test/unit/org/apache/cassandra/config/OverrideConfigurationLoader.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.cassandra.config;

import java.util.function.Consumer;
import java.util.function.Function;

import org.apache.cassandra.exceptions.ConfigurationException;

/**
 * Helper class for programmatically overriding individual config values before DatabaseDescriptor is bootstrapped.
 */
public class OverrideConfigurationLoader implements ConfigurationLoader
{

    private static Consumer<Config> configModifier;

    public Config loadConfig() throws ConfigurationException
    {
        YamlConfigurationLoader loader = new YamlConfigurationLoader();
        Config config = loader.loadConfig();
        configModifier.accept(config);
        return config;
    }

    public static void override(Consumer<Config> modifier)
    {
        System.setProperty(Config.PROPERTY_PREFIX + "config.loader", OverrideConfigurationLoader.class.getName());
        configModifier = modifier;
    }
}