Test Inspected Unit or Inspect Unit Tested Code?

Code inspection and unit testing are two popular fault- detecting techniques at unit level. Organizations where inspections are done generally supplement it with unit testing, as both are complementary. A natural question is the order in which the two techniques should be exercised as this may impact the overall effectiveness and efficiency of the verification process. In this paper, we present a controlled experiment comparing the two execution-orders, namely, code inspection followed by unit testing (CI-UT) and unit testing followed by code inspection (UT-CI), performed by a group of fresh software engineers in a company. The subjects inspected program-units by traversing a set of usage scenarios and applied unit testing by writing JUnit tests for the same. Our results showed that unit testing can be more effective, as well as more efficient, if applied after code inspection whereas the later is unaffected of the execution- order. Overall results suggest that sequence CI-UT performs better than UT-CI in time-constrained situations.