Is it necessary for each developer to have a local copy of the database to run unit tests?

Not every developer needs to have a local copy of the database to run unit tests. Usually, unit tests should be isolated from the real database and use mock objects or embedded in-memory databases (for example, H2 for Java). This allows for quick and reliable testing of logic without dependence on external services.

If we are talking about integration tests, then a local copy of the database can be useful, but containers (for example, Docker) with a database or shared testing environments are often used. This approach simplifies setup and reduces the requirements for each developer's local environment.