The answer depends on what is 'testing'?

The minimum requirement for starting testing would be a Functional Requirement sSpecifications (FRS), aka Business Requirements Document. I would start testing by reviewing this document.

If testing means functional testing, then I would need

1. BRD/FRS as mentioned earlier

2. All written test cases for the feature(s) decided to be tested

3. A build form development that 

  a. compiles, installs and runs without major errors (in other words, passes sanity/smoke testing)

  b. contains the functionality being tested.