unit testing

hi,

i have a doubt in unit testing.

How can check my table ,its have all the fields ...like that.

for ex.

Initially i have four fields ..
it works
if suppose
    i am adding another two fields in my form but i amn't mention in
the database.

if i am verified that (model)in unit testing .. i have to check..
that extra fields there or not.

how to check that

pls help me