test/jdk/java/lang/invoke/VarHandles/describeConstable/DescribeConstableTest.java

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/**
 * @test
 * @bug 8302260
 * @build p.C p.D p.I p.q.Q
 * @run junit DescribeConstableTest
 * @summary Test VarHandle::describeConstable on static fields
 */

import java.lang.constant.ClassDesc;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.invoke.VarHandle;
import java.lang.invoke.VarHandle.VarHandleDesc;
import java.util.stream.Stream;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;
import org.junit.jupiter.params.provider.Arguments;
import static org.junit.jupiter.api.Assertions.*;

public class DescribeConstableTest {
    private static final Lookup LOOKUP = MethodHandles.lookup();
    private static Stream<Arguments> testCases() {
        return Stream.of(
                // static field defined in p.C only
                Arguments.of(p.C.class, "cString", String.class, p.C.class, "CClass"),
                // static fields defined in both superinterface p.I and superclass p.q.Q
                // resolved to the one defined in the direct superinterface of C
                Arguments.of(p.C.class, "stringField", String.class, p.I.class, "I"),
                Arguments.of(p.C.class, "longField", long.class, p.I.class, 10L),
                // static fields defined in superclass p.q.Q only
                Arguments.of(p.C.class, "stringField2", String.class, p.q.Q.class, "QClass2"),
                Arguments.of(p.C.class, "longField2", long.class, p.q.Q.class, 102L),
                // static fields defined in superinterface p.I only
                Arguments.of(p.C.class, "stringField3", String.class, p.I.class, "I3"),
                Arguments.of(p.C.class, "longField3", long.class, p.I.class, 13L),
                // static fields defined in p.D only
                Arguments.of(p.D.class, "dString", String.class, p.D.class, "DClass"),
                Arguments.of(p.D.class, "dLong", long.class, p.D.class, 1L),
                // static fields defined in both superinterface p.I and superclass p.q.Q
                // resolved to the one defined in the direct superinterface of D
                Arguments.of(p.D.class, "stringField", String.class, p.I.class, "I"),
                Arguments.of(p.D.class, "longField", long.class, p.I.class, 10L)
        );
    }

    @ParameterizedTest
    @MethodSource("testCases")
    void test(Class<?> refc, String name, Class<?> type, Class<?> declaringClass, Object value) throws Throwable {
        var vh = LOOKUP.findStaticVarHandle(refc, name, type);
        assertEquals(value, vh.get());

        var refcDesc = refc.describeConstable().orElseThrow();
        var typeDesc = type.describeConstable().orElseThrow();
        var vhd = vh.describeConstable().orElseThrow();
        var vhd2 = VarHandleDesc.ofStaticField(refcDesc, name, typeDesc);

        assertEquals(value, vhd.resolveConstantDesc(LOOKUP).get());
        assertEquals(value, vhd2.resolveConstantDesc(LOOKUP).get());

        assertEquals(vhd.toString(), varHandleDescString(declaringClass, name, type, true));
    }

    static String varHandleDescString(Class<?> declaringClass, String name, Class<?> type, boolean staticField) {
        return String.format("VarHandleDesc[%s%s.%s:%s]",
                             staticField ? "static " : "",
                             declaringClass.describeConstable().orElseThrow().displayName(), name,
                             type.describeConstable().orElseThrow().displayName());
    }
}