You can only test statistical randomness anyway, and that does not prove whether the number sequence is cryptographically strong. Statistically testing a PRNG requires quite a lot (10 or even 100Gbytes) of the generated bits.
Dieharder is a very good testing suite.
http://www.phy.duke.edu/~rgb/General/dieharder.php
And TestU01 is also well-known.
http://www.iro.umontreal.ca/~simardr/testu01/tu01.html