test/jdk/java/lang/reflect/Proxy/TestVarArgs.java

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/**
 * @test
 * @bug 8022795
 * @run testng TestVarArgs
 * @summary Verify if a method defined in a proxy interface has ACC_VARARGS set
 */

import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;

import org.testng.annotations.DataProvider;
import org.testng.annotations.Test;
import static org.testng.Assert.*;

public class TestVarArgs {
    interface I {
        Object call(Object... values);
    }
    interface J {
        Object call(Object[] values);
    }

    @DataProvider(name = "proxyInterfaces")
    public Object[][] proxyInterfaces() {
        return new Object[][] {
             { new Class<?>[] { I.class }, true},
             { new Class<?>[] { J.class }, false},
             { new Class<?>[] { I.class, J.class }, true},
             { new Class<?>[] { J.class, I.class }, false},
        };
    }

    @Test(dataProvider = "proxyInterfaces")
    public void testMethod(Class<?>[] proxyInterfaces, boolean isVarArgs) throws Throwable {
        // check if the first proxy interface with the method named "call" declares var result
        Method m = proxyInterfaces[0].getMethod("call", Object[].class);
        assertTrue(m.isVarArgs() == isVarArgs);

        // the method in the generated proxy class should match the method
        // declared in the proxy interface
        Object proxy = Proxy.newProxyInstance(TestVarArgs.class.getClassLoader(),
                                              proxyInterfaces, IH);
        Class<?> proxyClass = proxy.getClass();
        assertTrue(Proxy.isProxyClass(proxyClass));
        Method method = proxyClass.getMethod("call", Object[].class);
        assertTrue(method.isVarArgs() == isVarArgs);

        Object params = new Object[] { "foo", "bar", "goo" };
        Object result;

        // test reflection
        result = method.invoke(proxy, params);
        assertEquals(result, params);

        // test method handle
        MethodHandle mh = MethodHandles.lookup().findVirtual(proxyClass, "call",
                      MethodType.methodType(Object.class, Object[].class));
        assertTrue(mh.isVarargsCollector() == isVarArgs);
        MethodHandle mhVarArity = mh;
        MethodHandle mhFixedArity = mh;
        if (isVarArgs) {
            mhFixedArity = mh.asFixedArity();
        } else {
            mhVarArity = mh.asVarargsCollector(Object[].class);
        }
        result = mhVarArity.invoke(proxy, "foo", "bar", "goo");
        assertEquals(result, params);

        result = mhFixedArity.invoke(proxy, params);
        assertEquals(result, params);

        if (!isVarArgs) {
            MethodType mt = MethodType.methodType(Object.class, Object.class, String.class, String.class, String.class);
            mh = mh.asVarargsCollector(Object[].class).asType(mt);
        }
        result = mh.invoke(proxy, "foo", "bar", "goo");
        assertEquals(result, params);
    }

    private static final InvocationHandler IH = new InvocationHandler() {
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
            return args[0];
        }
    };

}