BAEL-5138: Implementation code for Lombok @With Methods (#11494)

* BAEL-5138: Implementation code for Lombok @With Methods

* BAEL-5138: Implementation code for Lombok @With Methods

 * Fixed a type issue in HolderUnitTest
 * Removed a constructor from User to avoid confusion with article

lombok/src/main/java/com/baeldung/lombok/with/Device.java

@@ -0,0 +1,13 @@
+package com.baeldung.lombok.with;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.With;
+
+@Getter
+@AllArgsConstructor
+public abstract class Device {
+    private final String serial;
+    @With
+    private final boolean isInspected;
+}

lombok/src/main/java/com/baeldung/lombok/with/Holder.java

@@ -0,0 +1,16 @@
+package com.baeldung.lombok.with;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.With;
+
+@Getter
+@AllArgsConstructor
+public class Holder {
+    @With
+    private String variableA;
+    @With
+    private String _variableB;
+    @With
+    private String $variableC;
+}

lombok/src/main/java/com/baeldung/lombok/with/ImprovedUser.java

@@ -0,0 +1,14 @@
+package com.baeldung.lombok.with;
+
+import lombok.AllArgsConstructor;
+import lombok.NonNull;
+import lombok.With;
+
+@With
+@AllArgsConstructor
+public class ImprovedUser {
+    @NonNull
+    private final String username;
+    @NonNull
+    private final String emailAddress;
+}

lombok/src/main/java/com/baeldung/lombok/with/KioskDevice.java

@@ -0,0 +1,13 @@
+package com.baeldung.lombok.with;
+
+public class KioskDevice extends Device {
+
+    public KioskDevice(String serial, boolean isInspected) {
+        super(serial, isInspected);
+    }
+
+    @Override
+    public Device withInspected(boolean isInspected) {
+        return new KioskDevice(getSerial(), isInspected);
+    }
+}

lombok/src/main/java/com/baeldung/lombok/with/Stock.java

@@ -0,0 +1,23 @@
+package com.baeldung.lombok.with;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.With;
+
+@Getter
+@AllArgsConstructor
+public class Stock {
+    @With
+    private String sku;
+    private int stockCount;
+
+    public Stock withSku(String sku) {
+        return new Stock("mod-" + sku, stockCount);
+    }
+
+    public Stock withSKU(String... sku) {
+        return sku == null || sku.length == 0 ?
+            new Stock("unknown", stockCount) :
+            new Stock("mod-" + sku[0], stockCount);
+    }
+}

lombok/src/main/java/com/baeldung/lombok/with/User.java

@@ -0,0 +1,14 @@
+package com.baeldung.lombok.with;
+
+import lombok.AllArgsConstructor;
+import lombok.Getter;
+import lombok.With;
+
+@Getter
+@AllArgsConstructor
+public class User {
+    private final String username;
+    private final String emailAddress;
+    @With
+    private final boolean isAuthenticated;
+}

lombok/src/test/java/com/baeldung/lombok/with/HolderUnitTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.lombok.with;
+
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+
+public class HolderUnitTest {
+
+    @Test
+    public void whenWithMethodsGenerated_thenUsable() {
+        Holder value = new Holder("a", "b");
+
+        Holder valueModifiedA = value.withVariableA("mod-a");
+        Holder valueModifiedB = value.with_variableB("mod-b");
+        // Holder valueModifiedC = value.with$VariableC("mod-c"); not possible
+
+        assertNotSame(valueModifiedA, value);
+        assertNotSame(valueModifiedB, value);
+        assertEquals("mod-a", valueModifiedA.getVariableA());
+        assertEquals("mod-b", valueModifiedB.get_variableB());
+    }
+}

lombok/src/test/java/com/baeldung/lombok/with/ImprovedUserUnitTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.lombok.with;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class ImprovedUserUnitTest {
+
+    @Test
+    public void whenUsernameNull_thenException() {
+        ImprovedUser user = new ImprovedUser("testuser", "test@mail.com");
+
+        assertThrows(NullPointerException.class, () -> user.withUsername(null));
+    }
+
+    @Test
+    public void whenEmailNull_thenException() {
+        ImprovedUser user = new ImprovedUser("testuser", "test@mail.com");
+
+        assertThrows(NullPointerException.class, () -> user.withEmailAddress(null));
+    }
+}

lombok/src/test/java/com/baeldung/lombok/with/KioskDeviceWithUnitTest.java

@@ -0,0 +1,21 @@
+package com.baeldung.lombok.with;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class KioskDeviceWithUnitTest {
+
+    @Test
+    public void whenDeviceInspected_thenClonedAndUpdated() {
+        KioskDevice device = new KioskDevice("S-001", false);
+
+        Device inspectedDevice = device.withInspected(true);
+
+        assertNotSame(inspectedDevice, device);
+        assertFalse(device.isInspected());
+        assertTrue(inspectedDevice.isInspected());
+    }
+}

lombok/src/test/java/com/baeldung/lombok/with/StockWithUnitTest.java

@@ -0,0 +1,22 @@
+package com.baeldung.lombok.with;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class StockWithUnitTest {
+
+    @Test
+    public void givenWithManuallyProvided_whenSkuChanged_thenManualMethodUsed() {
+        Stock stock = new Stock("sku-001", 5);
+
+        Stock modifiedStock = stock.withSku("sku-002");
+        Stock anotherModifiedStock = stock.withSKU("sku-003", "sku-004");
+
+        assertNotSame(modifiedStock, stock);
+        assertNotSame(anotherModifiedStock, stock);
+        assertTrue(modifiedStock.getSku().startsWith("mod"));
+        assertTrue(anotherModifiedStock.getSku().startsWith("mod"));
+    }
+}

lombok/src/test/java/com/baeldung/lombok/with/UserWithUnitTest.java

@@ -0,0 +1,21 @@
+package com.baeldung.lombok.with;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class UserWithUnitTest {
+
+    @Test
+    public void whenUserAuthenticated_thenClonedAndUpdated() {
+        User immutableUser = new User("testuser", "test@mail.com", false);
+
+        User authenticatedUser = immutableUser.withAuthenticated(true);
+
+        assertNotSame(immutableUser, authenticatedUser);
+        assertFalse(immutableUser.isAuthenticated());
+        assertTrue(authenticatedUser.isAuthenticated());
+    }
+}