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/*
 * @test
 * @run junit/othervm ChainedReflection
 * @summary Test Method::invoke and Constructor::newInstance chained calls that
 *          should wrap NPE in InvocationTargetException properly
 * @comment This test is not using assertThrows given lambdas may affect the
 *          exception stack trace and therefore test anticipations
 */

import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.util.Optional;

import org.junit.jupiter.api.Test;

public class ChainedReflection {

    // This inner class is declared with a constructor that ctorCallMethodInvoke
    // reflects on. Such a constructor cannot be declared in ChainedReflection
    // because JUnit does not allow a test class to declare multiple constructors.
    class Inner {
        Inner() throws ReflectiveOperationException {
            Method m = ChainedReflection.class.getMethod("throwNPE");
            try {
                m.invoke(null);
            } catch (InvocationTargetException e) {
                Throwable t = e.getTargetException();
                if (t instanceof NullPointerException npe) {
                    throw npe;
                } else {
                    throw new RuntimeException("Test failed (InvocationTargetException didn't wrap NullPointerException)");
                }
            } catch (Throwable t) {
                throw new RuntimeException("Test failed (Unexpected exception)", t);
            }
        }
    }

    public static void throwNPE() {
        throw new NullPointerException();
    }

    /*
     * Wrap a NullPointerException with a new NullPointerException
     */
    public static void npe() throws ReflectiveOperationException {
        NullPointerException cause;
        try {
            Optional.of(null);
            throw new RuntimeException("NPE not thrown");
        } catch (NullPointerException e) {
            cause = e;
        }
        Class<?> c = NullPointerException.class;
        Constructor<?> ctor = c.getConstructor();
        NullPointerException npe = (NullPointerException) ctor.newInstance();
        npe.initCause(cause);
        throw npe;
    }

    /**
     * Tests the target method being invoked via core reflection that
     * throws NullPointerException allocated via Constructor::newInstance.
     * The newly allocated NPE thrown by the target method should be
     * wrapped by InvocationTargetException.
     */
    @Test
    public void methodCallNewInstance() throws ReflectiveOperationException {
        Method m = ChainedReflection.class.getMethod("npe");
        try {
            m.invoke(null);
        } catch (InvocationTargetException e) {
            Throwable t = e.getTargetException();
            if (!(t instanceof NullPointerException)) {
                throw new RuntimeException("Test failed (InvocationTargetException didn't wrap NullPointerException)");
            }
        } catch (Throwable t) {
            throw new RuntimeException("Test failed (Unexpected exception)", t);
        }
    }

    /**
     * Tests a constructor C calling the method "throwNPE" that throws
     * a new instance of NullPointerException.
     * C::newInstance should wrap NullPointerException thrown by
     * Method::invoke on "throwNPE"  by InvocationTargetException.
     */
    @Test
    public void ctorCallMethodInvoke() throws ReflectiveOperationException {
        Constructor<?> ctor = ChainedReflection.Inner.class.getDeclaredConstructor(ChainedReflection.class);
        try {
            ctor.newInstance(this);
        } catch (InvocationTargetException e) {
            Throwable t = e.getTargetException();
            if (!(t instanceof NullPointerException)) {
                throw new RuntimeException("Test failed (InvocationTargetException didn't wrap NullPointerException)");
            }
        } catch (Throwable t) {
            throw new RuntimeException("Test failed (Unexpected exception)", t);
        }
    }
}