Testing ensures that code behaves as intended by continuously verifying functionality, catching regressions early, and building confidence in changes across a codebase. Establishing a deliberate testing habit helps teams ship faster, collaborate safely, and document product behavior in executable form.
Behavior-Driven Development (BDD) frames tests around user-facing behavior, encouraging readable, scenario-focused specifications. Expect-style assertions power BDD by expressing outcomes in a natural language format—expect(1 + 2).toEqual(3) or expect(add(1, 2)).toBe(3)—so that tests double as documentation.