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Mock objects library for java
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/*
 * Copyright (c) 2007 Mockito contributors
 * This program is made available under the terms of the MIT License.
 */
package org.mockito;

import static java.lang.annotation.ElementType.*;

import java.lang.annotation.Annotation;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import java.lang.reflect.Field;

import org.mockito.configuration.AnnotationEngine;
import org.mockito.configuration.DefaultMockitoConfiguration;
import org.mockito.exceptions.Reporter;
import org.mockito.exceptions.base.MockitoException;
import org.mockito.internal.configuration.GlobalConfiguration;
import org.mockito.internal.util.reflection.FieldSetter;
import org.mockito.runners.MockitoJUnitRunner;

/**
 * MockitoAnnotations.initMocks(this); initializes fields annotated with Mockito annotations.
 *   
 * 

 * Allows shorthand creation of objects required for testing. 
 * Minimizes repetitive mock creation code. 
 * Makes the test class more readable.
 * Makes the verification error easier to read because field name is used to identify the mock.
 * 
 * 
 *  *   public class ArticleManagerTest extends SampleBaseTestCase { 
 *     
 *       @Mock private ArticleCalculator calculator;
 *       @Mock private ArticleDatabase database;
 *       @Mock private UserProvider userProvider;
 *     
 *       private ArticleManager manager;
 *     
 *       @Before public void setup() {
 *           manager = new ArticleManager(userProvider, database, calculator);
 *       }
 *   }
 *   
 *   public class SampleBaseTestCase {
 *   
 *       @Before public void initMocks() {
 *           MockitoAnnotations.initMocks(this);
 *       }
 *   }
 * 
 * 
 * Read also about other annotations @{@link Spy}, @{@link Captor}, @{@link InjectMocks}
 * 

 * MockitoAnnotations.initMocks(this) method has to called to initialize annotated fields.
 * 

 * In above example, initMocks() is called in @Before (JUnit4) method of test's base class. 
 * For JUnit3 initMocks() can go to setup() method of a base class.
 * You can also put initMocks() in your JUnit runner (@RunWith) or use built-in runner: {@link MockitoJUnitRunner}
 */
public class MockitoAnnotations {

    /**
     * Use top-level {@link org.mockito.Mock} annotation instead
     * 

     * When @Mock annotation was implemented as an inner class then users experienced problems with autocomplete features in IDEs. 
     * Hence @Mock was made a top-level class.  
     * 

     * How to fix deprecation warnings? 
     * Typically, you can just search: import org.mockito.MockitoAnnotations.Mock; and replace with: import org.mockito.Mock;
     * 

     * If you're an existing user then sorry for making your code littered with deprecation warnings. 
     * This change was required to make Mockito better.
     */
    @Target( { FIELD })
    @Retention(RetentionPolicy.RUNTIME)
    @Deprecated
    public @interface Mock {}    
    
    /**
     * Initializes objects annotated with Mockito annotations for given testClass:
     *  @{@link org.mockito.Mock}, @{@link Spy}, @{@link Captor}, @{@link InjectMocks} 
     * 
     * See examples in javadoc for {@link MockitoAnnotations} class.
     */
    public static void initMocks(Object testClass) {
        if (testClass == null) {
            throw new MockitoException("testClass cannot be null. For info how to use @Mock annotations see examples in javadoc for MockitoAnnotations class");
        }
        
        Class clazz = testClass.getClass();
        while (clazz != Object.class) {
            scan(testClass, clazz);
            clazz = clazz.getSuperclass();
        }
    }

    static void scan(Object testClass, Class clazz) {
        AnnotationEngine annotationEngine = new GlobalConfiguration().getAnnotationEngine();
        Field[] fields = clazz.getDeclaredFields();
        for (Field field : fields) {
            if (annotationEngine.getClass() != new DefaultMockitoConfiguration().getAnnotationEngine().getClass()) {
                //this means user has his own annotation engine and we have to respect that.
                //we will do annotation processing the old way so that we are backwards compatible
                processAnnotationDeprecatedWay(annotationEngine, testClass, field);                
            } 
            //act 'the new' way
            annotationEngine.process(clazz, testClass);
        }
    }

    @SuppressWarnings("deprecation")
    static void processAnnotationDeprecatedWay(AnnotationEngine annotationEngine, Object testClass, Field field) {
        boolean alreadyAssigned = false;
        for(Annotation annotation : field.getAnnotations()) {
            Object mock = annotationEngine.createMockFor(annotation, field);
            if (mock != null) {
                throwIfAlreadyAssigned(field, alreadyAssigned);
                alreadyAssigned = true;                
                try {
                    new FieldSetter(testClass, field).set(mock);
                } catch (Exception e) {
                    throw new MockitoException("Problems setting field " + field.getName() + " annotated with "
                            + annotation, e);
                }
            }
        }
    }

    static void throwIfAlreadyAssigned(Field field, boolean alreadyAssigned) {
        if (alreadyAssigned) {
            new Reporter().moreThanOneAnnotationNotAllowed(field.getName());
        }
    }
}