The main function of a test execution tool is to execute predefined test scripts. These tools play a crucial role in automating the repetitive and time-consuming task of running test cases, ensuring consistent and reliable execution to validate the functionality of the software under test.

Test closure activities typically start during the Closure phase of the project. This phase involves wrapping up project activities, including testing. Initiating test closure activities at this point ensures a systematic and organized conclusion to the testing process before the project concludes.

Test strategy provides a high-level view of the testing approach, while the test plan delves into the specifics of test activities, schedules, and resources. The two documents complement each other, with the strategy guiding the overall testing direction and the plan providing detailed implementation steps.

Transitioning to exploratory testing requires a gradual shift in the testing approach. Training the team, gradually implementing exploratory testing alongside scripted testing, and leveraging automation for repetitive tasks can facilitate a smooth transition. It's essential to strike a balance, ensuring that the team gains expertise in exploratory testing while maintaining the stability provided by scripted testing in certain areas.

Resilience testing evaluates how well a system can recover from interruptions, ensuring it maintains functionality even after events like power failures.

Risk Injection is not a step in risk management; instead, it refers to introducing risks intentionally for testing purposes. The actual steps involve identifying risks, analyzing their impact, and implementing strategies for risk mitigation. This systematic approach helps in understanding and addressing potential challenges proactively.

Test Automation Tools are essential in model-based testing as they facilitate the creation and execution of test cases based on the defined models. These tools automate the testing process, ensuring efficiency and accuracy in executing test cases derived from the specified models.

Usability is a key aspect in both functional and non-functional testing. While functional testing validates functionality, non-functional testing ensures aspects like usability, performance, etc.

Selenium Synchronization is a technique that helps manage the timing differences between the test script and the application's behavior. It is crucial for handling dynamic web elements and ensuring the script waits for the expected conditions to be met before proceeding to the next command.

Test coverage refers to the completeness of testing activities, ensuring that the system has been thoroughly tested by covering all identified test scenarios.