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JMockit is a Java toolkit for automated developer testing. It contains mocking/faking APIs and a code coverage tool, supporting both JUnit and TestNG. The mocking APIs allow all kinds of Java code, without testability restrictions, to be tested in isolation from selected dependencies.

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/*
 * Copyright (c) 2006 Rogério Liesenfeld
 * This file is subject to the terms of the MIT license (see LICENSE.txt).
 */
package mockit;

import static java.lang.reflect.Modifier.*;

import mockit.internal.classGeneration.*;
import mockit.internal.util.*;
import mockit.internal.util.EmptyProxy.*;

/**
 * Provides utility methods that enable access to ("de-encapsulate") otherwise non-accessible fields, methods, and
 * constructors.
 *
 * @see #getField(Object, String)
 * @see #setField(Object, String, Object)
 * @see #invoke(Object, String, Object...)
 * @see #newInstance(String, Object...)
 */
@SuppressWarnings("ConstantConditions")
public final class Deencapsulation
{
   private Deencapsulation() {}

   /**
    * Gets the value of a non-accessible (eg {@code private}) field from a given object.
    *
    * @param objectWithField the instance from which to get the field value
    * @param fieldName the name of the field to get
    * @param  interface or class type to which the returned value should be assignable
    *
    * @throws IllegalArgumentException if the desired field is not found
    *
    * @see #getField(Object, Class)
    * @see #getField(Class, String)
    * @see #setField(Object, String, Object)
    */
   public static  T getField(Object objectWithField, String fieldName)
   {
      return FieldReflection.getField(objectWithField.getClass(), fieldName, objectWithField);
   }

   /**
    * Gets the value of a non-accessible (eg {@code private}) field from a given object, assuming there is only
    * one field declared in the class of the given object whose type can receive values of the specified field type.
    *
    * @param objectWithField the instance from which to get the field value
    * @param fieldType the declared type of the field, or a sub-type of the declared field type
    *
    * @throws IllegalArgumentException if either the desired field is not found, or more than one is
    *
    * @see #getField(Object, String)
    * @see #getField(Class, String)
    * @see #setField(Object, Object)
    */
   public static  T getField(Object objectWithField, Class fieldType)
   {
      return FieldReflection.getField(objectWithField.getClass(), fieldType, objectWithField);
   }

   /**
    * Gets the value of a non-accessible static field defined in a given class.
    *
    * @param classWithStaticField the class from which to get the field value
    * @param fieldName the name of the static field to get
    * @param  interface or class type to which the returned value should be assignable
    *
    * @throws IllegalArgumentException if the desired field is not found
    *
    * @see #getField(Class, Class)
    * @see #getField(Object, String)
    * @see #setField(Class, String, Object)
    */
   public static  T getField(Class classWithStaticField, String fieldName)
   {
      return FieldReflection.getField(classWithStaticField, fieldName, null);
   }

   /**
    * Gets the value of a non-accessible static field defined in a given class, assuming there is only one
    * field declared in the given class whose type can receive values of the specified field type.
    *
    * @param classWithStaticField the class from which to get the field value
    * @param fieldType the declared type of the field, or a sub-type of the declared field type
    * @param  interface or class type to which the returned value should be assignable
    *
    * @throws IllegalArgumentException if either the desired field is not found, or more than one is
    *
    * @see #getField(Class, String)
    * @see #getField(Object, Class)
    * @see #setField(Class, Object)
    */
   public static  T getField(Class classWithStaticField, Class fieldType)
   {
      return FieldReflection.getField(classWithStaticField, fieldType, null);
   }

   /**
    * Sets the value of a non-accessible field on a given object.
    *
    * @param objectWithField the instance on which to set the field value
    * @param fieldName the name of the field to set
    * @param fieldValue the value to set the field to
    *
    * @throws IllegalArgumentException if the desired field is not found
    *
    * @see #setField(Class, String, Object)
    * @see #setField(Object, Object)
    * @see #getField(Object, String)
    */
   public static void setField(Object objectWithField, String fieldName, Object fieldValue)
   {
      FieldReflection.setField(objectWithField.getClass(), objectWithField, fieldName, fieldValue);
   }

   /**
    * Sets the value of a non-accessible field on a given object.
    * The field is looked up by the type of the given field value instead of by name.
    *
    * @throws IllegalArgumentException if either the desired field is not found, or more than one is
    *
    * @see #setField(Object, String, Object)
    * @see #setField(Class, String, Object)
    * @see #getField(Object, String)
    */
   public static void setField(Object objectWithField, Object fieldValue)
   {
      FieldReflection.setField(objectWithField.getClass(), objectWithField, null, fieldValue);
   }

   /**
    * Sets the value of a non-accessible static field on a given class.
    *
    * @param classWithStaticField the class on which the static field is defined
    * @param fieldName the name of the field to set
    * @param fieldValue the value to set the field to
    *
    * @throws IllegalArgumentException if the desired field is not found
    *
    * @see #setField(Class, Object)
    * @see #setField(Object, String, Object)
    * @see #getField(Class, String)
    */
   public static void setField(Class classWithStaticField, String fieldName, Object fieldValue)
   {
      FieldReflection.setField(classWithStaticField, null, fieldName, fieldValue);
   }

   /**
    * Sets the value of a non-accessible static field on a given class.
    * The field is looked up by the type of the given field value instead of by name.
    *
    * @param classWithStaticField the class on which the static field is defined
    * @param fieldValue the value to set the field to
    *
    * @throws IllegalArgumentException if either the desired field is not found, or more than one is
    *
    * @see #setField(Class, String, Object)
    * @see #setField(Object, Object)
    * @see #getField(Class, Class)
    */
   public static void setField(Class classWithStaticField, Object fieldValue)
   {
      FieldReflection.setField(classWithStaticField, null, null, fieldValue);
   }

   /**
    * Invokes a non-accessible (eg {@code private}) instance method from a given class with the given arguments.
    *
    * @param objectWithMethod the instance on which the invocation is to be done
    * @param methodName the name of the method to invoke
    * @param parameterTypes the types of the parameters as declared in the desired method
    * @param methodArgs zero or more parameter values for the invocation
    * @param  type to which the returned value should be assignable
    *
    * @return the return value from the invoked method
    *
    * @see #invoke(Class, String, Object...)
    */
   public static  T invoke(
      Object objectWithMethod, String methodName, Class[] parameterTypes, Object... methodArgs)
   {
      Class theClass = objectWithMethod.getClass();
      return MethodReflection.invoke(theClass, objectWithMethod, methodName, parameterTypes, methodArgs);
   }

   /**
    * Invokes a non-accessible (eg {@code private}) instance method from a given class with the given arguments.
    *
    * @param objectWithMethod the instance on which the invocation is to be done
    * @param methodName the name of the method to invoke
    * @param nonNullArgs zero or more non-null parameter values for the invocation; if a null value needs to be passed,
    * the {@code Class} object for the corresponding parameter type must be passed instead
    * @param  type to which the returned value should be assignable
    *
    * @return the return value from the invoked method
    *
    * @throws IllegalArgumentException if a null reference was provided for a parameter
    *
    * @see #invoke(Class, String, Object...)
    */
   public static  T invoke(Object objectWithMethod, String methodName, Object... nonNullArgs)
   {
      Class theClass = objectWithMethod.getClass();
      return MethodReflection.invoke(theClass, objectWithMethod, methodName, nonNullArgs);
   }

   /**
    * Invokes a non-accessible (eg {@code private}) {@code static} method with the given arguments.
    *
    * @param classWithStaticMethod the class on which the invocation is to be done
    * @param methodName the name of the static method to invoke
    * @param parameterTypes the types of the parameters as declared in the desired method
    * @param methodArgs zero or more parameter values for the invocation
    * @param  type to which the returned value should be assignable
    *
    * @return the return value from the invoked method
    *
    * @see #invoke(String, String, Object...)
    */
   public static  T invoke(
      Class classWithStaticMethod, String methodName, Class[] parameterTypes, Object... methodArgs)
   {
      return MethodReflection.invoke(classWithStaticMethod, null, methodName, parameterTypes, methodArgs);
   }

   /**
    * Invokes a non-accessible (eg {@code private}) {@code static} method with the given arguments.
    *
    * @param classWithStaticMethod the class on which the invocation is to be done
    * @param methodName the name of the static method to invoke
    * @param nonNullArgs zero or more non-null parameter values for the invocation; if a null value needs to be passed,
    * the {@code Class} object for the corresponding parameter type must be passed instead
    * @param  type to which the returned value should be assignable
    *
    * @return the return value from the invoked method
    *
    * @throws IllegalArgumentException if a null reference was provided for a parameter
    *
    * @see #invoke(String, String, Object...)
    */
   public static  T invoke(Class classWithStaticMethod, String methodName, Object... nonNullArgs)
   {
      return MethodReflection.invoke(classWithStaticMethod, null, methodName, nonNullArgs);
   }

   /**
    * Invokes a non-accessible (eg {@code private}) {@code static} method with the given arguments.
    *
    * @param classWithStaticMethod the (fully qualified) name of the class on which the invocation is to be done;
    * must not be null
    * @param methodName the name of the static method to invoke
    * @param nonNullArgs zero or more non-null parameter values for the invocation; if a null value needs to be passed,
    * the {@code Class} object for the corresponding parameter type must be passed instead
    * @param  type to which the returned value should be assignable
    *
    * @return the return value from the invoked method
    *
    * @throws IllegalArgumentException if a null reference was provided for a parameter
    *
    * @see #invoke(Class, String, Object...)
    */
   public static  T invoke(String classWithStaticMethod, String methodName, Object... nonNullArgs)
   {
      Class theClass = ClassLoad.loadClass(classWithStaticMethod);
      return MethodReflection.invoke(theClass, null, methodName, nonNullArgs);
   }

   /**
    * Creates a new instance of a given non-accessible class, invoking the constructor which has the specified parameter
    * types.
    *
    * @param className the fully qualified name of the desired class
    * @param parameterTypes the formal parameter types for the desired constructor, possibly empty
    * @param initArgs the invocation arguments for the constructor, which must be consistent with the specified
    * parameter types
    * @param  type to which the returned instance should be assignable
    *
    * @return a newly created instance of the specified class, initialized through the specified constructor and
    * arguments
    *
    * @see #newInstance(String, Object...)
    * @see #newInstance(Class, Class[], Object...)
    * @see #newInnerInstance(String, Object, Object...)
    */
   public static  T newInstance(String className, Class[] parameterTypes, Object... initArgs)
   {
      return ConstructorReflection.newInstance(className, parameterTypes, initArgs);
   }

   /**
    * Creates a new instance of a given class, invoking the constructor which has the specified parameter types.
    *
    * @param classToInstantiate the class to be instantiated
    * @param parameterTypes the formal parameter types for the desired constructor, possibly empty
    * @param initArgs the invocation arguments for the constructor, which must be consistent with the specified
    * parameter types
    * @param  type to which the returned instance should be assignable
    *
    * @return a newly created instance of the specified class, initialized through the specified constructor and
    * arguments
    *
    * @see #newInstance(Class, Object...)
    * @see #newInnerInstance(Class, Object, Object...)
    * @see #newInstance(String, Class[], Object...)
    */
   public static  T newInstance(Class classToInstantiate, Class[] parameterTypes, Object... initArgs)
   {
      return ConstructorReflection.newInstance(classToInstantiate, parameterTypes, initArgs);
   }

   /**
    * Creates a new instance of a given non-accessible class, invoking the constructor which has parameters matching the
    * number, order, and types of the given non-null arguments.
    *
    * @param nonNullArgs zero or more non-null parameter values for the invocation; if a null value needs to be passed,
    * the {@code Class} object for the corresponding parameter type must be passed instead
    * @param  type to which the returned instance should be assignable
    *
    * @return a newly created instance of the specified class, initialized with the given arguments
    *
    * @throws IllegalArgumentException if a null reference was provided for a parameter, or if no constructor was found
    * that matched the given argument types
    *
    * @see #newInnerInstance(String, Object, Object...)
    * @see #newInstance(Class, Object...)
    * @see #newInstance(String, Class[], Object...)
    */
   public static  T newInstance(String className, Object... nonNullArgs)
   {
      return ConstructorReflection.newInstance(className, nonNullArgs);
   }

   /**
    * Creates a new instance of a given class, invoking the constructor which has parameters matching the number, order,
    * and types of the given non-null arguments.
    *
    * @param nonNullArgs zero or more non-null parameter values for the invocation; if a null value needs to be passed,
    * the {@code Class} object for the corresponding parameter type must be passed instead
    * @param  type to which the returned instance should be assignable
    *
    * @return a newly created instance of the specified class, initialized with the given arguments
    *
    * @throws IllegalArgumentException if a null reference was provided for a parameter, or if no constructor was found
    * that matched the given argument types
    *
    * @see #newInnerInstance(Class, Object, Object...)
    * @see #newInstance(String, Object...)
    * @see #newInstance(String, Class[], Object...)
    */
   public static  T newInstance(Class classToInstantiate, Object... nonNullArgs)
   {
      return ConstructorReflection.newInstance(classToInstantiate, nonNullArgs);
   }

   /**
    * The same as {@link #newInstance(String, Class[], Object...)}, but for instantiating an inner non-accessible class
    * of some other class, and where all other (if any) initialization arguments are known to be non-null.
    *
    * @param innerClassSimpleName the inner class simple name, that is, the part after the "$" character in its full
    * name
    * @param outerClassInstance the outer class instance to which the inner class instance will belong
    * @param nonNullArgs zero or more non-null parameter values for the invocation; if a null value needs to be passed,
    * the {@code Class} object for the corresponding parameter type must be passed instead
    * @param  type to which the returned instance should be assignable
    *
    * @return a newly created instance of the specified inner class, initialized with the given arguments
    *
    * @throws IllegalArgumentException if a {@code null} reference was provided for a parameter, or the class given to
    * instantiate is not an inner class, or a matching constructor is not found
    *
    * @see #newInnerInstance(Class, Object, Object...)
    */
   public static  T newInnerInstance(String innerClassSimpleName, Object outerClassInstance, Object... nonNullArgs)
   {
      return ConstructorReflection.newInnerInstance(innerClassSimpleName, outerClassInstance, nonNullArgs);
   }

   /**
    * The same as {@link #newInstance(String, Class[], Object...)}, but for instantiating an inner class of some other
    * class, and where all other (if any) initialization arguments are known to be non-null.
    *
    * @param innerClassToInstantiate the inner class to be instantiated
    * @param outerClassInstance the outer class instance to which the inner class instance will belong
    * @param nonNullArgs zero or more non-null parameter values for the invocation; if a null value needs to be passed,
    * the {@code Class} object for the corresponding parameter type must be passed instead
    * @param  type to which the returned instance should be assignable
    *
    * @return a newly created instance of the specified inner class, initialized with the given arguments
    *
    * @throws IllegalArgumentException if a {@code null} reference was provided for a parameter, or the class given to
    * instantiate is not an inner class, or a matching constructor is not found
    *
    * @see #newInnerInstance(String, Object, Object...)
    */
   public static  T newInnerInstance(
      Class innerClassToInstantiate, Object outerClassInstance, Object... nonNullArgs)
   {
      return ConstructorReflection.newInnerInstance(innerClassToInstantiate, outerClassInstance, nonNullArgs);
   }

   /**
    * Creates a new instance of a given class, without invoking any constructor.
    * If the given class is {@code abstract} or an {@code interface}, then a concrete class is created, with empty
    * implementations for the {@code abstract}/{@code interface} methods.
    *
    * @param classToInstantiate the class to be instantiated
    * @param  type to which the returned instance should be assignable
    *
    * @return a newly created instance of the specified class, with any instance fields left uninitialized
    *
    * @see #newInstance(Class, Object...)
    * @see #newInstance(String, Class[], Object...)
    * @see #newInnerInstance(Class, Object, Object...)
    */
   public static  T newUninitializedInstance(Class classToInstantiate)
   {
      if (classToInstantiate.isInterface()) {
         T instance = Impl.newEmptyProxy(classToInstantiate.getClassLoader(), classToInstantiate);
         return instance;
      }
      else if (isAbstract(classToInstantiate.getModifiers())) {
         classToInstantiate = new ConcreteSubclass(classToInstantiate).generateClass();
      }

      return ConstructorReflection.newUninitializedInstance(classToInstantiate);
   }
}