Add unit tests

Change-Id: Ic8ad5c8fc6a14d6220bc049400c440bb91732e9e
diff --git a/DESCRIPTION b/DESCRIPTION
index e227ebb..30530fe 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -45,6 +45,7 @@
     utils,
     httr,
     methods,
+    testthat,
     PTXQC
 Collate: 
     'KorAPConnection.R'