/**
 *
 * Copyright 2020 Florian Schmaus
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.jivesoftware.smack.test.util;

import java.lang.reflect.Field;

import org.apache.commons.lang3.reflect.FieldUtils;

public class Whitebox {

    public static <T> T getInternalState(Object object, String fieldName, Class<T> fieldType) {
        Class<?> objectClass = object.getClass();

        Field field = FieldUtils.getField(objectClass, fieldName, true);

        Object res;
        try {
            res = field.get(object);
        } catch (IllegalArgumentException | IllegalAccessException e) {
            throw new AssertionError(e);
        }

        if (!fieldType.isInstance(res)) {
            throw new AssertionError(res + " is not a (sub)type of " + fieldType);
        }

        return fieldType.cast(res);
    }

}