Do developers write unit tests on the project?

The practice of writing unit tests depends on the team and project, but in modern professional development, unit tests are considered an important part of the process.

Developers usually write unit tests for:

• verifying the correctness of individual functions and methods,
• preventing regressions when making code changes,
• documenting code behavior through tests.

In mature projects with a good development culture, unit tests cover key business logic and critical modules. In some cases, tests are written simultaneously with the code (TDD).

However, there are projects where, due to deadlines, resource shortages, or technical debt, tests are written sparingly or not at all. In such cases, the role of QA and test automation increases.

Ultimately, the answer depends on the specific project, but ideally, developers should write unit tests as part of their work.