Adding Groovy class to Spring project - spring

Question

I'm trying to add a Groovy class to an existing Spring Java project. I have been following the instructions from two different sources [1] & [2], however, it doesn't seem to work for me.
This is my Groovy class:
package com.example.service;
class MessageService {
String message
}
This is my bean definition:
<?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:lang="http://www.springframework.org/schema/lang"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/lang
http://www.springframework.org/schema/lang/spring-lang-2.5.xsd"
>
<lang:groovy id="messenger" script-source="classpath:com.example.service.MessageService.groovy">
<lang:property name="message" value="This is a Groovy message" />
</lang:groovy>
</beans>
I have added the dependencies as described in the articles to my pom.xml:
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy-all</artifactId>
<version>2.1.8</version>
</dependency>
And updated my plugins:
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
<showDeprecation>true</showDeprecation>
<showWarnings>true</showWarnings>
<compilerId>groovy-eclipse-compiler</compilerId>
<!-- <verbose>false</verbose> -->
</configuration>
<dependencies>
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy-eclipse-compiler</artifactId>
<version>2.8.0-01</version>
</dependency>
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy-eclipse-batch</artifactId>
<version>2.1.8-01</version>
</dependency>
</dependencies>
</plugin>
</plugins>
However, when I run mvn test I can see that the Groovy compiler kicks in and all code "seem" to compile correctly but when the tests are run it goes in a bit of what seems like a loop trying to start the tests several times without throwing a precise error.
Is there anything in my definitions not correct?
[1] http://docs.spring.io/spring/docs/2.5.3/reference/dynamic-language.html
[2] http://groovy.codehaus.org/Groovy-Eclipse+compiler+plugin+for+Maven#Groovy-EclipsecompilerpluginforMaven-WhyanotherGroovycompilerforMavenWhataboutGMaven