During which phase of the software testing lifecycle are test cases actively run?

Test execution is the phase of the software testing lifecycle where test cases are actively run. This phase is critical because it involves executing the defined test cases against the software build to verify that it meets the specified requirements. During this phase, testers execute both automated and manual test cases, observe the outcomes, and document any discrepancies between the expected and actual results.

The importance of this phase lies in its role in identifying defects or issues within the software, ensuring that any problems are found and addressed before release. Test execution leads to valuable feedback that can be used for further improvements and adjustments in the software.

In contrast, the other phases such as test design involve creating the test cases based on requirements, test planning focuses on defining the scope and objectives of testing, and test closure is concerned with finalizing the testing process and reporting findings, rather than actively running tests. Each of these phases is essential in the overall testing process, but only during test execution are the test cases actively carried out.