JavaBeanTester.java

/*
 * SPDX-License-Identifier: Apache-2.0
 * See LICENSE file for details.
 *
 * Copyright 2012-2026 hazendaz
 *
 * Portions of initial baseline code (getter/setter test) by Rob Dawson (CodeBox)
 */
package com.codebox.bean;

import com.codebox.util.LombokBuilderUtil;

import java.lang.reflect.Modifier;

import net.bytebuddy.ByteBuddy;
import net.bytebuddy.NamingStrategy;
import net.bytebuddy.description.NamedElement;
import net.bytebuddy.description.modifier.Visibility;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
import net.bytebuddy.implementation.HashCodeMethod;
import net.bytebuddy.implementation.MethodDelegation;
import net.bytebuddy.implementation.ToStringMethod;
import net.bytebuddy.implementation.bind.annotation.Argument;
import net.bytebuddy.implementation.bind.annotation.This;
import net.bytebuddy.matcher.ElementMatchers;

/**
 * Entry point for configuring tests of JavaBean-style value objects.
 *
 * <p>
 * Start with one of the {@code builder(...)} factory methods, enable any optional checks, and finish with a terminal
 * method on {@link JavaBeanTesterBuilder}.
 *
 * <pre>
 * JavaBeanTester.builder(SampleBean.class).checkEquals().loadData().test();
 * </pre>
 */
public enum JavaBeanTester {

    // Private Usage
    ;

    /**
     * Creates a builder for the supplied class using the default extension strategy.
     *
     * <p>
     * This overload is the preferred entry point. Final classes fall back to {@link Object} for extension comparisons,
     * Lombok builder classes skip generated extensions, and other classes receive a generated Byte Buddy extension when
     * equality-related checks need one.
     *
     * @param <T>
     *            the type under test
     * @param clazz
     *            the class under test
     *
     * @return a builder for configuring and running bean tests
     */
    public static <T> JavaBeanTesterBuilder<T, ?> builder(final Class<T> clazz) {
        // If class is final, use Object.class for comparison needs
        if (Modifier.isFinal(clazz.getModifiers())) {
            return new JavaBeanTesterBuilder<>(clazz, Object.class);
        }

        // Lombok builder not supported by byte buddy, do not attempt to build extension class
        if (LombokBuilderUtil.getLombokBuilderMethod(clazz) != null) {
            return builder(clazz, null);
        }

        // Build extension from class using byte buddy
        Class<? extends T> loaded = new ByteBuddy().with(new NamingStrategy.AbstractBase() {
            @Override
            protected String name(TypeDescription superClass) {
                return clazz.getPackageName() + ".ByteBuddyExt" + superClass.getSimpleName();
            }
        }).subclass(clazz).method(ElementMatchers.isEquals())
                .intercept(MethodDelegation.to(InstanceOfEqualsInterceptor.class)).method(ElementMatchers.isHashCode())
                .intercept(HashCodeMethod.usingSuperClassOffset()).method(ElementMatchers.isToString())
                .intercept(ToStringMethod.prefixedBySimpleClassName()).method(ElementMatchers.named("canEqual"))
                .intercept(MethodDelegation.to(CanEqualInterceptor.class))
                .defineField("javabeanExtension", String.class, Visibility.PACKAGE_PRIVATE).make()
                .load(clazz.getClassLoader(), ClassLoadingStrategy.Default.WRAPPER).getLoaded();

        // Builder with proper extension class
        return builder(clazz, loaded);
    }

    /**
     * Creates a builder with an explicitly supplied extension type.
     *
     * <p>
     * Pass {@code null} to disable extension generation entirely, or provide a custom extension type when equality
     * verification should use a known subclass instead of the generated one.
     *
     * @param <T>
     *            the type under test
     * @param <E>
     *            the extension type used for equality-related checks
     * @param clazz
     *            the class under test
     * @param extension
     *            the extension type to use, or {@code null} to disable extension generation
     *
     * @return a builder for configuring and running bean tests
     */
    public static <T, E> JavaBeanTesterBuilder<T, E> builder(final Class<T> clazz, final Class<E> extension) {
        return new JavaBeanTesterBuilder<>(clazz, extension);
    }

    /**
     * The Class CanEqualInterceptor.
     */
    public static final class CanEqualInterceptor {

        /**
         * Prevents instantiation a new can equal interceptor.
         */
        CanEqualInterceptor() {
            // Private constructor to prevent instantiation
        }

        /**
         * Can Equal Interceptor.
         *
         * @param object
         *            The object to check can equals
         * @return boolean of can equals
         */
        public static boolean canEqual(final Object object) {
            return object instanceof NamedElement.WithRuntimeName;
        }

    }

    /**
     * The Class InstanceOfEqualsInterceptor.
     */
    public static final class InstanceOfEqualsInterceptor {

        /**
         * Prevents instantiation a new instance of equals interceptor.
         */
        InstanceOfEqualsInterceptor() {
            // Private constructor to prevent instantiation
        }

        /**
         * Equals.
         *
         * @param self
         *            the self
         * @param other
         *            the other
         * @return true, if successful
         */
        public static boolean equals(@This Object self, @Argument(0) Object other) {
            if (self == other) {
                return true;
            }
            if ((other == null) || (!self.getClass().isInstance(other) && !other.getClass().isInstance(self))) {
                return false;
            }
            return self.hashCode() == other.hashCode();
        }
    }

}