How do you perceive the model of testing divided by levels?

A testing model divided by levels helps structure the software quality assurance process by breaking it into stages with different depths and focuses:

• Unit tests — check individual modules or functions, usually at the code level. Fast and isolated.
• Integration tests — verify interaction between modules or components.
• System tests — test the entire system as a whole, verifying compliance with requirements.
• Acceptance tests — check whether the product meets the expectations and requirements of the customer.

This approach allows for quick detection of errors at early stages, reduces correction costs, and provides more comprehensive coverage of functionality. Each level complements the previous one, ensuring a comprehensive quality check.