What problems can arise if you only pay attention to test coverage?

• Overconfidence: High test coverage does not guarantee correct software operation in real conditions, as tests may not cover all boundary cases and usage scenarios.
• Testing only syntax: Tests may only verify syntactical correctness, but not functionality and business logic.
• Tests on unused code: A high coverage percentage may include tests for unused or outdated code sections.
• Lack of performance and security testing: Test coverage usually does not include performance, scalability, and security vulnerability checks.
• Maintaining false tests: Presence of tests that always pass due to incorrect logic or data.
• Poorly structured tests: Tests can be complex, unreadable, and dependent on each other.

Having high test coverage is important, but it should be considered as one of many quality indicators of software. Attention should also be paid to:

• Quality of tests themselves: Are tests written to verify functionality, boundary conditions, negative scenarios?
• Types of tests: Use of different test types (unit, integration, functional, end-to-end, load, etc.).
• Test automation: Degree of automation in testing processes.
• Test execution regularity: Frequency and stability of tests in the CI/CD process.
• Manual testing: The necessity of manual testing at certain stages.
• Test result analysis: Understanding reasons for test failures and their prompt resolution.
• User feedback: Considering real usage scenarios and errors found by users.