MethodHandlesArityLimitsTest.java

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/* @test
 * @summary unit tests for arity limits of methods in java.lang.invoke.MethodHandles
 * @run junit/othervm test.java.lang.invoke.MethodHandlesArityLimitsTest
 **/

package test.java.lang.invoke;

import org.junit.*;

import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.WrongMethodTypeException;
import java.lang.invoke.MethodType;
import java.lang.invoke.VarHandle;
import java.util.List;

import java.util.stream.IntStream;

import static org.junit.Assert.*;

public class MethodHandlesArityLimitsTest {

    private static MethodType mt254 = null;
    private static MethodType mt255 = null;

    static {
        Class<?>[] classes254 = IntStream.range(0, 254)
                                         .mapToObj(i -> int.class)
                                         .toArray(Class[]::new);
        mt254 = MethodType.methodType(void.class, classes254);
        mt255 = mt254.appendParameterTypes(int.class);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testDropArgumentsToMatch() {
        MethodHandles.dropArgumentsToMatch(MethodHandles.empty(mt254), 0, mt255.parameterList(), 0);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testEmpty() {
        MethodHandles.empty(mt255);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testExplicitCastArguments() {
        MethodHandles.explicitCastArguments(
                                         MethodHandles.empty(mt254),
                                         mt254.dropParameterTypes(0, 1).insertParameterTypes(0, long.class) );
    }

    @Test(expected = IllegalArgumentException.class)
    public void testPermuteArguments() {
        MethodHandles.permuteArguments(
                                    MethodHandles.empty(MethodType.methodType(void.class)),
                                    mt255);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testVarHandleInvoker() {
        MethodHandles.varHandleInvoker(VarHandle.AccessMode.GET, mt254);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testVarHandleExactInvoker() {
        MethodHandles.varHandleExactInvoker(VarHandle.AccessMode.GET, mt254);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testMHExactInvoker() {
        MethodHandles.exactInvoker(mt255);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testMHInvoker() {
        MethodHandles.invoker(mt255);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testMHSpreadInvoker() {
        MethodHandles.spreadInvoker(mt255, 255);
    }

    @Test(expected = WrongMethodTypeException.class)
    public void testAsType() throws ReflectiveOperationException {
        MethodHandle asList = MethodHandles.lookup().findStatic(
                                                java.util.Arrays.class,
                                                "asList",
                                                MethodType.methodType(List.class, Object[].class));
        try {
           asList.asType(MethodType.genericMethodType(254));//does not throw IAE or WMTE
        }
        catch(WrongMethodTypeException wmte) {
           throw new AssertionError("Unexpected WrongMethodTypeException thrown", wmte);
        }
        asList.asType(MethodType.genericMethodType(255));//throws WMTE
    }
}