TestMethods.java

/*
 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

import com.oracle.testlibrary.jsr292.Helper;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Enumeration containing information about methods from
 * {@code j.l.i.MethodHandles} class that are used for testing lambda forms
 * caching.
 *
 * @author kshefov
 */
public enum TestMethods {

    FOLD_ARGUMENTS("foldArguments") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    int modifierMHArgNum = Helper.RNG.nextInt(realArity + 1);
                    data.put("modifierMHArgNum", modifierMHArgNum);
                    Class<?> combinerReturnType;
                    if (realArity == 0) {
                        combinerReturnType = void.class;
                    } else {
                        combinerReturnType = Helper.RNG.nextBoolean() ? void.class : mtTarget.parameterType(0);
                    }
                    data.put("combinerReturnType", combinerReturnType);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    Class<?> combinerReturnType = (Class) data.get("combinerReturnType");
                    int modifierMHArgNum = (int) data.get("modifierMHArgNum");
                    MethodHandle target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                            mtTarget.parameterList(), kind);
                    Class<?> rType = mtTarget.returnType();
                    int combListStart = (combinerReturnType == void.class) ? 0 : 1;
                    if (modifierMHArgNum < combListStart) {
                        modifierMHArgNum = combListStart;
                    }
                    MethodHandle combiner = TestMethods.methodHandleGenerator(combinerReturnType,
                            mtTarget.parameterList().subList(combListStart,
                                    modifierMHArgNum), kind);
                    return MethodHandles.foldArguments(target, combiner);
                }
            },
    DROP_ARGUMENTS("dropArguments") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    int dropArgsPos = Helper.RNG.nextInt(realArity + 1);
                    data.put("dropArgsPos", dropArgsPos);
                    MethodType mtDropArgs = TestMethods.randomMethodTypeGenerator(
                            Helper.RNG.nextInt(Helper.MAX_ARITY - realArity));
                    data.put("mtDropArgs", mtDropArgs);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    MethodType mtDropArgs = (MethodType) data.get("mtDropArgs");
                    int dropArgsPos = (int) data.get("dropArgsPos");
                    MethodHandle target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                            mtTarget.parameterList(), kind);
                    int mtTgtSlotsCount = TestMethods.argSlotsCount(mtTarget);
                    int mtDASlotsCount = TestMethods.argSlotsCount(mtDropArgs);
                    List<Class<?>> fakeParList;
                    if (mtTgtSlotsCount + mtDASlotsCount > Helper.MAX_ARITY - 1) {
                        fakeParList = TestMethods.reduceArgListToSlotsCount(mtDropArgs.parameterList(),
                                Helper.MAX_ARITY - mtTgtSlotsCount - 1);
                    } else {
                        fakeParList = mtDropArgs.parameterList();
                    }
                    return MethodHandles.dropArguments(target, dropArgsPos, fakeParList);
                }
            },
    EXPLICIT_CAST_ARGUMENTS("explicitCastArguments") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY / 2);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    MethodType mtExcplCastArgs = TestMethods.randomMethodTypeGenerator(realArity);
                    if (mtTarget.returnType() == void.class) {
                        mtExcplCastArgs = MethodType.methodType(void.class,
                                mtExcplCastArgs.parameterArray());
                    }
                    if (mtExcplCastArgs.returnType() == void.class) {
                        mtExcplCastArgs = MethodType.methodType(mtTarget.returnType(),
                                mtExcplCastArgs.parameterArray());
                    }
                    data.put("mtExcplCastArgs", mtExcplCastArgs);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    MethodType mtExcplCastArgs = (MethodType) data.get("mtExcplCastArgs");
                    MethodHandle target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                            mtTarget.parameterList(), kind);
                    return MethodHandles.explicitCastArguments(target, mtExcplCastArgs);
                }
            },
    FILTER_ARGUMENTS("filterArguments") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY / 2);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    int filterArgsPos = Helper.RNG.nextInt(realArity + 1);
                    data.put("filterArgsPos", filterArgsPos);
                    int filtersArgsArrayLength = Helper.RNG.nextInt(realArity + 1 - filterArgsPos);
                    data.put("filtersArgsArrayLength", filtersArgsArrayLength);
                    MethodType mtFilter = TestMethods.randomMethodTypeGenerator(filtersArgsArrayLength);
                    data.put("mtFilter", mtFilter);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    MethodType mtFilter = (MethodType) data.get("mtFilter");
                    int filterArgsPos = (int) data.get("filterArgsPos");
                    int filtersArgsArrayLength = (int) data.get("filtersArgsArrayLength");
                    MethodHandle target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                            mtTarget.parameterList(), kind);
                    MethodHandle[] filters = new MethodHandle[filtersArgsArrayLength];
                    for (int i = 0; i < filtersArgsArrayLength; i++) {
                        filters[i] = TestMethods.filterGenerator(mtFilter.parameterType(i),
                                mtTarget.parameterType(filterArgsPos + i), kind);
                    }
                    return MethodHandles.filterArguments(target, filterArgsPos, filters);
                }
            },
    FILTER_RETURN_VALUE("filterReturnValue") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    int filterArgsPos = Helper.RNG.nextInt(realArity + 1);
                    int filtersArgsArrayLength = Helper.RNG.nextInt(realArity + 1 - filterArgsPos);
                    MethodType mtFilter = TestMethods.randomMethodTypeGenerator(filtersArgsArrayLength);
                    data.put("mtFilter", mtFilter);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    MethodType mtFilter = (MethodType) data.get("mtFilter");
                    MethodHandle target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                            mtTarget.parameterList(), kind);
                    MethodHandle filter = TestMethods.filterGenerator(mtTarget.returnType(),
                            mtFilter.returnType(), kind);
                    return MethodHandles.filterReturnValue(target, filter);
                }
            },
    INSERT_ARGUMENTS("insertArguments") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    int insertArgsPos = Helper.RNG.nextInt(realArity + 1);
                    data.put("insertArgsPos", insertArgsPos);
                    int insertArgsArrayLength = Helper.RNG.nextInt(realArity + 1 - insertArgsPos);
                    MethodType mtInsertArgs = MethodType.methodType(void.class, mtTarget.parameterList()
                            .subList(insertArgsPos, insertArgsPos + insertArgsArrayLength));
                    data.put("mtInsertArgs", mtInsertArgs);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    MethodType mtInsertArgs = (MethodType) data.get("mtInsertArgs");
                    int insertArgsPos = (int) data.get("insertArgsPos");
                    MethodHandle target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                            mtTarget.parameterList(), kind);
                    Object[] insertList = Helper.randomArgs(mtInsertArgs.parameterList());
                    return MethodHandles.insertArguments(target, insertArgsPos, insertList);
                }
            },
    PERMUTE_ARGUMENTS("permuteArguments") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY / 2);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    int[] permuteArgsReorderArray = new int[realArity];
                    int mtParmuteArgsNum = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    mtParmuteArgsNum = mtParmuteArgsNum == 0 ? 1 : mtParmuteArgsNum;
                    MethodType mtPermuteArgs = TestMethods.randomMethodTypeGenerator(mtParmuteArgsNum);
                    mtTarget = mtTarget.changeReturnType(mtPermuteArgs.returnType());
                    for (int i = 0; i < realArity; i++) {
                        int mtPermuteArgsParNum = Helper.RNG.nextInt(mtPermuteArgs.parameterCount());
                        permuteArgsReorderArray[i] = mtPermuteArgsParNum;
                        mtTarget = mtTarget.changeParameterType(
                                i, mtPermuteArgs.parameterType(mtPermuteArgsParNum));
                    }
                    data.put("mtTarget", mtTarget);
                    data.put("permuteArgsReorderArray", permuteArgsReorderArray);
                    data.put("mtPermuteArgs", mtPermuteArgs);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    MethodType mtPermuteArgs = (MethodType) data.get("mtPermuteArgs");
                    int[] permuteArgsReorderArray = (int[]) data.get("permuteArgsReorderArray");
                    MethodHandle target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                            mtTarget.parameterList(), kind);
                    return MethodHandles.permuteArguments(target, mtPermuteArgs, permuteArgsReorderArray);
                }
            },
    THROW_EXCEPTION("throwException") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    Class<?> rType = mtTarget.returnType();
                    return MethodHandles.throwException(rType, Exception.class
                    );
                }
            },
    GUARD_WITH_TEST("guardWithTest") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    int modifierMHArgNum = Helper.RNG.nextInt(realArity + 1);
                    data.put("modifierMHArgNum", modifierMHArgNum);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    int modifierMHArgNum = (int) data.get("modifierMHArgNum");
                    TestMethods.Kind targetKind;
                    TestMethods.Kind fallbackKind;
                    if (kind.equals(TestMethods.Kind.ONE)) {
                        targetKind = TestMethods.Kind.ONE;
                        fallbackKind = TestMethods.Kind.TWO;
                    } else {
                        targetKind = TestMethods.Kind.TWO;
                        fallbackKind = TestMethods.Kind.ONE;
                    }
                    MethodHandle target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                            mtTarget.parameterList(), targetKind);
                    MethodHandle fallback = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                            mtTarget.parameterList(), fallbackKind);
                    MethodHandle test = TestMethods.methodHandleGenerator(boolean.class,
                            mtTarget.parameterList().subList(0, modifierMHArgNum), kind);
                    return MethodHandles.guardWithTest(test, target, fallback);
                }
            },
    CATCH_EXCEPTION("catchException") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    int modifierMHArgNum = Helper.RNG.nextInt(realArity + 1);
                    data.put("modifierMHArgNum", modifierMHArgNum);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    int modifierMHArgNum = (int) data.get("modifierMHArgNum");
                    MethodHandle target;
                    if (kind.equals(TestMethods.Kind.ONE)) {
                        target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                                mtTarget.parameterList(), TestMethods.Kind.ONE);
                    } else {
                        target = TestMethods.methodHandleGenerator(mtTarget.returnType(),
                                mtTarget.parameterList(), TestMethods.Kind.EXCEPT);
                    }
                    List<Class<?>> handlerParamList = new ArrayList<>(mtTarget.parameterCount() + 1);
                    handlerParamList.add(Exception.class);
                    handlerParamList.addAll(mtTarget.parameterList().subList(0, modifierMHArgNum));
                    MethodHandle handler = TestMethods.methodHandleGenerator(
                            mtTarget.returnType(), handlerParamList, TestMethods.Kind.TWO);
                    return MethodHandles.catchException(target, Exception.class, handler);
                }
            },
    INVOKER("invoker") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    return MethodHandles.invoker(mtTarget);
                }
            },
    EXACT_INVOKER("exactInvoker") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    return MethodHandles.exactInvoker(mtTarget);
                }
            },
    SPREAD_INVOKER("spreadInvoker") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    // Arity after reducing because of long and double take 2 slots.
                    int realArity = mtTarget.parameterCount();
                    int modifierMHArgNum = Helper.RNG.nextInt(realArity + 1);
                    data.put("modifierMHArgNum", modifierMHArgNum);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    int modifierMHArgNum = (int) data.get("modifierMHArgNum");
                    return MethodHandles.spreadInvoker(mtTarget, modifierMHArgNum);
                }
            },
    ARRAY_ELEMENT_GETTER("arrayElementGetter") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    Class<?> rType = mtTarget.returnType();
                    if (rType == void.class) {
                        rType = Object.class;
                    }
                    return MethodHandles.arrayElementGetter(Array.newInstance(rType, 2).getClass());
                }
            },
    ARRAY_ELEMENT_SETTER("arrayElementSetter") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    Class<?> rType = mtTarget.returnType();
                    if (rType == void.class) {
                        rType = Object.class;
                    }
                    return MethodHandles.arrayElementSetter(Array.newInstance(rType, 2).getClass());
                }
            },
    CONSTANT("constant") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    Class<?> rType = mtTarget.returnType();
                    if (rType == void.class) {
                        rType = Object.class;
                    }
                    if (rType.equals(boolean.class)) {
                        // There should be the same return values because for default values there are special "zero" forms
                        return MethodHandles.constant(rType, true);
                    } else {
                        return MethodHandles.constant(rType, kind.getValue(rType));
                    }
                }
            },
    IDENTITY("identity") {
                @Override
                public Map<String, Object> getTestCaseData() {
                    Map<String, Object> data = new HashMap<>();
                    int desiredArity = Helper.RNG.nextInt(Helper.MAX_ARITY);
                    MethodType mtTarget = TestMethods.randomMethodTypeGenerator(desiredArity);
                    data.put("mtTarget", mtTarget);
                    return data;
                }

                @Override
                protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) {
                    MethodType mtTarget = (MethodType) data.get("mtTarget");
                    Class<?> rType = mtTarget.returnType();
                    if (rType == void.class) {
                        rType = Object.class;
                    }
                    return MethodHandles.identity(rType);
                }
            };

    /**
     * Test method's name.
     */
    public final String name;

    private TestMethods(String name) {
        this.name = name;
    }

    protected MethodHandle getMH(Map<String, Object> data, TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
        throw new UnsupportedOperationException("TESTBUG: getMH method is not implemented for test method " + this);
    }

    /**
     * Creates an adapter method handle depending on a test method from
     * MethodHandles class. Adapter is what is returned by the test method. This
     * method is able to create two kinds of adapters, their type will be the
     * same, but return values are different.
     *
     * @param data a Map containing data to create a method handle, can be
     * obtained by {@link #getTestCaseData} method
     * @param kind defines whether adapter ONE or adapter TWO will be
     * initialized. Should be equal to TestMethods.Kind.ONE or
     * TestMethods.Kind.TWO
     * @return Method handle adapter that behaves according to
     * TestMethods.Kind.ONE or TestMethods.Kind.TWO
     * @throws java.lang.NoSuchMethodException
     * @throws java.lang.IllegalAccessException
     */
    public MethodHandle getTestCaseMH(Map<String, Object> data, TestMethods.Kind kind)
            throws NoSuchMethodException, IllegalAccessException {
        if (data == null) {
            throw new Error(String.format("TESTBUG: Data for test method %s is not prepared",
                    this.name));
        }
        if (!kind.equals(TestMethods.Kind.ONE) && !kind.equals(TestMethods.Kind.TWO)) {
            throw new IllegalArgumentException("TESTBUG: Wrong \"kind\" (" + kind
                    + ") arg to getTestCaseMH function."
                    + " Should be Kind.ONE or Kind.TWO");
        }
        return getMH(data, kind);
    }

    /**
     * Returns a data Map needed for {@link #getTestCaseMH} method.
     *
     * @return data Map needed for {@link #getTestCaseMH} method
     */
    public Map<String, Object> getTestCaseData() {
        throw new UnsupportedOperationException(
                "TESTBUG: getTestCaseData method is not implemented for test method " + this);
    }

    /**
     * Enumeration used in methodHandleGenerator to define whether a MH returned
     * by this method returns "2" in different type representations, "4", or
     * throw an Exception.
     */
    public static enum Kind {

        ONE(2),
        TWO(4),
        EXCEPT(0);

        private final int value;

        private Object getValue(Class<?> cl) {
            return Helper.castToWrapper(value, cl);
        }

        private MethodHandle getBasicMH(Class<?> rType) throws NoSuchMethodException, IllegalAccessException {
            MethodHandle result = null;
            switch (this) {
                case ONE:
                case TWO:
                    if (rType.equals(void.class)) {
                        result = MethodHandles.lookup().findVirtual(Kind.class, "returnVoid", MethodType.methodType(void.class));
                        result = MethodHandles.insertArguments(result, 0, this);
                    } else {
                        result = MethodHandles.constant(rType, getValue(rType));
                    }
                    break;
                case EXCEPT:
                    result = MethodHandles.throwException(rType, Exception.class);
                    result = MethodHandles.insertArguments(result, 0, new Exception());
                    break;
            }
            return result;
        }

        private void returnVoid() {
        }

        private Kind(int value) {
            this.value = value;
        }
    }

    /**
     * Routine used to obtain a randomly generated method type.
     *
     * @param arity Arity of returned method type.
     * @return MethodType generated randomly.
     */
    private static MethodType randomMethodTypeGenerator(int arity) {
        final Class<?>[] CLASSES = {
            Object.class,
            int.class,
            boolean.class,
            byte.class,
            short.class,
            char.class,
            long.class,
            float.class,
            double.class
        };
        if (arity > Helper.MAX_ARITY) {
            throw new IllegalArgumentException(
                    String.format("Arity should not exceed %d!", Helper.MAX_ARITY));
        }
        List<Class<?>> list = Helper.randomClasses(CLASSES, arity);
        list = Helper.getParams(list, false, arity);
        int i = Helper.RNG.nextInt(CLASSES.length + 1);
        Class<?> rtype = i == CLASSES.length ? void.class : CLASSES[i];
        return MethodType.methodType(rtype, list);
    }

    /**
     * Routine used to obtain a method handles of a given type an kind (return
     * value).
     *
     * @param returnType Type of MH return value.
     * @param argTypes Types of MH args.
     * @param kind Defines whether the obtained MH returns "1" or "2".
     * @return Method handle of the given type.
     * @throws NoSuchMethodException
     * @throws IllegalAccessException
     */
    private static MethodHandle methodHandleGenerator(Class<?> returnType,
            List<Class<?>> argTypes, TestMethods.Kind kind)
            throws NoSuchMethodException, IllegalAccessException {
        MethodHandle result;
        result = kind.getBasicMH(returnType);
        return Helper.addTrailingArgs(result, argTypes.size(), argTypes);
    }

    /**
     * Routine that generates filter method handles to test
     * MethodHandles.filterArguments method.
     *
     * @param inputType Filter's argument type.
     * @param returnType Filter's return type.
     * @param kind Filter's return value definer.
     * @return A filter method handle, that takes one argument.
     * @throws NoSuchMethodException
     * @throws IllegalAccessException
     */
    private static MethodHandle filterGenerator(Class<?> inputType, Class<?> returnType,
            TestMethods.Kind kind) throws NoSuchMethodException, IllegalAccessException {
        MethodHandle tmpMH = kind.getBasicMH(returnType);
        if (inputType.equals(void.class)) {
            return tmpMH;
        }
        ArrayList<Class<?>> inputTypeList = new ArrayList<>(1);
        inputTypeList.add(inputType);
        return Helper.addTrailingArgs(tmpMH, 1, inputTypeList);
    }

    private static int argSlotsCount(MethodType mt) {
        int result = 0;
        for (Class cl : mt.parameterArray()) {
            if (cl.equals(long.class) || cl.equals(double.class)) {
                result += 2;
            } else {
                result++;
            }
        }
        return result;
    }

    private static List<Class<?>> reduceArgListToSlotsCount(List<Class<?>> list,
            int desiredSlotCount) {
        List<Class<?>> result = new ArrayList<>(desiredSlotCount);
        int count = 0;
        for (Class<?> cl : list) {
            if (count >= desiredSlotCount) {
                break;
            }
            if (cl.equals(long.class) || cl.equals(double.class)) {
                count += 2;
            } else {
                count++;
            }
            result.add(cl);
        }
        return result;
    }
}