An exit criterion is a condition that defines when a test activity has been completed or when a test phase can be concluded. An exit criterion can be based on various factors, such as:

I) Estimates of defect density or reliability measures. These are quantitative measures that indicate how many defects are present in the software product or how likely it is to fail under certain conditions. These can be used as exit criteria to ensure that the software product meets a certain level of quality or performance before moving to the next phase or releasing it to the customer.

III) Accuracy measures, such as code coverage, functionality coverage or risk coverage. These are quantitative measures that indicate how much of the software product has been tested in terms of its code, functionality or risk. These can be used as exit criteria to ensure that the test suite is adequate or complete before moving to the next phase or releasing it to the customer.

IV) Residual risks, such as lack of code coverage in certain areas, unresolved defects or unknown factors. These are qualitative measures that indicate the remaining risks or uncertainties associated with the software product after testing. These can be used as exit criteria to ensure that the residual risks are acceptable or manageable before moving to the next phase or releasing it to the customer. The following factor is not a valid exit criterion:

II) The completion and publication of an exhaustive Test Report. This is not a valid exit criterion, as it does not reflect the quality or completeness of the testing process or product. A test report is a document that summarizes the results and outcomes of a test activity or phase. A test report can be used as an input for deciding whether to exit a test activity or phase, but it is not a condition that defines when to exit. Verified References: A Study Guide to the ISTQB® Foundation Level 2018 Syllabus - Springer, Chapter 2, page 13; Chapter 6, page 58-59.