Intercepting Channels in Tests

HeaderExpectationsTests-context.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:int="http://www.springframework.org/schema/integration"
	xsi:schemaLocation="http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration.xsd
		http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

	<int:channel id="input" />
	
	<int:header-enricher input-channel="input" output-channel="next">
		<int:header name="bar" value="baz"/>
	</int:header-enricher>

	<int:channel id="next" />

	<int:transformer input-channel="next" output-channel="end" expression="'qux'" />
	
	<int:channel id="end">
		<int:queue/>
	</int:channel>

</beans>

HeaderExpectationsTests.java

/*
 * Copyright 2002-2013 the original author or authors.
 *
 * 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.springframework.integration.channel;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;

import java.util.concurrent.atomic.AtomicReference;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.integration.Message;
import org.springframework.integration.MessageChannel;
import org.springframework.integration.channel.interceptor.ChannelInterceptorAdapter;
import org.springframework.integration.core.PollableChannel;
import org.springframework.integration.message.GenericMessage;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

/**
 * @author Gary Russell
 *
 */
@ContextConfiguration
@RunWith(SpringJUnit4ClassRunner.class)
public class HeaderExpectationsTests {

    @Autowired
    private MessageChannel input;

    @Autowired
    private AbstractMessageChannel next;

    @Autowired
    private PollableChannel end;

    @Test
    public void test() {
        final AtomicReference<Message<?>> interceptedMessage = new AtomicReference<Message<?>>();

        // Intercept the channel where we want to test the header(s)
        this.next.addInterceptor(new ChannelInterceptorAdapter() {
            @Override
            public Message<?> preSend(Message<?> message, MessageChannel channel) {
                interceptedMessage.set(message);
                return super.preSend(message, channel);
            }
        });

        input.send(new GenericMessage<String>("foo"));
        Message<?> out = end.receive(1000);
        assertNotNull(out);
        assertEquals("qux", out.getPayload());
        assertNotNull(interceptedMessage.get());
        assertEquals("baz", interceptedMessage.get().getHeaders().get("bar"));
    }
}