Problems testing services created with maven-scr-plugin when using pax-exam

Question

I've set up a very simple "HelloWorld" service to demonstrate my problem. It uses the maven-scr-plugin to generate a service descriptor and has a pax-exam unit test. But when I try to run 'mvn clean test' it blocks for a while before giving me this error:

 org.ops4j.pax.swissbox.tracker.ServiceLookupException: gave up waiting for service com.liveops.examples.osgi.helloworld.HelloWorldService

If I run 'mvn -DskipTests=true package' and then run 'mvn test' (without clean) it works. The difference seems to be the addition of this line in my META-INF/M ANIFEST.MF file:

 Service-Component: OSGI-INF/com.liveops.examples.osgi.helloworld.internal.HelloImpl.xml

Does anyone know if there is a way to make sure this line is added earlier in the build process so that 'mvn clean test' will pass? Or is there something else I might be doing wrong?

---

For reference, here is the pom.xml, the service, and the unit test.

    <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.liveops.examples</groupId>
    <artifactId>HelloWorldService</artifactId>
    <version>1.0.0-SNAPSHOT</version>

    <packaging>bundle</packaging>

    <dependencies>
        <dependency>
            <groupId>org.osgi</groupId>
            <artifactId>org.osgi.core</artifactId>
            <version>4.3.1</version>
        </dependency>
        <dependency>
            <groupId>javax.inject</groupId>
            <artifactId>javax.inject</artifactId>
            <version>1</version>
        </dependency>
        <dependency>
            <groupId>org.ops4j.pax.exam</groupId>
            <artifactId>pax-exam</artifactId>
            <version>3.3.0</version>
        </dependency>
        <dependency>
             <groupId>org.ops4j.pax.exam</groupId>
             <artifactId>pax-exam-container-native</artifactId>
             <version>3.3.0</version>
             <scope>test</scope>
         </dependency>
        <dependency>
            <groupId>org.ops4j.pax.exam</groupId>
            <artifactId>pax-exam-junit4</artifactId>
            <version>3.3.0</version>
        </dependency>
        <dependency>
            <groupId>org.ops4j.pax.url</groupId>
            <artifactId>pax-url-aether</artifactId>
            <version>1.6.0</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.ops4j.pax.exam</groupId>
            <artifactId>pax-exam-link-mvn</artifactId>
            <version>3.3.0</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.5.8</version>
        </dependency>
        <dependency>
            <groupId>org.apache.felix</groupId>
            <artifactId>org.apache.felix.framework</artifactId>
            <version>4.0.2</version>
            <scope>test</scope>
        </dependency>     
        <dependency>
            <groupId>org.apache.felix</groupId>
            <artifactId>org.apache.felix.scr.annotations</artifactId>
            <version>1.9.0</version>
        </dependency>
    </dependencies>

    <properties>
        <namespace>com.liveops.examples.osgi.helloworld</namespace>
    </properties>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.0</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>

            <plugin>
                <!--
                 | the following instructions build a simple set of public/private classes into an OSGi bundle
                -->
                <groupId>org.apache.felix</groupId>
                <artifactId>maven-bundle-plugin</artifactId>
                <version>2.3.7</version>
                <extensions>true</extensions>                
                <configuration>
                    <instructions>
                        <Bundle-SymbolicName>${project.name}</Bundle-SymbolicName>
                        <Bundle-Version>${project.version}</Bundle-Version>
                        <!-- Bundle-Activator>${namespace}.internal.HelloActivator</Bundle-Activator -->
                        <!--
                         | assume public classes are in the top package, and private classes are under ".internal"
                        -->
                        <Export-Package>!${namespace}.internal.*,${namespace}.*;version="${project.version}"</Export-Package>
                        <Private-Package>${namespace}.internal.*</Private-Package>
                        <!--
                         | each module can override these defaults in their osgi.bnd file
     -->
                        <!--_include>-osgi.bnd</_include-->
                    </instructions>
                </configuration>   
                <executions>
                    <execution>
                        <id>generate-manifest</id>
                        <phase>process-classes</phase>
                        <goals>
                            <goal>manifest</goal>
                        </goals>
                    </execution>
                </executions>          
            </plugin>
            <plugin>
                <groupId>org.apache.felix</groupId>
                <artifactId>maven-scr-plugin</artifactId>
                <version>1.9.0</version>
                <configuration>
                    <supportedProjectTypes>
                        <supportedProjectType>jar</supportedProjectType>
                        <supportedProjectType>bundle</supportedProjectType>
                        <supportedProjectType>war</supportedProjectType>
                    </supportedProjectTypes>
                    <generateAccessors>true</generateAccessors>
                    <strictMode>true</strictMode>
                    <specVersion>1.1</specVersion>
                    <outputDirectory>target/classes</outputDirectory>
                </configuration>
                <executions>
                    <execution>
                        <id>generate-scr-scrdescriptor</id>
                        <goals>
                            <goal>scr</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

HelloWorld Implementation class

package com.liveops.examples.osgi.helloworld.internal;

import com.liveops.examples.osgi.helloworld.HelloWorldService;
import org.apache.felix.scr.annotations.Service;
import org.apache.felix.scr.annotations.Component;


@Component
@Service(HelloWorldService.class)
public class HelloImpl implements HelloWorldService
{  
    public String helloWorld(String personalization)
    {
        return "Hello " + personalization + "!";
    }
}

The unit test

package com.liveops.examples.osgi.helloworld.internal;

import com.liveops.examples.osgi.helloworld.HelloWorldService;
import junit.framework.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;

import org.ops4j.pax.exam.Option;
import org.ops4j.pax.exam.Configuration;
import org.ops4j.pax.exam.junit.PaxExam;
import org.ops4j.pax.exam.util.PathUtils;

import javax.inject.Inject;

import static org.ops4j.pax.exam.CoreOptions.*;

@RunWith(PaxExam.class)
public class HelloImplTest
{
    @Inject
    HelloWorldService hws;

    @Configuration

    public static Option[] configuration() throws Exception{
            return options(
                    systemProperty("org.ops4j.pax.logging.DefaultServiceLog.level").value("WARN"),
                    mavenBundle("org.apache.felix", "org.apache.felix.scr", "1.6.2"),
                    bundle("reference:file:" + PathUtils.getBaseDir() + "/target/classes"),
                           junitBundles());
    }

    @Test
    public void testInjection()
    {
        Assert.assertNotNull(hws);
    }

    @Test
    public void testHelloWorld() throws Exception
    {
        Assert.assertNotNull(hws);
        Assert.assertEquals("Hello UnitTest!", hws.helloWorld("UnitTest"));

    }
}

Answer 1

Use the ProbeBuilder to enhance your tested bundle:

    @ProbeBuilder
public TestProbeBuilder probeConfiguration(TestProbeBuilder probe) {
    probe.setHeader("Service-Component", "OSGI-INF/com.liveops.examples.osgi.helloworld.internal.HelloImpl.xml");
    return probe;
}

This most likely is all that's missing.

EDIT:

just in case you're trying to use pax-exam in the same bundle you need to take certain actions in your configuration method:

streamBundle(bundle()
.add(SomceClass.class).add("OSGI-INF/com.liveops.examples.osgi.helloworld.internal.HelloImpl.xml", new File("src/main/resources/OSGI-INF/com.liveops.examples.osgi.helloworld.internal.HelloImpl.xml")
.toURL())
.set("Service-Component", "OSGI-INF/com.liveops.examples.osgi.helloworld.internal.HelloImpl.xml")
.build()).start()

a complete sample can be found at here

Answer 2

I may have a fix for this, though it seems a bit in-elegant. I can explicitly add the Service-Component to the maven-bundle-plugin section of the pom file.

    <plugin>
        <groupId>org.apache.felix</groupId>
        <artifactId>maven-bundle-plugin</artifactId>
        <version>2.3.7</version>
        <extensions>true</extensions>                
        <configuration>
            <instructions>
                <Bundle-SymbolicName>${project.name}</Bundle-SymbolicName>
                <Bundle-Version>${project.version}</Bundle-Version>
                <Export-Package>!${namespace}.internal.*,${namespace}.*;version="${project.version}"</Export-Package>
                <Private-Package>${namespace}.internal.*</Private-Package>

                <!--Explicitly add the components no that they can be found in the test phase -->
                <Service-Component>OSGI-INF/com.liveops.examples.osgi.helloworld.internal.HelloImpl.xml</Service-Component>
            </instructions>
        </configuration>   
        <executions>
            <execution>
                <id>generate-manifest</id>
                <phase>process-classes</phase>
                <goals>
                    <goal>manifest</goal>
                </goals>
            </execution>
        </executions>          
    </plugin>

Please let me know if anyone can think of a better way.

Answer 3

The Maven SCR Plugin only generates the service component descriptors but it does not include them in the manifest automatically.

So there's nothing inelegant about including a <Service-Component> instruction in the Maven Bundle Plugin configuration, that's just the documented usage.

Since the manifest header is missing, SCR does not register any services on behalf of your bundle, and that's why Pax Exam can't find the required service.