Byte Buddy Gradle Plugin

The Byte Buddy Gradle Plugin enables you to apply bytecode enhancements during the build process. To activate this process, add the following sections to your project Gradle build file:

build.gradle

plugins {
  id 'net.bytebuddy.byte-buddy-gradle-plugin' version 'LATEST'
}

configurations {
  examplePlugin "foo:bar:1.0"
}

byteBuddy {
  transformation {
    plugin = "com.example.junit.HookInstallingPlugin"
    classPath = configurations.examplePlugin
  }
}

This configuration informs Gradle to transform all classes by the goal using the transformation specified by HookInstallingPlugin within the foo:bar:1.0 artifact.

HookInstallingPlugin.java

package com.example.junit;

import static net.bytebuddy.matcher.ElementMatchers.*;

import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;

import net.bytebuddy.build.Plugin;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.dynamic.DynamicType.Builder;
import net.bytebuddy.implementation.MethodDelegation;

public class HookInstallingPlugin implements Plugin {

    @Override
    public boolean matches(TypeDescription target) {
        return target.getName().endsWith("Test");
    }

    @Override
    public Builder<?> apply(Builder<?> builder, TypeDescription typeDescription) {
        return builder.method(isAnnotatedWith(anyOf(Test.class, Before.class, After.class))
                .or(isStatic().and(isAnnotatedWith(anyOf(BeforeClass.class, AfterClass.class)))))
                .intercept(MethodDelegation.to(SampleInterceptor.class))
                .implement(Hooked.class);
    }
}

This example transformation specifies that Byte Buddy should install a method interceptor (defined by SampleInterceptor) on all test classes with a name ending with Test. The interceptor is added to all methods with the annotations @Test, @Before, @After, @BeforeClass, or @AfterClass. This transformation also adds a marker interface Hooked so that we can identify enhanced classes at runtime.

A plugin can declare a constructor that can take arguments of type File, BuildLogger or a Gradle-specific Logger where the class file root directory or an appropriate logger is provided. It is also possible to supply an argument explicitly by specifying an argument in the plugin configuration.