Royce 1970 diagram 8 shows the testing process.
(Double-click to enlarge)
The comments of Royce70 Diagram 5 apply here. Although, the large area devoted to testing is here maybe appropriate, given that "Without question the biggest user of project resources, whether it be manpower, computer time, or management judgment, is the test phase. It is the phase of greatest risk in terms of dollars and schedule." Making it *loom* is appropriate.