It’s been a while since I worked with WmUnit but as I recall, when running the tests in Designer, the test runner is local to your machine which calls the services on the IS server. The locale of your Designer environment likely needs to match the locale of the IS instance.
But that’s just a guess on my part. Perhaps others have additional info and may be able to confirm or dismiss that differing locale settings could be the issue.
#unittest#TestFramework#JUNIT#Integration-Server-and-ESB#webMethods