Testing, Quality & Reliability Topics
Quality assurance, testing methodologies, test automation, and reliability engineering. Includes QA frameworks, accessibility testing, quality metrics, and incident response from a reliability/engineering perspective. Covers testing strategies, risk-based testing, test case development, UAT, and quality transformations. Excludes operational incident management at scale (see 'Enterprise Operations & Incident Management').
Testing and Validation
Candidates should demonstrate a systematic approach to testing and validating user interface code and interactions. Coverage should include designing manual and automated test cases for edge conditions such as null values, empty collections, single element inputs, duplicate entries, negative numbers, and boundary indices. Candidates should be able to reason through test cases, verify correctness, and explain trade offs between unit tests and integration tests. For component work, candidates should show familiarity with writing automated tests that verify behavior and user interactions rather than implementation details, including testing asynchronous flows, loading and error states, and common mocking strategies. Familiarity with common front end testing tools and libraries and an ability to explain test strategy, test maintenance, and regression testing practices are important.
Testing Strategy and Coverage
Assess the adequacy quality and coverage of tests for features and systems. Candidates should be able to discuss unit tests for business logic component level tests integration tests accessibility testing and end to end tests for critical flows. The focus is on testing behavior rather than implementation details identifying gaps in coverage for high risk areas proposing targeted tests for edge conditions and explaining trade offs between test coverage and development velocity. Topics also include mocking strategies test data management continuous integration testing pipelines and metrics used to measure confidence in releases.
Web Performance Metrics and Measurement
Understanding of how to measure, interpret, and act upon web performance data. Topics include Core Web Vitals such as First Contentful Paint, Largest Contentful Paint, and Cumulative Layout Shift, Time to First Byte, synthetic and real user monitoring, using tools such as Lighthouse, Chrome DevTools, and WebPageTest, establishing performance budgets, instrumentation and logging for real user metrics, benchmarking changes, and prioritizing optimizations based on user impact. Candidates should be able to design measurement strategies, run before and after comparisons, and integrate performance checks into development workflows.
Engineering Quality and Standards
Covers the practices, processes, leadership actions, and cultural changes used to ensure high technical quality, reliable delivery, and continuous improvement across engineering organizations. Topics include establishing and evolving technical standards and best practices, code quality and maintainability, testing strategies from unit to end to end, static analysis and linters, code review policies and culture, continuous integration and continuous delivery pipelines, deployment and release hygiene, monitoring and observability, operational run books and reliability practices, incident management and postmortem learning, architectural and design guidelines for maintainability, documentation, and security and compliance practices. Also includes governance and adoption: how to define standards, roll them out across distributed teams, measure effectiveness with quality metrics, quality gates, objectives and key results, and key performance indicators, balance feature velocity with technical debt, and enforce accountability through metrics, audits, corrective actions, and decision frameworks. Candidates should be prepared to describe concrete processes, tooling, automation, trade offs they considered, examples where they raised standards or reduced defects, how they measured impact, and how they sustained improvements while aligning quality with business goals.
Systematic Troubleshooting and Debugging
Covers structured methods for diagnosing and resolving software defects and technical problems at the code and system level. Candidates should demonstrate methodical debugging practices such as reading and reasoning about code, tracing execution paths, reproducing issues, collecting and interpreting logs metrics and error messages, forming and testing hypotheses, and iterating toward root cause. Topic includes use of diagnostic tools and commands, isolation strategies, instrumentation and logging best practices, regression testing and validation, trade offs between quick fixes and long term robust solutions, rollback and safe testing approaches, and clear documentation of investigative steps and outcomes.
Edge Case Handling and Debugging
Covers the systematic identification, analysis, and mitigation of edge cases and failures across code and user flows. Topics include methodically enumerating boundary conditions and unusual inputs such as empty inputs, single elements, large inputs, duplicates, negative numbers, integer overflow, circular structures, and null values; writing defensive code with input validation, null checks, and guard clauses; designing and handling error states including network timeouts, permission denials, and form validation failures; creating clear actionable error messages and informative empty states for users; methodical debugging techniques to trace logic errors, reproduce failing cases, and fix root causes; and testing strategies to validate robustness before submission. Also includes communicating edge case reasoning to interviewers and demonstrating a structured troubleshooting process.
Testability and Testing Practices
Emphasizes designing code for testability and applying disciplined testing practices to ensure correctness and reduce regressions. Topics include writing modular code with clear seams for injection and mocking, unit tests and integration tests, test driven development, use of test doubles and mocking frameworks, distinguishing meaningful test coverage from superficial metrics, test independence and isolation, organizing and naming tests, test data management, reducing flakiness and enabling reliable parallel execution, scaling test frameworks and reporting, and integrating tests into continuous integration pipelines. Interviewers will probe how candidates make code testable, design meaningful test cases for edge conditions, and automate testing in the delivery flow.
Testing Strategy and Error Handling
Combines broader testing strategy for systems with a focus on error handling, resilience, and user experience when failures occur. Topics include designing a testing strategy that covers unit tests, integration tests, end to end tests and exploratory testing, applying the testing pyramid, defining error boundaries and recovery paths, graceful degradation and fallback strategies, user feedback and error messaging, fault injection and resilience testing, logging and observability to detect and reproduce errors, and validating error handling behavior across environments and edge cases.
Testing and Debugging Frontend Code
Unit testing, integration testing, and end-to-end testing strategies for frontend. Using debugging tools effectively (browser dev tools, React DevTools). Understanding test coverage and maintainability of tests. Discussing debugging complex frontend issues.