Interface TestInstanceFactory

All Superinterfaces:

Extension, TestInstantiationAwareExtension

Functional Interface:

This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.

@FunctionalInterface
@API(status=STABLE,
     since="5.7")
public interface TestInstanceFactory
extends TestInstantiationAwareExtension

TestInstanceFactory defines the API for Extensions that wish to create test instances.

Common use cases include creating test instances with special construction requirements or acquiring the test instance from a dependency injection framework.

Extensions that implement TestInstanceFactory must be registered at the class level.

Warning

Only one TestInstanceFactory is allowed to be registered for any given test class. Registering multiple factories for any single test class will result in an exception being thrown for all tests in that class, in any subclass, and in any nested class. Note that any TestInstanceFactory registered in a superclass or enclosing class (i.e., in the case of a @Nested test class) is inherited. It is therefore the user's responsibility to ensure that only a single TestInstanceFactory is registered for any specific test class.

Constructor Requirements

Consult the documentation in Extension for details on constructor requirements.

ExtensionContext Scope

As of JUnit Jupiter 5.12, this API participates in the TestInstantiationAwareExtension contract. Implementations of this API may therefore choose to override getTestInstantiationExtensionContextScope(ExtensionContext) to require a test-method scoped ExtensionContext. See createTestInstance(TestInstanceFactoryContext, ExtensionContext) for further details.

Since:

5.3

See Also:

• createTestInstance(TestInstanceFactoryContext, ExtensionContext)
• TestInstanceFactoryContext
• TestInstancePostProcessor
• TestInstancePreDestroyCallback
• ParameterResolver

Nested Class Summary

Nested classes/interfaces inherited from interface TestInstantiationAwareExtension

TestInstantiationAwareExtension.ExtensionContextScope

Method Summary

Modifier and Type	Method	Description
Object	createTestInstance(TestInstanceFactoryContext factoryContext, ExtensionContext extensionContext)	Callback for creating a test instance for the supplied context.

Methods inherited from interface TestInstantiationAwareExtension

getTestInstantiationExtensionContextScope

Method Details

createTestInstance

Object createTestInstance(TestInstanceFactoryContext factoryContext,
 ExtensionContext extensionContext)
                   throws TestInstantiationException

Callback for creating a test instance for the supplied context.

By default, the supplied ExtensionContext represents the test class that's about to be instantiated. Extensions may override TestInstantiationAwareExtension.getTestInstantiationExtensionContextScope(ExtensionContext) to return TEST_METHOD in order to change the scope of the ExtensionContext to the test method, unless the PER_CLASS lifecycle is used. Changing the scope makes test-specific data available to the implementation of this method and allows keeping state on the test level by using the provided Store instance.

Note: the ExtensionContext supplied to a TestInstanceFactory will always return an empty Optional value from getTestInstance() since the test instance cannot exist before it has been created by a TestInstanceFactory or the framework itself.

Parameters:

factoryContext - the context for the test class to be instantiated; never null

extensionContext - the current extension context; never null

Returns:

the test instance; never null

Throws:

TestInstantiationException - if an error occurs while creating the test instance