Module org.junit.jupiter.api

Package org.junit.jupiter.api.extension

Interface TestTemplateInvocationContextProvider

All Superinterfaces:

Extension

@API(status=STABLE,
     since="5.0")
public interface TestTemplateInvocationContextProvider
extends Extension

TestTemplateInvocationContextProvider defines the API for Extensions that wish to provide one or multiple contexts for the invocation of a @TestTemplate method.

This extension point makes it possible to execute a test template in different contexts — for example, with different parameters, by preparing the test class instance differently, or multiple times without modifying the context.

This interface defines two main methods: supportsTestTemplate(org.junit.jupiter.api.extension.ExtensionContext) and provideTestTemplateInvocationContexts(org.junit.jupiter.api.extension.ExtensionContext). The former is called by the framework to determine whether this extension wants to act on a test template that is about to be executed. If so, the latter is called and must return a Stream of TestTemplateInvocationContext instances. Otherwise, this provider is ignored for the execution of the current test template.

A provider that has returned true from its supportsTestTemplate(org.junit.jupiter.api.extension.ExtensionContext) method is called active. When multiple providers are active for a test template method, the Streams returned by their provideTestTemplateInvocationContexts(org.junit.jupiter.api.extension.ExtensionContext) methods will be chained, and the test template method will be invoked using the contexts of all active providers.

An active provider may return zero invocation contexts from its provideTestTemplateInvocationContexts(org.junit.jupiter.api.extension.ExtensionContext) method if it overrides mayReturnZeroTestTemplateInvocationContexts(org.junit.jupiter.api.extension.ExtensionContext) to return true.

Constructor Requirements

Consult the documentation in Extension for details on constructor requirements.

Since:

5.0

See Also:

• TestTemplate
• TestTemplateInvocationContext

Method Summary

Modifier and Type	Method	Description
default boolean	mayReturnZeroTestTemplateInvocationContexts(ExtensionContext context)	Signal that this provider may provide zero invocation contexts in the supplied context.
Stream<TestTemplateInvocationContext>	provideTestTemplateInvocationContexts(ExtensionContext context)	Provide invocation contexts for the test template method represented by the supplied context.
boolean	supportsTestTemplate(ExtensionContext context)	Determine if this provider supports providing invocation contexts for the test template method represented by the supplied context.

Method Details

supportsTestTemplate

boolean supportsTestTemplate(ExtensionContext context)

Determine if this provider supports providing invocation contexts for the test template method represented by the supplied context.

Parameters:

context - the extension context for the test template method about to be invoked; never null

Returns:

true if this provider can provide invocation contexts

See Also:

• provideTestTemplateInvocationContexts(org.junit.jupiter.api.extension.ExtensionContext)
• ExtensionContext

provideTestTemplateInvocationContexts

Stream<TestTemplateInvocationContext> provideTestTemplateInvocationContexts(ExtensionContext context)

Provide invocation contexts for the test template method represented by the supplied context.

This method is only called by the framework if supportsTestTemplate(org.junit.jupiter.api.extension.ExtensionContext) previously returned true for the same ExtensionContext; this method is allowed to return an empty Stream but not null.

The returned Stream will be properly closed by calling BaseStream.close(), making it safe to use a resource such as Files.lines().

Parameters:

context - the extension context for the test template method about to be invoked; never null

Returns:

a Stream of TestTemplateInvocationContext instances for the invocation of the test template method; never null

See Also:

• supportsTestTemplate(org.junit.jupiter.api.extension.ExtensionContext)
• ExtensionContext

mayReturnZeroTestTemplateInvocationContexts

@API(status=EXPERIMENTAL,
     since="5.12")
default boolean mayReturnZeroTestTemplateInvocationContexts(ExtensionContext context)

Signal that this provider may provide zero invocation contexts in the supplied context.

If this method returns false (which is the default) and the provider returns an empty stream from provideTestTemplateInvocationContexts(org.junit.jupiter.api.extension.ExtensionContext), this will be considered an execution error. Override this method to ignore the absence of invocation contexts for this provider.

Parameters:

context - the extension context for the test template method about to be invoked; never null

Returns:

true to allow zero contexts, false to fail execution in case of zero contexts.

Since:

5.12