Package com.tngtech.jgiven.impl

Class ByteBuddyStageClassCreator

java.lang.Object

com.tngtech.jgiven.impl.ByteBuddyStageClassCreator

All Implemented Interfaces:

StageClassCreator

public class ByteBuddyStageClassCreator
extends Object
implements StageClassCreator

Creates JGiven stage subclasses at runtime using ByteBuddy.

The class loading strategy is chosen in three tiers, in order of preference:

1. Reflection-based injection (ClassLoadingStrategy.Default.INJECTION) — used when ClassInjector.UsingReflection.isAvailable() returns true. This is the case when the class to be instrumented is not barred from injection via the Jave module system. (Mostly the case up to Java 21) The generated subclass is injected into the same classloader as the stage class via sun.misc.Unsafe/defineClass reflection, which preserves package membership.
2. Lookup-based injection (ClassLoadingStrategy.UsingLookup) — used when reflective injection is unavailable but ClassInjector.UsingLookup.isAvailable() returns true and a MethodHandles.Lookup with PACKAGE/MODULE privileges over the stage class's package can be obtained via MethodHandles.privateLookupIn(java.lang.Class<?>, java.lang.invoke.MethodHandles.Lookup). The generated subclass is again injected into the stage class's classloader, preserving package membership. This tier is reached on Java 9+ runtimes that have not opened java.base/java.lang to reflection. If privateLookupIn fails (typically because the user's JPMS module does not --add-opens its package to JGiven), a single WARN-level log message is emitted and the strategy falls through to WRAPPER.
3. Wrapping (ClassLoadingStrategy.Default.WRAPPER) — fallback when neither injector is available, or when the lookup tier cannot acquire a usable Lookup. The generated subclass is placed in a separate child classloader. Package-private stages cannot be instrumented under WRAPPER; the user must either --add-opens their stage class's package or move the stage class to the unnamed module / classpath.

Subclasses may override getClassLoadingStrategy(Class) to take a different decision.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	ByteBuddyStageClassCreator.StepInterceptorGetterSetter
static class	ByteBuddyStageClassCreator.StepInterceptorSetter

Field Summary

Fields

Modifier and Type	Field	Description
static final String	INTERCEPTOR_FIELD_NAME
static final String	SETTER_NAME

Constructor Summary

Constructors

Constructor	Description
ByteBuddyStageClassCreator()

Method Summary

Modifier and Type	Method	Description
<T> Class<? extends T>	createStageClass(Class<T> stageClass)
protected ClassLoader	getClassLoader(Class<?> stageClass)
protected net.bytebuddy.dynamic.loading.ClassLoadingStrategy<ClassLoader>	getClassLoadingStrategy(Class<?> stageClass)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

INTERCEPTOR_FIELD_NAME

public static final String INTERCEPTOR_FIELD_NAME

See Also:

• Constant Field Values

SETTER_NAME

public static final String SETTER_NAME

See Also:

• Constant Field Values

Constructor Details

ByteBuddyStageClassCreator

public ByteBuddyStageClassCreator()

Method Details

createStageClass

public <T> Class<? extends T> createStageClass(Class<T> stageClass)

Specified by:

createStageClass in interface StageClassCreator

getClassLoadingStrategy

protected net.bytebuddy.dynamic.loading.ClassLoadingStrategy<ClassLoader> getClassLoadingStrategy(Class<?> stageClass)

getClassLoader

protected ClassLoader getClassLoader(Class<?> stageClass)