Using a CountdownLatch to Test Flows

LatchFunctionalTestCase.java

import org.mule.api.client.MuleClient;
import org.mule.api.context.notification.EndpointMessageNotificationListener;
import org.mule.api.context.notification.ServerNotification;
import org.mule.context.notification.EndpointMessageNotification;
import org.mule.tck.FunctionalTestCase;
import org.mule.util.FileUtils;

import java.io.File;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;


public class LatchFunctionalTestCase extends FunctionalTestCase {

    @Override
    protected String getConfigResources() {
        return "src/main/app/mule-test-config.xml";
    }

    // This latch has a count of one and will be decremented once the file is written
    CountDownLatch fileEndpointHit;

    public void doSetUp() throws Exception {
        fileEndpointHit = new CountDownLatch(1);
        muleContext.registerListener(new EndpointMessageNotificationListener() {
            @Override
            public void onNotification(ServerNotification n) {
                // We're listening here for a notification that the file:outbound-endpoint has finished writing.
                // Once we see it is we countdown the latch.
                EndpointMessageNotification notification = (EndpointMessageNotification) n;
                if (notification.getEndpoint().equals("file:///tmp/foo") && n.getActionName().equals("end dispatch")) {
                    fileEndpointHit.countDown();
                }

            }
        });

    }

    public void testFileCreated() throws Exception {
        MuleClient client = muleContext.getClient();
        client.dispatch("vm://foo", "Hello, world", null);
        // We wait 5 seconds here for the latch to be counted down.
        assertTrue("File hasn't been created", fileEndpointHit.await(5, TimeUnit.SECONDS));
        assertEquals("File content differs from what was dispatched",
                "Hello, world", FileUtils.readFileToString(new File("/tmp/foo/test.txt")));

    }
}

mule-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns="http://www.mulesoft.org/schema/mule/core"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:file="http://www.mulesoft.org/schema/mule/file"
      xmlns:vm="http://www.mulesoft.org/schema/mule/vm"
      xsi:schemaLocation="
        http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/3.2/mule.xsd
        http://www.mulesoft.org/schema/mule/file http://www.mulesoft.org/schema/mule/file/3.2/mule-file.xsd
        http://www.mulesoft.org/schema/mule/vm http://www.mulesoft.org/schema/mule/vm/3.2/mule-vm.xsd
      ">

    <!-- Enable dynamic notification listeners for the ENDPOINT-MESSAGE event.  Note you'll want to disable this
        for production -->
    <notifications dynamic="true">
        <notification event="ENDPOINT-MESSAGE"/>
    </notifications>

    <flow name="file.flow">
        <vm:inbound-endpoint path="foo"/>
        <file:outbound-endpoint path="/tmp/foo" outputPattern="test.txt"/>
    </flow>

</mule>