throws Exception {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Field field = birdClass.getField("CATEGORY");
+        assertEquals("CATEGORY", field.getName());
+
+    }
+
+    @Test
+    public void givenClass_whenGetsDeclaredFields_thenCorrect() throws ClassNotFoundException {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Field[] fields = birdClass.getDeclaredFields();
+        assertEquals(1, fields.length);
+        assertEquals("walks", fields[0].getName());
+    }
+
+    @Test
+    public void givenClass_whenGetsFieldsByName_thenCorrect() throws Exception {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Field field = birdClass.getDeclaredField("walks");
+        assertEquals("walks", field.getName());
+
+    }
+
+    @Test
+    public void givenClassField_whenGetsType_thenCorrect() throws Exception {
+        final Field field = Class.forName("com.baeldung.java.reflection.Bird").getDeclaredField("walks");
+        final Class<?> fieldClass = field.getType();
+        assertEquals("boolean", fieldClass.getSimpleName());
+    }
+
+    @Test
+    public void givenClassField_whenSetsAndGetsValue_thenCorrect() throws Exception {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Bird bird = (Bird) birdClass.newInstance();
+        final Field field = birdClass.getDeclaredField("walks");
+        field.setAccessible(true);
+
+        assertFalse(field.getBoolean(bird));
+        assertFalse(bird.walks());
+
+        field.set(bird, true);
+
+        assertTrue(field.getBoolean(bird));
+        assertTrue(bird.walks());
+
+    }
+
+    @Test
+    public void givenClassField_whenGetsAndSetsWithNull_thenCorrect() throws Exception {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Field field = birdClass.getField("CATEGORY");
+        field.setAccessible(true);
+
+        assertEquals("domestic", field.get(null));
+    }
+
+    @Test
+    public void givenClass_whenGetsAllPublicMethods_thenCorrect() throws ClassNotFoundException {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Method[] methods = birdClass.getMethods();
+        final List<String> methodNames = getMethodNames(methods);
+
+        assertTrue(methodNames.containsAll(Arrays.asList("equals", "notifyAll", "hashCode", "walks", "eats", "toString")));
+
+    }
+
+    @Test
+    public void givenClass_whenGetsOnlyDeclaredMethods_thenCorrect() throws ClassNotFoundException {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final List<String> actualMethodNames = getMethodNames(birdClass.getDeclaredMethods());
+
+        final List<String> expectedMethodNames = Arrays.asList("setWalks", "walks", "getSound", "eats");
+
+        assertEquals(expectedMethodNames.size(), actualMethodNames.size());
+        assertTrue(expectedMethodNames.containsAll(actualMethodNames));
+        assertTrue(actualMethodNames.containsAll(expectedMethodNames));
+
+    }
+
+    @Test
+    public void givenMethodName_whenGetsMethod_thenCorrect() throws Exception {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Method walksMethod = birdClass.getDeclaredMethod("walks");
+        final Method setWalksMethod = birdClass.getDeclaredMethod("setWalks", boolean.class);
+
+        assertFalse(walksMethod.isAccessible());
+        assertFalse(setWalksMethod.isAccessible());
+
+        walksMethod.setAccessible(true);
+        setWalksMethod.setAccessible(true);
+
+        assertTrue(walksMethod.isAccessible());
+        assertTrue(setWalksMethod.isAccessible());
+
+    }
+
+    @Test
+    public void givenMethod_whenInvokes_thenCorrect() throws Exception {
+        final Class<?> birdClass = Class.forName("com.baeldung.java.reflection.Bird");
+        final Bird bird = (Bird) birdClass.newInstance();
+        final Method setWalksMethod = birdClass.getDeclaredMethod("setWalks", boolean.class);
+        final Method walksMethod = birdClass.getDeclaredMethod("walks");
+        final boolean walks = (boolean) walksMethod.invoke(bird);
+
+        assertFalse(walks);
+        assertFalse(bird.walks());
+
+        setWalksMethod.invoke(bird, true);
+        final boolean walks2 = (boolean) walksMethod.invoke(bird);
+
+        assertTrue(walks2);
+        assertTrue(bird.walks());
+
+    }
+
+    private static List<String> getFieldNames(Field[] fields) {
+        final List<String> fieldNames = new ArrayList<>();
+        for (final Field field : fields) {
+            fieldNames.add(field.getName());
+        }
+        return fieldNames;
+
+    }
+
+    private static List<String> getMethodNames(Method[] methods) {
+        final List<String> methodNames = new ArrayList<>();
+        for (final Method method : methods) {
+            methodNames.add(method.getName());
+        }
+        return methodNames;
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/nativekeyword/DateTimeUtilsManualTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.nativekeyword;
+
+import static org.junit.Assert.assertNotNull;
+
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.slf4j.Logger;
+
+public class DateTimeUtilsManualTest {
+
+    private static final Logger LOG = org.slf4j.LoggerFactory.getLogger(DateTimeUtilsManualTest.class);
+
+    @BeforeClass
+    public static void setUpClass() {
+        System.loadLibrary("msvcr100");
+        System.loadLibrary("libgcc_s_sjlj-1");
+        System.loadLibrary("libstdc++-6");
+        System.loadLibrary("nativedatetimeutils");
+    }
+
+    @Test
+    public void givenNativeLibsLoaded_thenNativeMethodIsAccessible() {
+        DateTimeUtils dateTimeUtils = new DateTimeUtils();
+        LOG.info("System time is : " + dateTimeUtils.getSystemTime());
+        assertNotNull(dateTimeUtils.getSystemTime());
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/nestedclass/AnonymousInner.java

@@ -0,0 +1,20 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+abstract class SimpleAbstractClass {
+    abstract void run();
+}
+
+public class AnonymousInner {
+
+    @Test
+    public void run() {
+        SimpleAbstractClass simpleAbstractClass = new SimpleAbstractClass() {
+            void run() {
+                System.out.println("Running Anonymous Class...");
+            }
+        };
+        simpleAbstractClass.run();
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/nestedclass/Enclosing.java

@@ -0,0 +1,21 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+public class Enclosing {
+
+    private static int x = 1;
+
+    public static class StaticNested {
+
+        private void run() {
+            System.out.println("x = " + x);
+        }
+    }
+
+    @Test
+    public void test() {
+        Enclosing.StaticNested nested = new Enclosing.StaticNested();
+        nested.run();
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/nestedclass/NewEnclosing.java

@@ -0,0 +1,22 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+public class NewEnclosing {
+
+    private void run() {
+        class Local {
+            void run() {
+                System.out.println("Welcome to Baeldung!");
+            }
+        }
+        Local local = new Local();
+        local.run();
+    }
+
+    @Test
+    public void test() {
+        NewEnclosing newEnclosing = new NewEnclosing();
+        newEnclosing.run();
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/nestedclass/NewOuter.java

@@ -0,0 +1,30 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+public class NewOuter {
+
+    int a = 1;
+    static int b = 2;
+
+    public class InnerClass {
+        int a = 3;
+        static final int b = 4;
+
+        public void run() {
+            System.out.println("a = " + a);
+            System.out.println("b = " + b);
+            System.out.println("NewOuter.this.a = " + NewOuter.this.a);
+            System.out.println("NewOuter.b = " + NewOuter.b);
+            System.out.println("NewOuter.this.b = " + NewOuter.this.b);
+        }
+    }
+
+    @Test
+    public void test() {
+        NewOuter outer = new NewOuter();
+        NewOuter.InnerClass inner = outer.new InnerClass();
+        inner.run();
+
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/nestedclass/Outer.java

@@ -0,0 +1,20 @@
+package com.baeldung.nestedclass;
+
+import org.junit.Test;
+
+public class Outer {
+
+    public class Inner {
+
+        public void run() {
+            System.out.println("Calling test...");
+        }
+    }
+
+    @Test
+    public void test() {
+        Outer outer = new Outer();
+        Outer.Inner inner = outer.new Inner();
+        inner.run();
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/noclassdeffounderror/NoClassDefFoundErrorUnitTest.java

@@ -0,0 +1,12 @@
+package com.baeldung.noclassdeffounderror;
+
+import org.junit.Test;
+
+public class NoClassDefFoundErrorUnitTest {
+
+    @Test(expected = NoClassDefFoundError.class)
+    public void givenInitErrorInClass_whenloadClass_thenNoClassDefFoundError() {
+        NoClassDefFoundErrorExample sample = new NoClassDefFoundErrorExample();
+        sample.getClassWithInitErrors();
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/objects/CarUnitTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.objects;
+
+import static org.junit.Assert.*;
+
+import org.junit.Before;
+import org.junit.Test;
+
+public class CarUnitTest {
+    
+    private Car car;
+
+    @Before
+    public void setUp() throws Exception {
+        car = new Car("Ford", "Focus", "red");
+    }
+
+    @Test
+    public final void when_speedIncreased_then_verifySpeed() {
+        car.increaseSpeed(30);
+        assertEquals(30, car.getSpeed());
+        
+        car.increaseSpeed(20);
+        assertEquals(50, car.getSpeed());
+    }
+    
+    @Test
+    public final void when_speedDecreased_then_verifySpeed() {
+        car.increaseSpeed(50);
+        assertEquals(50, car.getSpeed());
+        
+        car.decreaseSpeed(30);
+        assertEquals(20, car.getSpeed());
+        
+        car.decreaseSpeed(20);
+        assertEquals(0, car.getSpeed());
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/packages/PackagesUnitTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.packages;
+
+import static org.junit.Assert.assertEquals;
+
+import java.time.LocalDate;
+
+import org.junit.Test;
+
+import com.baeldung.packages.domain.TodoItem;
+
+public class PackagesUnitTest {
+
+    @Test
+    public void whenTodoItemAdded_ThenSizeIncreases() {
+        TodoItem todoItem = new TodoItem();
+        todoItem.setId(1L);
+        todoItem.setDescription("Test the Todo List");
+        todoItem.setDueDate(LocalDate.now());
+        TodoList todoList = new TodoList();
+        todoList.addTodoItem(todoItem);
+        assertEquals(1, todoList.getTodoItems().size());
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/recursion/RecursionExampleUnitTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.recursion;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class RecursionExampleUnitTest {
+    
+    RecursionExample recursion = new RecursionExample();
+
+    @Test
+    public void testPowerOf10() {
+        int p0 = recursion.powerOf10(0);
+        int p1 = recursion.powerOf10(1);
+        int p4 = recursion.powerOf10(4);
+        
+        Assert.assertEquals(1, p0);
+        Assert.assertEquals(10, p1);
+        Assert.assertEquals(10000, p4);
+    }
+    
+    @Test
+    public void testFibonacci() {
+        int n0 = recursion.fibonacci(0);
+        int n1 = recursion.fibonacci(1);
+        int n7 = recursion.fibonacci(7);
+        
+        Assert.assertEquals(0, n0);
+        Assert.assertEquals(1, n1);
+        Assert.assertEquals(13, n7);
+    }
+    
+    @Test
+    public void testToBinary() {
+        String b0 = recursion.toBinary(0);
+        String b1 = recursion.toBinary(1);
+        String b10 = recursion.toBinary(10);
+        
+        Assert.assertEquals("0", b0);
+        Assert.assertEquals("1", b1);
+        Assert.assertEquals("1010", b10);
+    }
+    
+    @Test
+    public void testCalculateTreeHeight() {
+        BinaryNode root = new BinaryNode(1);
+        root.setLeft(new BinaryNode(1));
+        root.setRight(new BinaryNode(1));
+        
+        root.getLeft().setLeft(new BinaryNode(1));
+        root.getLeft().getLeft().setRight(new BinaryNode(1));
+        root.getLeft().getLeft().getRight().setLeft(new BinaryNode(1));
+        
+        root.getRight().setLeft(new BinaryNode(1));
+        root.getRight().getLeft().setRight(new BinaryNode(1));
+        
+        int height = recursion.calculateTreeHeight(root);
+        
+        Assert.assertEquals(4, height);
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/sneakythrows/SneakyRunnableUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.sneakythrows;
+
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class SneakyRunnableUnitTest {
+
+    @Test
+    public void whenCallSneakyRunnableMethod_thenThrowException() {
+        try {
+            new SneakyRunnable().run();
+        } catch (Exception e) {
+            assertEquals(InterruptedException.class, e.getStackTrace());
+        }
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/sneakythrows/SneakyThrowsUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.sneakythrows;
+
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class SneakyThrowsUnitTest {
+
+    @Test
+    public void whenCallSneakyMethod_thenThrowSneakyException() {
+        try {
+            SneakyThrows.throwsSneakyIOException();
+        } catch (Exception ex) {
+            assertEquals("sneaky", ex.getMessage().toString());
+        }
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/stackoverflowerror/AccountHolderManualTest.java

@@ -0,0 +1,10 @@
+package com.baeldung.stackoverflowerror;
+
+import org.junit.Test;
+
+public class AccountHolderManualTest {
+    @Test(expected = StackOverflowError.class)
+    public void whenInstanciatingAccountHolder_thenThrowsException() {
+        AccountHolder holder = new AccountHolder();
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/stackoverflowerror/CyclicDependancyManualTest.java

@@ -0,0 +1,10 @@
+package com.baeldung.stackoverflowerror;
+
+import org.junit.Test;
+
+public class CyclicDependancyManualTest {
+    @Test(expected = StackOverflowError.class)
+    public void whenInstanciatingClassOne_thenThrowsException() {
+        ClassOne obj = new ClassOne();
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/stackoverflowerror/InfiniteRecursionWithTerminationConditionManualTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.stackoverflowerror;
+
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class InfiniteRecursionWithTerminationConditionManualTest {
+    @Test
+    public void givenPositiveIntNoOne_whenCalcFact_thenCorrectlyCalc() {
+        int numToCalcFactorial = 1;
+        InfiniteRecursionWithTerminationCondition irtc = new InfiniteRecursionWithTerminationCondition();
+
+        assertEquals(1, irtc.calculateFactorial(numToCalcFactorial));
+    }
+
+    @Test
+    public void givenPositiveIntGtOne_whenCalcFact_thenCorrectlyCalc() {
+        int numToCalcFactorial = 5;
+        InfiniteRecursionWithTerminationCondition irtc = new InfiniteRecursionWithTerminationCondition();
+
+        assertEquals(120, irtc.calculateFactorial(numToCalcFactorial));
+    }
+
+    @Test(expected = StackOverflowError.class)
+    public void givenNegativeInt_whenCalcFact_thenThrowsException() {
+        int numToCalcFactorial = -1;
+        InfiniteRecursionWithTerminationCondition irtc = new InfiniteRecursionWithTerminationCondition();
+
+        irtc.calculateFactorial(numToCalcFactorial);
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/stackoverflowerror/RecursionWithCorrectTerminationConditionManualTest.java

@@ -0,0 +1,15 @@
+package com.baeldung.stackoverflowerror;
+
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class RecursionWithCorrectTerminationConditionManualTest {
+    @Test
+    public void givenNegativeInt_whenCalcFact_thenCorrectlyCalc() {
+        int numToCalcFactorial = -1;
+        RecursionWithCorrectTerminationCondition rctc = new RecursionWithCorrectTerminationCondition();
+
+        assertEquals(1, rctc.calculateFactorial(numToCalcFactorial));
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/stackoverflowerror/UnintendedInfiniteRecursionManualTest.java

@@ -0,0 +1,30 @@
+package com.baeldung.stackoverflowerror;
+
+
+import org.junit.Test;
+
+public class UnintendedInfiniteRecursionManualTest {
+    @Test(expected = StackOverflowError.class)
+    public void givenPositiveIntNoOne_whenCalFact_thenThrowsException() {
+        int numToCalcFactorial = 1;
+        UnintendedInfiniteRecursion uir = new UnintendedInfiniteRecursion();
+
+        uir.calculateFactorial(numToCalcFactorial);
+    }
+
+    @Test(expected = StackOverflowError.class)
+    public void givenPositiveIntGtOne_whenCalcFact_thenThrowsException() {
+        int numToCalcFactorial = 2;
+        UnintendedInfiniteRecursion uir = new UnintendedInfiniteRecursion();
+
+        uir.calculateFactorial(numToCalcFactorial);
+    }
+
+    @Test(expected = StackOverflowError.class)
+    public void givenNegativeInt_whenCalcFact_thenThrowsException() {
+        int numToCalcFactorial = -1;
+        UnintendedInfiniteRecursion uir = new UnintendedInfiniteRecursion();
+
+        uir.calculateFactorial(numToCalcFactorial);
+    }
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/synthetic/SyntheticUnitTest.java

@@ -0,0 +1,99 @@
+package com.baeldung.synthetic;
+
+import java.lang.reflect.Constructor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Unit test for {@link SyntheticFieldDemo}, {@link SyntheticMethodDemo},
+ * {@link SyntheticConstructorDemo} and {@link BridgeMethodDemo} classes.
+ * 
+ * @author Donato Rimenti
+ *
+ */
+public class SyntheticUnitTest {
+
+    /**
+     * Tests that the {@link SyntheticMethodDemo.NestedClass} contains two synthetic
+     * methods.
+     */
+    @Test
+    public void givenSyntheticMethod_whenIsSinthetic_thenTrue() {
+        // Checks that the nested class contains exactly two synthetic methods.
+        Method[] methods = SyntheticMethodDemo.NestedClass.class.getDeclaredMethods();
+        Assert.assertEquals("This class should contain only two methods", 2, methods.length);
+
+        for (Method m : methods) {
+            System.out.println("Method: " + m.getName() + ", isSynthetic: " + m.isSynthetic());
+            Assert.assertTrue("All the methods of this class should be synthetic", m.isSynthetic());
+        }
+    }
+
+    /**
+     * Tests that {@link SyntheticConstructorDemo.NestedClass} contains a synthetic
+     * constructor.
+     */
+    @Test
+    public void givenSyntheticConstructor_whenIsSinthetic_thenTrue() {
+        // Checks that the nested class contains exactly a synthetic
+        // constructor.
+        int syntheticConstructors = 0;
+        Constructor<?>[] constructors = SyntheticConstructorDemo.NestedClass.class.getDeclaredConstructors();
+        Assert.assertEquals("This class should contain only two constructors", 2, constructors.length);
+
+        for (Constructor<?> c : constructors) {
+            System.out.println("Constructor: " + c.getName() + ", isSynthetic: " + c.isSynthetic());
+
+            // Counts the synthetic constructors.
+            if (c.isSynthetic()) {
+                syntheticConstructors++;
+            }
+        }
+
+        // Checks that there's exactly one synthetic constructor.
+        Assert.assertEquals(1, syntheticConstructors);
+    }
+
+    /**
+     * Tests that {@link SyntheticFieldDemo.NestedClass} contains a synthetic field.
+     */
+    @Test
+    public void givenSyntheticField_whenIsSinthetic_thenTrue() {
+        // This class should contain exactly one synthetic field.
+        Field[] fields = SyntheticFieldDemo.NestedClass.class.getDeclaredFields();
+        Assert.assertEquals("This class should contain only one field", 1, fields.length);
+
+        for (Field f : fields) {
+            System.out.println("Field: " + f.getName() + ", isSynthetic: " + f.isSynthetic());
+            Assert.assertTrue("All the fields of this class should be synthetic", f.isSynthetic());
+        }
+    }
+
+    /**
+     * Tests that {@link BridgeMethodDemo} contains a synthetic bridge method.
+     */
+    @Test
+    public void givenBridgeMethod_whenIsBridge_thenTrue() {
+        // This class should contain exactly one synthetic bridge method.
+        int syntheticMethods = 0;
+        Method[] methods = BridgeMethodDemo.class.getDeclaredMethods();
+        for (Method m : methods) {
+            System.out.println(
+                    "Method: " + m.getName() + ", isSynthetic: " + m.isSynthetic() + ", isBridge: " + m.isBridge());
+
+            // Counts the synthetic methods and checks that they are also bridge
+            // methods.
+            if (m.isSynthetic()) {
+                syntheticMethods++;
+                Assert.assertTrue("The synthetic method in this class should also be a bridge method", m.isBridge());
+            }
+        }
+        
+        // Checks that there's exactly one synthetic bridge method.
+        Assert.assertEquals("There should be exactly 1 synthetic bridge method in this class", 1, syntheticMethods);
+    }
+
+}

core-java-modules/core-java-lang/src/test/java/com/baeldung/throwsexception/SimpleServiceUnitTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.throwsexception;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+public class SimpleServiceUnitTest {
+
+    SimpleService simpleService = new SimpleService();
+
+    @Test
+    void whenSQLExceptionIsThrown_thenShouldBeRethrownWithWrappedException() {
+        assertThrows(DataAccessException.class,
+                () -> simpleService.wrappingException());
+    }
+
+    @Test
+    void whenCalled_thenNullPointerExceptionIsThrown() {
+        assertThrows(NullPointerException.class,
+                () -> simpleService.runtimeNullPointerException());
+    }
+}