diff --git a/db/src/main/java/de/muehlencord/shared/db/CommonAbstractController.java b/db/src/main/java/de/muehlencord/shared/db/CommonAbstractController.java
index 4b0c80b..1f2e76a 100644
--- a/db/src/main/java/de/muehlencord/shared/db/CommonAbstractController.java
+++ b/db/src/main/java/de/muehlencord/shared/db/CommonAbstractController.java
@@ -55,6 +55,11 @@ public abstract class CommonAbstractController {
   @Inject
   @ApplicationPU
   protected EntityManager em;
+  
+  // required for unit testing
+  public void setEntityManager (EntityManager em) {
+    this.em = em;
+  }
 
   @Lock(LockType.READ)
   public <T extends Serializable> T find(Class<T> clazz, Object id) {