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Mock objects library for java
/*
* Copyright (c) 2007 Mockito contributors
* This program is made available under the terms of the MIT License.
*/
package org.mockito.internal.util.reflection;
import org.mockito.exceptions.base.MockitoException;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
/**
* Initialize a field with type instance if a default constructor can be found.
*
*
* If the given field is already initialized, then the actual instance is returned.
* This initializer doesn't work with inner classes, local classes, interfaces or abstract types.
*
*
*/
public class FieldInitializer {
private Object fieldOwner;
private Field field;
private ConstructorInstantiator instantiator;
/**
* Prepare initializer with the given field on the given instance.
*
*
* This constructor fail fast if the field type cannot be handled.
*
*
* @param fieldOwner Instance of the test.
* @param field Field to be initialize.
*/
public FieldInitializer(Object fieldOwner, Field field) {
this(fieldOwner, field, new NoArgConstructorInstantiator(fieldOwner, field));
}
/**
* Prepare initializer with the given field on the given instance.
*
*
* This constructor fail fast if the field type cannot be handled.
*
*
* @param fieldOwner Instance of the test.
* @param field Field to be initialize.
*/
public FieldInitializer(Object fieldOwner, Field field, ConstructorArgumentResolver argResolver) {
this(fieldOwner, field, new ParameterizedConstructorInstantiator(fieldOwner, field, argResolver));
}
private FieldInitializer(Object fieldOwner, Field field, ConstructorInstantiator instantiator) {
if(new FieldReader(fieldOwner, field).isNull()) {
checkNotLocal(field);
checkNotInner(field);
checkNotInterface(field);
checkNotAbstract(field);
}
this.fieldOwner = fieldOwner;
this.field = field;
this.instantiator = instantiator;
}
/**
* Initialize field if no initialized and return the actual instance.
*
* @return Actual field instance.
*/
public FieldInitializationReport initialize() {
final AccessibilityChanger changer = new AccessibilityChanger();
changer.enableAccess(field);
try {
return acquireFieldInstance();
} catch(IllegalAccessException e) {
throw new MockitoException("Problems initializing field '" + field.getName() + "' of type '" + field.getType().getSimpleName() + "'", e);
} finally {
changer.safelyDisableAccess(field);
}
}
private void checkNotLocal(Field field) {
if(field.getType().isLocalClass()) {
throw new MockitoException("the type '" + field.getType().getSimpleName() + "' is a local class.");
}
}
private void checkNotInner(Field field) {
if(field.getType().isMemberClass() && !Modifier.isStatic(field.getType().getModifiers())) {
throw new MockitoException("the type '" + field.getType().getSimpleName() + "' is an inner class.");
}
}
private void checkNotInterface(Field field) {
if(field.getType().isInterface()) {
throw new MockitoException("the type '" + field.getType().getSimpleName() + "' is an interface.");
}
}
private void checkNotAbstract(Field field) {
if(Modifier.isAbstract(field.getType().getModifiers())) {
throw new MockitoException("the type '" + field.getType().getSimpleName() + " is an abstract class.");
}
}
private FieldInitializationReport acquireFieldInstance() throws IllegalAccessException {
Object fieldInstance = field.get(fieldOwner);
if(fieldInstance != null) {
return new FieldInitializationReport(fieldInstance, false);
}
instantiator.instantiate();
return new FieldInitializationReport(field.get(fieldOwner), true);
}
/**
* Represents the strategy used to resolve actual instances
* to be given to a constructor given the argument types.
*/
public interface ConstructorArgumentResolver {
/**
* Try to resolve instances from types.
*
*
* Checks on the real argument type or on the correct argument number
* will happen during the field initialization {@link FieldInitializer#initialize()}.
* I.e the only responsibility of this method, is to provide instances if possible.
*
*
* @param argTypes Constructor argument types, should not be null.
* @return The argument instances to be given to the constructor, should not be null.
*/
Object[] resolveTypeInstances(Class... argTypes);
}
private interface ConstructorInstantiator {
Object instantiate();
}
/**
* Constructor instantiating strategy for no-arg constructor.
*
*
* If a no-arg constructor can be found then the instance is created using
* this constructor.
* Otherwise a technical MockitoException is thrown.
*
*/
static class NoArgConstructorInstantiator implements ConstructorInstantiator {
private Object testClass;
private Field field;
/**
* Internal, checks are done by FieldInitializer.
* Fields are assumed to be accessible.
*/
NoArgConstructorInstantiator(Object testClass, Field field) {
this.testClass = testClass;
this.field = field;
}
public Object instantiate() {
final AccessibilityChanger changer = new AccessibilityChanger();
Constructor constructor = null;
try {
constructor = field.getType().getDeclaredConstructor();
changer.enableAccess(constructor);
final Object[] noArg = new Object[0];
Object newFieldInstance = constructor.newInstance(noArg);
new FieldSetter(testClass, field).set(newFieldInstance);
return field.get(testClass);
} catch (NoSuchMethodException e) {
throw new MockitoException("the type '" + field.getType().getSimpleName() + "' has no default constructor", e);
} catch (InvocationTargetException e) {
throw new MockitoException("the default constructor of type '" + field.getType().getSimpleName() + "' has raised an exception (see the stack trace for cause): " + e.getTargetException().toString(), e);
} catch (InstantiationException e) {
throw new MockitoException("InstantiationException (see the stack trace for cause): " + e.toString(), e);
} catch (IllegalAccessException e) {
throw new MockitoException("IllegalAccessException (see the stack trace for cause): " + e.toString(), e);
} finally {
if(constructor != null) {
changer.safelyDisableAccess(constructor);
}
}
}
}
/**
* Constructor instantiating strategy for parameterized constructors.
*
*
* Choose the constructor with the highest number of parameters, then
* call the ConstructorArgResolver to get actual argument instances.
* If the argResolver fail, then a technical MockitoException is thrown is thrown.
* Otherwise the instance is created with the resolved arguments.
*
*/
static class ParameterizedConstructorInstantiator implements ConstructorInstantiator {
private Object testClass;
private Field field;
private ConstructorArgumentResolver argResolver;
private Comparator> byParameterNumber = new Comparator>() {
public int compare(Constructor constructorA, Constructor constructorB) {
return constructorB.getParameterTypes().length - constructorA.getParameterTypes().length;
}
};
/**
* Internal, checks are done by FieldInitializer.
* Fields are assumed to be accessible.
*/
ParameterizedConstructorInstantiator(Object testClass, Field field, ConstructorArgumentResolver argumentResolver) {
this.testClass = testClass;
this.field = field;
this.argResolver = argumentResolver;
}
public Object instantiate() {
final AccessibilityChanger changer = new AccessibilityChanger();
Constructor constructor = null;
try {
constructor = biggestConstructor(field.getType());
changer.enableAccess(constructor);
final Object[] args = argResolver.resolveTypeInstances(constructor.getParameterTypes());
Object newFieldInstance = constructor.newInstance(args);
new FieldSetter(testClass, field).set(newFieldInstance);
return field.get(testClass);
} catch (IllegalArgumentException e) {
throw new MockitoException("internal error : argResolver provided incorrect types for constructor " + constructor + " of type " + field.getType().getSimpleName(), e);
} catch (InvocationTargetException e) {
throw new MockitoException("the constructor of type '" + field.getType().getSimpleName() + "' has raised an exception (see the stack trace for cause): " + e.getTargetException().toString(), e);
} catch (InstantiationException e) {
throw new MockitoException("InstantiationException (see the stack trace for cause): " + e.toString(), e);
} catch (IllegalAccessException e) {
throw new MockitoException("IllegalAccessException (see the stack trace for cause): " + e.toString(), e);
} finally {
if(constructor != null) {
changer.safelyDisableAccess(constructor);
}
}
}
private void checkParameterized(Constructor constructor, Field field) {
if(constructor.getParameterTypes().length == 0) {
throw new MockitoException("the field " + field.getName() + " of type " + field.getType() + " has no parameterized constructor");
}
}
private Constructor biggestConstructor(Class clazz) {
final List> constructors = Arrays.asList(clazz.getDeclaredConstructors());
Collections.sort(constructors, byParameterNumber);
Constructor constructor = constructors.get(0);
checkParameterized(constructor, field);
return constructor;
}
}
}