While a serial comma may clarify grouping, it probably is not enough by itself to ensure a binding specification or a clear specification. That is, if you are writing specifications (as suggested by phrase "The tests shall..."), do not depend on commas, which even when used perfectly may be misinterpreted by some readers. Instead, use a labeled or bulleted list, as for example:
The tests shall:
a. verify connectivity,
b. test performance,
c. test endurance by...
If, on the other hand, you are writing an informal description of a process, proper use of commas may allow brief, understandable prose, in contrast to bulky, understandable lists.