The Testament is categorized as a legal-suspense thriller. Typically, these have three distinguishing features. First, their protagonists tend to be figures within the legal profession and are featured in courtroom scenes with high drama and high stakes. Second, their plots revolve around a mystery to be solved and include unexpected twists that keep the reader in a state of tension and suspense. Finally, they conclude with justice being served or vengeance being exacted.

The Testament both fulfils and deviates from these expectations. The main protagonist, Nate O’Riley, is a litigator, and toward the end of the novel, he is depicted practicing his craft. The plot revolves around several mysteries, including whether Rachel Lane will be found and what she will do with her inheritance, whether her siblings will succeed in challenging their father’s will, and whether Nate will survive his bout with dengue fever. The stakes are high and, in Nate’s case, life-threatening, and justice is served at the end of the novel.

What distinguishes The Testament from other legal thrillers is the execution of these stock elements. Though a litigator, Nate is ready to leave his profession behind. His scenes deposing witnesses are relatively low stakes in that they are pre-trial depositions.