diff --git a/processor/src/test/java/org/javahelpers/simple/builders/processor/SealedTypesTest.java b/processor/src/test/java/org/javahelpers/simple/builders/processor/SealedTypesTest.java
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+++ b/processor/src/test/java/org/javahelpers/simple/builders/processor/SealedTypesTest.java
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+/*
+ * MIT License
+ *
+ * Copyright (c) 2025 Andreas Igel
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package org.javahelpers.simple.builders.processor;
+
+import static com.google.testing.compile.CompilationSubject.assertThat;
+import static org.javahelpers.simple.builders.processor.testing.ProcessorTestUtils.loadGeneratedSource;
+
+import com.google.testing.compile.Compilation;
+import javax.tools.JavaFileObject;
+import org.javahelpers.simple.builders.processor.testing.ProcessorAsserts;
+import org.javahelpers.simple.builders.processor.testing.ProcessorTestUtils;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests for sealed types support (Java 17+).
+ *
+ * Verifies that builders are generated correctly for classes that:
+ *
+ *
+ * - Implement sealed interfaces
+ *
- Extend sealed abstract classes
+ *
- Are part of sealed type hierarchies with multiple implementations
+ *
+ *
+ * @see Issue #95
+ */
+class SealedTypesTest {
+
+ private static Compilation compile(JavaFileObject... sources) {
+ return ProcessorTestUtils.createCompiler().compile(sources);
+ }
+
+ @Test
+ void classImplementingSealedInterface_builderGenerated() {
+ JavaFileObject sealedInterface =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ public sealed interface Vehicle permits Car, Truck {
+ String getType();
+ }
+ """);
+
+ JavaFileObject carClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ @org.javahelpers.simple.builders.core.annotations.SimpleBuilder
+ public final class Car implements Vehicle {
+ private final String brand;
+ private final int year;
+
+ public Car(String brand, int year) {
+ this.brand = brand;
+ this.year = year;
+ }
+
+ public String getBrand() { return brand; }
+ public int getYear() { return year; }
+
+ @Override
+ public String getType() { return "Car"; }
+ }
+ """);
+
+ JavaFileObject truckClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ public final class Truck implements Vehicle {
+ private final int capacity;
+
+ public Truck(int capacity) {
+ this.capacity = capacity;
+ }
+
+ public int getCapacity() { return capacity; }
+
+ @Override
+ public String getType() { return "Truck"; }
+ }
+ """);
+
+ Compilation compilation = compile(sealedInterface, carClass, truckClass);
+ assertThat(compilation).succeeded();
+
+ String generatedCode = loadGeneratedSource(compilation, "CarBuilder");
+
+ ProcessorAsserts.assertContaining(
+ generatedCode,
+ "public class CarBuilder",
+ "public CarBuilder brand(String brand)",
+ "public CarBuilder year(int year)",
+ "public Car build()");
+ }
+
+ @Test
+ void classExtendingSealedAbstractClass_builderGenerated() {
+ JavaFileObject sealedAbstractClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ public sealed abstract class Animal permits Dog, Cat {
+ private final String name;
+
+ protected Animal(String name) {
+ this.name = name;
+ }
+
+ public String getName() { return name; }
+ public abstract String makeSound();
+ }
+ """);
+
+ JavaFileObject dogClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ @org.javahelpers.simple.builders.core.annotations.SimpleBuilder
+ public final class Dog extends Animal {
+ private final String breed;
+
+ public Dog(String name, String breed) {
+ super(name);
+ this.breed = breed;
+ }
+
+ public String getBreed() { return breed; }
+
+ @Override
+ public String makeSound() { return "Woof"; }
+ }
+ """);
+
+ JavaFileObject catClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ public final class Cat extends Animal {
+ public Cat(String name) {
+ super(name);
+ }
+
+ @Override
+ public String makeSound() { return "Meow"; }
+ }
+ """);
+
+ Compilation compilation = compile(sealedAbstractClass, dogClass, catClass);
+ assertThat(compilation).succeeded();
+
+ String generatedCode = loadGeneratedSource(compilation, "DogBuilder");
+
+ ProcessorAsserts.assertContaining(
+ generatedCode,
+ "public class DogBuilder",
+ "public DogBuilder name(String name)",
+ "public DogBuilder breed(String breed)",
+ "public Dog build()");
+ }
+
+ @Test
+ void multipleImplementationsInSealedHierarchy_allBuildersGenerated() {
+ JavaFileObject sealedInterface =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ public sealed interface Shape permits Circle, Rectangle {
+ double area();
+ }
+ """);
+
+ JavaFileObject circleClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ @org.javahelpers.simple.builders.core.annotations.SimpleBuilder
+ public final class Circle implements Shape {
+ private final double radius;
+
+ public Circle(double radius) {
+ this.radius = radius;
+ }
+
+ public double getRadius() { return radius; }
+
+ @Override
+ public double area() { return Math.PI * radius * radius; }
+ }
+ """);
+
+ JavaFileObject rectangleClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ @org.javahelpers.simple.builders.core.annotations.SimpleBuilder
+ public final class Rectangle implements Shape {
+ private final double width;
+ private final double height;
+
+ public Rectangle(double width, double height) {
+ this.width = width;
+ this.height = height;
+ }
+
+ public double getWidth() { return width; }
+ public double getHeight() { return height; }
+
+ @Override
+ public double area() { return width * height; }
+ }
+ """);
+
+ Compilation compilation = compile(sealedInterface, circleClass, rectangleClass);
+ assertThat(compilation).succeeded();
+
+ String circleBuilder = loadGeneratedSource(compilation, "CircleBuilder");
+ ProcessorAsserts.assertContaining(
+ circleBuilder,
+ "public class CircleBuilder",
+ "public CircleBuilder radius(double radius)",
+ "public Circle build()");
+
+ String rectangleBuilder = loadGeneratedSource(compilation, "RectangleBuilder");
+ ProcessorAsserts.assertContaining(
+ rectangleBuilder,
+ "public class RectangleBuilder",
+ "public RectangleBuilder width(double width)",
+ "public RectangleBuilder height(double height)",
+ "public Rectangle build()");
+ }
+
+ @Test
+ void sealedInterfaceWithComplexHierarchy_builderGenerated() {
+ JavaFileObject sealedInterface =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ public sealed interface Payment permits CreditCardPayment, CashPayment {
+ double getAmount();
+ }
+ """);
+
+ JavaFileObject creditCardClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ @org.javahelpers.simple.builders.core.annotations.SimpleBuilder
+ public final class CreditCardPayment implements Payment {
+ private final double amount;
+ private final String cardNumber;
+ private final String cvv;
+
+ public CreditCardPayment(double amount, String cardNumber, String cvv) {
+ this.amount = amount;
+ this.cardNumber = cardNumber;
+ this.cvv = cvv;
+ }
+
+ @Override
+ public double getAmount() { return amount; }
+ public String getCardNumber() { return cardNumber; }
+ public String getCvv() { return cvv; }
+ }
+ """);
+
+ JavaFileObject cashClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ @org.javahelpers.simple.builders.core.annotations.SimpleBuilder
+ public final class CashPayment implements Payment {
+ private final double amount;
+ private final String currency;
+
+ public CashPayment(double amount, String currency) {
+ this.amount = amount;
+ this.currency = currency;
+ }
+
+ @Override
+ public double getAmount() { return amount; }
+ public String getCurrency() { return currency; }
+ }
+ """);
+
+ Compilation compilation = compile(sealedInterface, creditCardClass, cashClass);
+ assertThat(compilation).succeeded();
+
+ String creditCardBuilder = loadGeneratedSource(compilation, "CreditCardPaymentBuilder");
+ ProcessorAsserts.assertContaining(
+ creditCardBuilder,
+ "public class CreditCardPaymentBuilder",
+ "public CreditCardPaymentBuilder amount(double amount)",
+ "public CreditCardPaymentBuilder cardNumber(String cardNumber)",
+ "public CreditCardPaymentBuilder cvv(String cvv)",
+ "public CreditCardPayment build()");
+
+ String cashBuilder = loadGeneratedSource(compilation, "CashPaymentBuilder");
+ ProcessorAsserts.assertContaining(
+ cashBuilder,
+ "public class CashPaymentBuilder",
+ "public CashPaymentBuilder amount(double amount)",
+ "public CashPaymentBuilder currency(String currency)",
+ "public CashPayment build()");
+ }
+
+ @Test
+ void nonSealedSubclassOfSealedClass_builderGenerated() {
+ JavaFileObject sealedClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ public sealed abstract class BaseEntity permits ConcreteEntity {
+ private final long id;
+
+ protected BaseEntity(long id) {
+ this.id = id;
+ }
+
+ public long getId() { return id; }
+ }
+ """);
+
+ JavaFileObject concreteClass =
+ ProcessorTestUtils.forSource(
+ """
+ package test;
+ @org.javahelpers.simple.builders.core.annotations.SimpleBuilder
+ public non-sealed class ConcreteEntity extends BaseEntity {
+ private final String data;
+
+ public ConcreteEntity(long id, String data) {
+ super(id);
+ this.data = data;
+ }
+
+ public String getData() { return data; }
+ }
+ """);
+
+ Compilation compilation = compile(sealedClass, concreteClass);
+ assertThat(compilation).succeeded();
+
+ String generatedCode = loadGeneratedSource(compilation, "ConcreteEntityBuilder");
+
+ ProcessorAsserts.assertContaining(
+ generatedCode,
+ "public class ConcreteEntityBuilder",
+ "public ConcreteEntityBuilder id(long id)",
+ "public ConcreteEntityBuilder data(String data)",
+ "public ConcreteEntity build()");
+ }
+}