How do you understand that testing is complete and sufficiently tested?

Determine that testing is complete and sufficient based on several criteria:

• Requirements coverage: all functional and non-functional requirements are tested.
• Code coverage: the required level of coverage (unit, integration) is achieved.
• Absence of critical defects: found bugs are fixed, no blocking issues.
• Test stability: tests pass reliably without random failures.
• Time and resources: the allocated budget and testing deadlines are exhausted.
• Risks: remaining risks are assessed and accepted by stakeholders.

Testing is considered complete when there is a balance between product quality and testing costs, and all key risks are minimized.