Method Overloading and Overriding in Java - BAEL-1507 (#3621)

* Initial Commit

* Update Multiplier.java

* Refactored MethodOverridingUnitTest class

* Update Car.java

* Update Vehicle.java

* Update MethodOverridingUnitTest.java

* Update MethodOverridingUnitTest.java

* Fix package names

core-java/src/test/java/com/baeldung/methodoverloadingoverriding/test/MethodOverloadingUnitTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.methodoverloadingoverriding.test;
+
+import com.baeldung.methodoverloadingoverriding.util.Multiplier;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class MethodOverloadingUnitTest {
+    
+    private static Multiplier multiplier;
+    
+    @BeforeClass
+    public static void setUpMultiplierInstance() {
+        multiplier = new Multiplier();
+    }
+ 
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithTwoIntegers_thenOneAssertion() {
+        assertThat(multiplier.multiply(10, 10)).isEqualTo(100);
+    }
+    
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithTreeIntegers_thenOneAssertion() {
+        assertThat(multiplier.multiply(10, 10, 10)).isEqualTo(1000);
+    }
+    
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithIntDouble_thenOneAssertion() {
+        assertThat(multiplier.multiply(10, 10.5)).isEqualTo(105.0);
+    }
+    
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithDoubleDouble_thenOneAssertion() {
+        assertThat(multiplier.multiply(10.5, 10.5)).isEqualTo(110.25);
+    }
+    
+    @Test
+    public void givenMultiplierInstance_whenCalledMultiplyWithIntIntAndMatching_thenNoTypePromotion() {
+        assertThat(multiplier.multiply(10, 10)).isEqualTo(100);
+    }
+}

core-java/src/test/java/com/baeldung/methodoverloadingoverriding/test/MethodOverridingUnitTest.java

@@ -0,0 +1,68 @@
+package com.baeldung.methodoverloadingoverriding.test;
+
+import com.baeldung.methodoverloadingoverriding.model.Car;
+import com.baeldung.methodoverloadingoverriding.model.Vehicle;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class MethodOverridingUnitTest {
+    
+    private static Vehicle vehicle;
+    private static Car car;
+    
+    @BeforeClass
+    public static void setUpVehicleInstance() {
+        vehicle = new Vehicle();
+    }
+    
+    @BeforeClass
+    public static void setUpCarInstance() {
+        car = new Car();
+    }
+    
+    @Test
+    public void givenVehicleInstance_whenCalledAccelerate_thenOneAssertion() {
+        assertThat(vehicle.accelerate(100)).isEqualTo("The vehicle accelerates at : 100 MPH.");
+    }
+    
+    @Test
+    public void givenVehicleInstance_whenCalledRun_thenOneAssertion() {
+        assertThat(vehicle.run()).isEqualTo("The vehicle is running.");
+    }
+    
+    @Test
+    public void givenVehicleInstance_whenCalledStop_thenOneAssertion() {
+        assertThat(vehicle.stop()).isEqualTo("The vehicle has stopped.");
+    }
+    
+    @Test
+    public void givenCarInstance_whenCalledAccelerate_thenOneAssertion() {
+        assertThat(car.accelerate(80)).isEqualTo("The car accelerates at : 80 MPH.");
+    }
+    
+    @Test
+    public void givenCarInstance_whenCalledRun_thenOneAssertion() {
+        assertThat(car.run()).isEqualTo("The vehicle is running.");
+    }
+    
+    @Test
+    public void givenCarInstance_whenCalledStop_thenOneAssertion() {
+        assertThat(car.stop()).isEqualTo("The vehicle has stopped.");
+    }
+    
+    @Test
+    public void givenVehicleCarInstances_whenCalledAccelerateWithSameArgument_thenNotEqual() {
+        assertThat(vehicle.accelerate(100)).isNotEqualTo(car.accelerate(100));
+    }
+    
+    @Test
+    public void givenVehicleCarInstances_whenCalledRun_thenEqual() {
+        assertThat(vehicle.run()).isEqualTo(car.run());
+    }
+    
+    @Test
+    public void givenVehicleCarInstances_whenCalledStop_thenEqual() {
+        assertThat(vehicle.stop()).isEqualTo(car.stop());
+    }
+}