"The Grade 1 W.O.M.B.A.T. tests whether the sitter would be able to exist safely and effectively within the magical world."
-- J K Rowling's original website
W.O.M.B.A.T. Test – Grade 1
The first W.O.M.B.A.T. test appeared on J K Rowling’s website on March 31, 2006.
The test consisted of questions which required an extensive knowledge of canon and an intuitive understanding of the Wizarding world to answer. A number of the questions required educated guesses, since sufficient information to answer them definitively was not available.
From the Web
The W.O.M.B.A.T. tests reformatted: Reddit.com post