mockit.Tested Maven / Gradle / Ivy

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

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

/**
 * Indicates a class to be tested, with optional automatic instantiation and/or automatic injection of dependencies.
 * This annotation is applicable to instance fields of a test class, and to test method parameters; alternatively, it can be used as a
 * meta-annotation on a user-defined annotation which, in turn, needs to have {@linkplain RetentionPolicy#RUNTIME runtime}
 * {@linkplain Retention retention} and be {@linkplain Target applicable} to {@linkplain ElementType#FIELD fields} and/or
 * {@linkplain ElementType#PARAMETER parameters}.
 * 
 * Every non-final tested field and every tested parameter is eligible for automatic instantiation and initialization.
 * By default, automatic instantiation occurs just before a test method is executed.
 * This default can be changed by specifying the {@link #availableDuringSetup} optional attribute as true in a tested field
 * declaration (it is ignored if applied to a tested parameter).
 * 

 * Whenever automatic creation occurs, a suitable instance of the tested class is created, initialized, and assigned to the tested field or
 * passed as argument to the tested parameter.
 * Available {@linkplain Injectable injectables} and other @Tested values are used, either as argument values for the chosen
 * constructor of the tested class, or as values to set into injected fields of the newly-created tested object.
 * For a given tested object, only preceding tested objects (if any) are regarded as available for injection;
 * other such objects declared after the one being created are disregarded.
 * @Tested parameters precede any @Tested fields.
 * 

 * For constructor injection, all constructor parameters (if any) must be satisfied with available tested/injectable values.
 * If the tested class has a constructor annotated with the standard CDI annotation "@Inject", then it is the one to be used;
 * otherwise, if there are multiple satisfiable constructors then the one with the most parameters and the widest accessibility
 * (ie, first public, then protected, then package-private, and finally private) is chosen.
 * The matching between injectable values and constructor parameters is done by type when there is only one parameter of a given
 * type; otherwise, by type and name.
 * 

 * Field injection is performed on all tested objects, even when it was not instantiated automatically.
 * Only non-final fields are considered, between those declared in the tested class itself or in one of its super-classes; at
 * this time constructor injection already occurred, so only fields which remain uninitialized are targeted.
 * For each such target field, the value of a still unused injectable of a matching type is assigned, if any is available.
 * When a tested object has multiple target fields of a matching type, not just the type but also the name of each field will be
 * used when looking for available injectables.
 * Finally, if there is no matching and available injectable value for a given target field, it is left unassigned, unless the target field
 * is for a required dependency; note that all fields marked with a DI annotation (such as @Inject, @Autowired,
 * etc.) indicate required dependencies by default (the use of "@Autowired(required = false)" is respected, if present).
 * 

 * Tested fields/parameters whose declared type is primitive, a primitive wrapper, numeric, or an enum can use the {@link #value} attribute
 * to specify an initial value from a string.
 * 

 * Custom names specified in field annotations from Java EE (@Resource(name), @Named) or the Spring framework
 * (@Qualifier) are used when looking for a matching @Injectable or @Tested value.
 * When such a name contains a - (dash) or . (dot) character, the corresponding camel-cased name is used instead.
 * 

 * Whenever constructor or field injection is used, the value of each injectable goes into at most one matching constructor
 * parameter or instance field of a tested class.
 * 

 * The tested class can be abstract.
 * In this case, if the tested field is left null then a subclass implementing all abstract methods is automatically generated and
 * instantiated.
 * The abstract method implementations are automatically mocked so that expectations can be recorded or verified on them.
 * 

 * When the {@link #fullyInitialized} attribute is true, all eligible fields in the tested object will get initialized with a
 * suitable instance, which itself is recursively initialized in the same way.
 *
 * @see Tutorial
 */
@Retention(RUNTIME)
@Target({FIELD, PARAMETER, ANNOTATION_TYPE, METHOD})
public @interface Tested
{
   /**
    * Specifies a literal value when the type of the tested field/parameter is String, a primitive or wrapper type, a number type,
    * or an enum type.
    * For a primitive/wrapper/number type, the value provided must be convertible to it.
    * For an enum type, the given textual value must equal the name of one of the possible enum values.
    */
   String value() default "";

   /**
    * Indicates that each non-final field of the tested object that is eligible for injection should be assigned a value, which can
    * be an available {@linkplain Injectable @Injectable} or @Tested value of a type assignable to the field type, or a real
    * (unmocked) instance of the field type.
    * 

    * Non-eligible fields are those that have already being assigned from a constructor, or that have a primitive, array, annotation, or JRE
    * type (with the exception of the types described below, which are given special treatment).
    * Also non-eligible are any static or volatile fields, unless annotated with an injection annotation (one of
    * @Inject, @Resource, @Autowired, @EJB, @PersistenceContext, or @PersistenceUnit).
    * 

    * For each field of a reference type that would otherwise remain null, an attempt is made to automatically create and
    * recursively initialize a suitable real instance.
    * For this attempt to succeed, the type of the field must either be a concrete class having a constructor that can be satisfied by
    * available tested/injectable values and/or by recursively created dependencies, or a known interface (see below) for which a real
    * instance can be created.
    * 

    * Constructor injection is also supported.
    * In this case, the same rules used for injected fields apply to the parameters of the constructor that gets chosen for automatic
    * instantiation.
    * 

    * Currently, the following standard types (some of which are Java EE interfaces) have special support:
    * 

    *    
    *       {@link java.util.logging.Logger}:
    *       a logger is automatically {@linkplain java.util.logging.Logger#getLogger(String) created} with the name of the tested class.
    *    
    *    
    *       {@link javax.sql.DataSource}: a JDBC data source is created and configured according to a matching
    *       {@link javax.annotation.sql.DataSourceDefinition @DataSourceDefinition} in the tested class.
    *    
    *    
    *       {@link javax.inject.Provider Provider<T>}: a provider which produces an instance of type T is injected.
    *    
    *    
    *       JPA interfaces {@link javax.persistence.EntityManagerFactory} and {@link javax.persistence.EntityManager}:
    *       created through calls to {@link javax.persistence.Persistence#createEntityManagerFactory(String)} and
    *       {@link javax.persistence.EntityManagerFactory#createEntityManager()}, provided a suitable META-INF/persistence.xml file
    *       is available in the runtime classpath.
    *    
    *    
    *       Servlet interfaces {@link javax.servlet.ServletContext} and {@link javax.servlet.http.HttpSession}:
    *       objects that emulate the servlet context and HTTP session are automatically created for use in tests.
    *    
    *    
    *       {@link javax.enterprise.context.Conversation}: an object that emulates a web application's conversation context is created.
    *    
    * 
    */
   boolean fullyInitialized() default false;

   /**
    * Indicates whether the tested class gets instantiated and initialized before the execution of test setup methods (ie, those
    * annotated as @Before or @BeforeMethod), or after them.
    * 
    * Typically, the early creation of tested objects is useful in a test setup method, which can use them for the initialization of other
    * objects.
    * Another potential use is to affect the initialization of other tested objects in the same test class, during their creation
    * after setup.
    * Finally, objects made available during setup are also available during the execution of any tear-down methods.
    */
   boolean availableDuringSetup() default false;
}