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/*
* Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
import java.util.List;
import java.util.stream.Gatherers;
import java.util.stream.Stream;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;
import static org.junit.jupiter.api.Assertions.*;
import static org.junit.jupiter.api.Assumptions.*;
/**
* @test
* @summary Tests the API and contract of Gatherers.fold
* @run junit GatherersFoldTest
*/
public class GatherersFoldTest {
record Config(int streamSize, boolean parallel) {
Stream<Integer> stream() {
var stream = Stream.iterate(1, i -> i + 1).limit(streamSize);
stream = parallel ? stream.parallel() : stream.sequential();
return stream;
}
}
static final Stream<Integer> sizes(){
return Stream.of(0,1,10,33,99,9999);
}
static final Stream<Config> sequentialAndParallel(int size) {
return Stream.of(false, true)
.map(parallel ->
new Config(size, parallel));
}
static final Stream<Config> configurations() {
return sizes().flatMap(i -> sequentialAndParallel(i));
}
@Test
public void throwsNPEWhenStateSupplierIsNull() {
assertThrows(NullPointerException.class, () -> Gatherers.<String, String>fold(null, (state, next) -> state));
}
@Test
public void throwsNPEWhenFolderFunctionIsNull() {
assertThrows(NullPointerException.class, () -> Gatherers.<String, String>fold(() -> "", null));
}
@ParameterizedTest
@MethodSource("configurations")
public void behavesAsExpected(Config config) {
final var expectedResult = List.of(
config.stream()
.sequential()
.reduce(0L, (acc, next) -> acc + next,(l, r) -> {
throw new IllegalStateException();
})
);
final var result = config.stream()
.gather(Gatherers.fold(() -> 0L, (acc, next) -> acc + next))
.toList();
assertEquals(expectedResult, result);
}
}
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