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/*
* Copyright 2015-2018 the original author or authors.
*
* All rights reserved. This program and the accompanying materials are
* made available under the terms of the Eclipse Public License v2.0 which
* accompanies this distribution and is available at
*
* http://www.eclipse.org/legal/epl-v20.html
*/
package org.junit.jupiter.api.function;
import static org.apiguardian.api.API.Status.STABLE;
import org.apiguardian.api.API;
/**
* {@code ThrowingSupplier} is a functional interface that can be used to
* implement any generic block of code that returns an object and
* potentially throws a {@link Throwable}.
*
* The {@code ThrowingSupplier} interface is similar to
* {@link java.util.function.Supplier}, except that a {@code ThrowingSupplier}
* can throw any kind of exception, including checked exceptions.
*
*
As of JUnit Jupiter 5.3, {@code ThrowingSupplier} extends
* {@link Executable}, providing a default implementation of
* {@link #execute()} that delegates to {@link #get()} and ignores the return
* value. This allows the Java compiler to disambiguate between
* {@code ThrowingSupplier} and {@code Executable} when performing type
* inference for a lambda expression or method reference supplied to
* an overloaded method that accepts either a {@code ThrowingSupplier} or an
* {@code Executable}.
*
*
Rationale for throwing {@code Throwable} instead of {@code Exception}
*
* Although Java applications typically throw exceptions that are instances
* of {@link Exception}, {@link RuntimeException},
* {@link Error}, or {@link AssertionError} (in testing
* scenarios), there may be use cases where a {@code ThrowingSupplier} needs to
* explicitly throw a {@code Throwable}. In order to support such specialized
* use cases, {@link #get} is declared to throw {@code Throwable}.
*
* @since 5.0
* @param the type of argument supplied
* @see java.util.function.Supplier
* @see org.junit.jupiter.api.Assertions#assertTimeout(java.time.Duration, ThrowingSupplier)
* @see org.junit.jupiter.api.Assertions#assertTimeoutPreemptively(java.time.Duration, ThrowingSupplier)
* @see Executable
* @see ThrowingConsumer
*/
@FunctionalInterface
@API(status = STABLE, since = "5.0")
public interface ThrowingSupplier extends Executable {
/**
* Delegates to {@link #get()} and ignores the return value.
*
* This default method is not intended to be overridden. See
* {@linkplain ThrowingSupplier class-level documentation} for further
* details.
*
* @since 5.3
* @see #get()
*/
@Override
@API(status = STABLE, since = "5.3")
default void execute() throws Throwable {
get();
}
/**
* Get a result, potentially throwing an exception.
*
* @return a result
*/
T get() throws Throwable;
}