Web services test client
From MoodleDocs
Admins can simulate external access to their own Web Services using the URL http://yourmoodlesite.org/admin/webservice/testclient.php
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Warning: The test client is not clever! It lets you choose disabled/unavaibled functions (however it behaves well and produces an error in these case). This is normal because clients are going to be bad sometimes so we needed to simulate a bad client!