Statistical Analysis of Cryptographic Hashing Algorithms
You simply create a hashed counter.  So output = SHA-256(n) whilst incrementing n. You'd make n a large multi-byte variable, say 16 bytes, and seed it at a random value from some PRNG you find lying around. That way you can perform repeat runs to generate different sequences. I find that you need >10MB for some of the template tests to complete fully.

I won't bother repeating  Natanael's comment to you :-)