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/*
* Copyright (c) 2025, 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.
*/
/* @test
* @summary Basic tests for StableSupplier methods
* @enablePreview
* @run junit StableSupplierTest
*/
import org.junit.jupiter.api.Test;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Supplier;
import static org.junit.jupiter.api.Assertions.*;
final class StableSupplierTest {
private static final Supplier<Integer> SUPPLIER = () -> 42;
@Test
void factoryInvariants() {
assertThrows(NullPointerException.class, () -> StableValue.supplier(null));
}
@Test
void basic() {
basic(SUPPLIER);
basic(() -> null);
}
void basic(Supplier<Integer> supplier) {
StableTestUtil.CountingSupplier<Integer> cs = new StableTestUtil.CountingSupplier<>(supplier);
var cached = StableValue.supplier(cs);
assertEquals(".unset", cached.toString());
assertEquals(supplier.get(), cached.get());
assertEquals(1, cs.cnt());
assertEquals(supplier.get(), cached.get());
assertEquals(1, cs.cnt());
assertEquals(Objects.toString(supplier.get()), cached.toString());
}
@Test
void exception() {
StableTestUtil.CountingSupplier<Integer> cs = new StableTestUtil.CountingSupplier<>(() -> {
throw new UnsupportedOperationException();
});
var cached = StableValue.supplier(cs);
assertThrows(UnsupportedOperationException.class, cached::get);
assertEquals(1, cs.cnt());
assertThrows(UnsupportedOperationException.class, cached::get);
assertEquals(2, cs.cnt());
assertEquals(".unset", cached.toString());
}
@Test
void circular() {
final AtomicReference<Supplier<?>> ref = new AtomicReference<>();
Supplier<Supplier<?>> cached = StableValue.supplier(ref::get);
ref.set(cached);
cached.get();
String toString = cached.toString();
assertTrue(toString.startsWith("(this StableSupplier)"));
assertDoesNotThrow(cached::hashCode);
}
@Test
void equality() {
Supplier<Integer> f0 = StableValue.supplier(SUPPLIER);
Supplier<Integer> f1 = StableValue.supplier(SUPPLIER);
// No function is equal to another function
assertNotEquals(f0, f1);
}
@Test
void hashCodeStable() {
Supplier<Integer> f0 = StableValue.supplier(SUPPLIER);
assertEquals(System.identityHashCode(f0), f0.hashCode());
f0.get();
assertEquals(System.identityHashCode(f0), f0.hashCode());
}
}
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