In one project, I faced a scenario where a critical feature was failing intermittently. I used logging to capture the state of the application at the time of failure. After analyzing the logs, I identified a race condition in the code. I suggested a code change to introduce a synchronization mechanism, which resolved the issue. This experience reinforced the importance of thorough logging and systematic analysis in debugging.

I prioritize testing tasks based on risk assessment and business impact. I first focus on high-risk areas and critical functionalities that could lead to significant issues if they fail. I also collaborate with the development team to understand the changes and their potential impact. By using this approach, I ensure that the most important aspects are covered, even when time is limited.

To ensure comprehensive test coverage, I start by thoroughly understanding the requirements and the architecture of the system. I then create a detailed test plan that includes unit, integration, system, and acceptance tests. I also use automated testing tools to cover repetitive tasks and regression testing. Additionally, I regularly review and update the test cases to adapt to changes in the system.

When I find a bug, I document it with clear steps to reproduce, expected and actual results, and any relevant logs or screenshots. I then communicate the issue to the developers in a non-confrontational manner, focusing on the problem rather than the person. I also offer suggestions for potential fixes if possible, which helps in the quick resolution of the issue.

Black-box testing involves testing a system without knowledge of its internal workings, focusing on the inputs and outputs. It is used to test functionality from the user's perspective. White-box testing, on the other hand, requires knowledge of the internal code and logic. It involves testing specific code paths and ensuring that the internal operations are performed correctly. Both methods are important for comprehensive testing, each serving different purposes.