Both deterministic and non-deterministic have a place

I would divide them as follows:

Unit tests.

These should have deterministic, repeatable tests with the the exact same data every time. Unit tests accompany specific, isolated code sections and should test them in a deterministic fashion.

###Functional and input stress tests.
These can use the non-deterministic approach with the following caveats:

• that fact is clearly delineated and called out
• the random values selected are logged and can be re-tried manually

Both deterministic and non-deterministic have a place

I would divide them as follows:

Unit tests.

These should have deterministic, repeatable tests with the the exact same data every time. Unit tests accompany specific, isolated code sections and should test them in a deterministic fashion.

Functional and input stress tests.

These can use the non-deterministic approach with the following caveats:

• that fact is clearly delineated and called out
• the random values selected are logged and can be re-tried manually