Interface ParameterResolver

All Superinterfaces:

Extension, TestInstantiationAwareExtension

All Known Implementing Classes:

TypeBasedParameterResolver

@API(status=STABLE,
     since="5.0")
public interface ParameterResolver
extends TestInstantiationAwareExtension

ParameterResolver defines the API for Extensions that wish to dynamically resolve arguments for parameters at runtime.

If a constructor for a test class or a @Test, @BeforeEach, @AfterEach, @BeforeAll, or @AfterAll method declares a parameter, an argument for the parameter must be resolved at runtime by a ParameterResolver.

By default, when the methods in this interface are called for a test class constructor, the supplied ExtensionContext represents the test class that's about to be instantiated. Extensions may override TestInstantiationAwareExtension.getTestInstantiationExtensionContextScope(org.junit.jupiter.api.extension.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.

Constructor Requirements

Consult the documentation in Extension for details on constructor requirements.

Since:

5.0

See Also:

• supportsParameter(ParameterContext, ExtensionContext)
• resolveParameter(ParameterContext, ExtensionContext)
• ParameterContext
• TestInstanceFactory
• TestInstancePostProcessor
• TestInstancePreDestroyCallback

Nested Class Summary

Nested classes/interfaces inherited from interface org.junit.jupiter.api.extension.TestInstantiationAwareExtension

TestInstantiationAwareExtension.ExtensionContextScope

Method Summary

Modifier and Type	Method	Description
@Nullable Object	resolveParameter(ParameterContext parameterContext, ExtensionContext extensionContext)	Resolve an argument for the Parameter in the supplied ParameterContext for the supplied ExtensionContext.
boolean	supportsParameter(ParameterContext parameterContext, ExtensionContext extensionContext)	Determine if this resolver supports resolution of an argument for the Parameter in the supplied ParameterContext for the supplied ExtensionContext.

Methods inherited from interface org.junit.jupiter.api.extension.TestInstantiationAwareExtension

getTestInstantiationExtensionContextScope

Method Details

supportsParameter

boolean supportsParameter(ParameterContext parameterContext,
 ExtensionContext extensionContext)
                   throws ParameterResolutionException

Determine if this resolver supports resolution of an argument for the Parameter in the supplied ParameterContext for the supplied ExtensionContext.

The Method or Constructor in which the parameter is declared can be retrieved via ParameterContext.getDeclaringExecutable().

Parameters:

parameterContext - the context for the parameter for which an argument should be resolved; never null

extensionContext - the extension context for the Executable about to be invoked; never null

Returns:

true if this resolver can resolve an argument for the parameter

Throws:

ParameterResolutionException

See Also:

• resolveParameter(org.junit.jupiter.api.extension.ParameterContext, org.junit.jupiter.api.extension.ExtensionContext)
• ParameterContext

resolveParameter

@Nullable Object resolveParameter(ParameterContext parameterContext,
 ExtensionContext extensionContext)
                           throws ParameterResolutionException

Resolve an argument for the Parameter in the supplied ParameterContext for the supplied ExtensionContext.

This method is only called by the framework if supportsParameter(org.junit.jupiter.api.extension.ParameterContext, org.junit.jupiter.api.extension.ExtensionContext) previously returned true for the same ParameterContext and ExtensionContext.

The Method or Constructor in which the parameter is declared can be retrieved via ParameterContext.getDeclaringExecutable().

Parameters:

parameterContext - the context for the parameter for which an argument should be resolved; never null

extensionContext - the extension context for the Executable about to be invoked; never null

Returns:

the resolved argument for the parameter; may only be null if the parameter type is not a primitive

Throws:

ParameterResolutionException

See Also:

• supportsParameter(org.junit.jupiter.api.extension.ParameterContext, org.junit.jupiter.api.extension.ExtensionContext)
• ParameterContext