test/jdk/java/lang/Class/getEnclosingMethod/BadEnclosingMethodTest.java

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/*
 * @test
 * @bug 8350704
 * @summary Test behaviors with various bad EnclosingMethod attribute
 * @library /test/lib
 * @run junit BadEnclosingMethodTest
 */

import jdk.test.lib.ByteCodeLoader;
import org.junit.jupiter.api.Test;

import java.lang.classfile.ClassFile;
import java.lang.classfile.attribute.EnclosingMethodAttribute;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Map;
import java.util.Optional;

import static java.lang.constant.ConstantDescs.INIT_NAME;
import static org.junit.jupiter.api.Assertions.*;

class BadEnclosingMethodTest {

    private static Path classPath(String className) {
        return Path.of(System.getProperty("test.classes"), className + ".class");
    }

    /**
     * Loads a test class that is transformed from the Enclosed local class in
     * the Encloser::work method. This local class has its EnclosingMethod
     * attribute transformed to the specific name and type, which may be malformed
     * strings.
     *
     * @param name the new enclosing method name, may be malformed
     * @param type the new enclosing method type, may be malformed
     * @return the loaded test class, for reflective inspection
     */
    private Class<?> loadTestClass(String name, String type) throws Exception {
        var outerName = "Encloser";
        var className = outerName + "$1Enclosed";

        var cf = ClassFile.of();
        var cm = cf.parse(classPath(className));

        var bytes = cf.transformClass(cm, (cb, ce) -> {
            if (ce instanceof EnclosingMethodAttribute em) {
                var cp = cb.constantPool();
                var enclosingMethodName = cp.utf8Entry(name);
                var enclosingMethodType = cp.utf8Entry(type); // a malformed method type
                cb.with(EnclosingMethodAttribute.of(em.enclosingClass(), Optional.of(cp.nameAndTypeEntry(
                        enclosingMethodName, enclosingMethodType
                ))));
            } else {
                cb.with(ce);
            }
        });

        var map = Map.of(
                outerName, Files.readAllBytes(classPath(outerName)),
                className, bytes
        );

        return new ByteCodeLoader(map, BadEnclosingMethodTest.class.getClassLoader())
                .loadClass(className);
    }

    /**
     * Test reflection behaviors when the EnclosingMethod attribute's type is
     * an invalid string.
     */
    @Test
    void testMalformedTypes() throws Exception {
        assertThrows(ClassFormatError.class, () -> loadTestClass("methodName", "(L[;)V"));
        assertThrows(ClassFormatError.class, () -> loadTestClass(INIT_NAME, "(L[;)V"));
    }

    /**
     * Test reflective behaviors when the EnclosingMethod attribute's type is
     * valid, but refers to a class or interface that cannot be found.
     */
    @Test
    void testAbsentMethods() throws Exception {
        var absentMethodType = loadTestClass("methodName", "(Ldoes/not/Exist;)V");
        var ex = assertThrows(TypeNotPresentException.class,
                absentMethodType::getEnclosingMethod);
        assertEquals("does.not.Exist", ex.typeName());

        var absentConstructorType = loadTestClass(INIT_NAME, "(Ldoes/not/Exist;)V");
        ex = assertThrows(TypeNotPresentException.class,
                absentConstructorType::getEnclosingConstructor);
        assertEquals("does.not.Exist", ex.typeName());
    }
}

class Encloser {
    private static void work() {
        class Enclosed {
        }
    }
}