You have to download the latest version of ejb3unit. Please refer here to download.
There are to different kinds of versions:
Please refer to the Project Dependencies for exact list and version numbers.
If you are using Maven 2 to build your application maven will manage all your download for you.
   <dependencies>
        ...
        <dependency>
             <groupId>com.bm</groupId>
             <artifactId>ejb3unit</artifactId>
             <scope>test</scope>
        </dependency> 
        ...
   </dependencies><profiles>
   <profile>
        <activation>
        <activeByDefault>true</activeByDefault>
        </activation>
        
        <repositories>
                <repository>
                        <snapshots>
                                <enabled>false</enabled>
                        </snapshots>
                        <id>ejb3unit</id>
                        <name>ejb3unit repository</name>
                        <url>http://ejb3unit.sourceforge.net/maven2</url>
                </repository>
        </repositories>
   </profile>
</profiles>