src/main/java/org/apache/sling/junit/rules/TeleporterRule.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.sling.junit.rules;

import org.apache.sling.junit.Activator;
import org.junit.rules.ExternalResource;

/** JUnit Rule used to teleport a server-side test to a Sling instance
 *  to execute it there. See the launchpad/integration-tests module for
 *  usage examples (coming soon). 
 *  A concrete TeleporterRule class is selected to match the different required 
 *  behaviors of the server-side and client-side variants of this rule.
 *  The junit.core module only contains the server-side code, to minimize
 *  its dependencies, and the client-side part is in the sling testing.teleporter
 *  module.  
 */
public abstract class TeleporterRule extends ExternalResource {
    protected Class<?> classUnderTest;

    /** Name of the implementation class to use by default when running on the client side */ 
    public static final String DEFAULT_CLIENT_CLASS = "org.apache.sling.testing.teleporter.client.ClientSideTeleporter";
    
    protected TeleporterRule() {
    }
    
    private void setClassUnderTest(Class<?> c) {
        this.classUnderTest = c;
    }
    
    /** Build a TeleporterRule for the given class, using the default
     *  client class name.
     */
    public static TeleporterRule forClass(Class <?> classUnderTest) {
        return forClass(classUnderTest, null);
    }
    
    /** Build a TeleporterRule for the given class, optionally using
     *  a specific client class.
     */
    public static TeleporterRule forClass(Class <?> classUnderTest, String clientTeleporterClassName) {
        TeleporterRule result = null;
        
        if(Activator.getBundleContext() != null) {
            // We're running on the server side
            result = new ServerSideTeleporter();
        } else {
            // Client-side. Instantiate the class dynamically to 
            // avoid bringing its dependencies into this module when
            // it's running on the server side
            final String clientClass = clientTeleporterClassName == null ? DEFAULT_CLIENT_CLASS : clientTeleporterClassName;
            try {
                result = (TeleporterRule)(TeleporterRule.class.getClassLoader().loadClass(clientClass).newInstance());
            } catch(Exception e) {
                throw new RuntimeException("Unable to instantiate Teleporter client " + clientClass, e);
            }
        }
        
        result.setClassUnderTest(classUnderTest);
        return result;
    }
    
    /** If running on the server side, get an OSGi service */
    public final <T> T getService (Class<T> serviceClass) {
        return getService(serviceClass, null);
    }
    
    /** If running on the server side, get an OSGi service specified by an LDAP service filter */
    public <T> T getService (Class<T> serviceClass, String ldapFilter) {
        throw new UnsupportedOperationException("This TeleporterRule does not implement getService()");
    }
}