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').
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.
Software Testing and Assertions
Core software testing and debugging practices, including designing tests that exercise normal, edge, boundary, and invalid inputs, writing clear and maintainable unit tests and integration tests, and applying debugging techniques to trace and fix defects. Candidates should demonstrate how to reason about correctness, create reproducible minimal failing examples, and verify solutions before marking them complete. This topic also covers writing effective assertions and verification statements within tests: choosing appropriate assertion methods, composing multiple assertions safely, producing descriptive assertion messages that aid debugging, and structuring tests for clarity and failure isolation. Familiarity with test design principles such as test case selection, test granularity, test data management, and test automation best practices is expected.
Advanced Debugging and Root Cause Analysis
Systematic approaches to complex debugging scenarios: intermittent failures, race conditions, environment-dependent issues, infrastructure problems. Using logs, metrics, and instrumentation effectively. Differentiating between automation issues, environment issues, and application defects. Experience with advanced debugging tools and techniques.
Code Review Philosophy and Practice
Covers the approach to conducting effective code reviews, including what reviewers look for and how reviewers provide constructive feedback. Topics include evaluating correctness, design and architecture, complexity, test coverage and quality, performance, security considerations, readability and maintainability, and consistency with style and team conventions. Includes techniques for balancing thoroughness and development velocity, using checklists and automation to reduce repetitive comments, unblocking reviewees, preserving morale and psychological safety, resolving disagreements, and using code reviews as opportunities for mentoring and knowledge transfer. Candidates may also discuss tooling, review workflow, time boxing, and metrics for measuring review effectiveness such as review turnaround time and post review defect rates.
Attention to Detail and Quality
Covers the candidate's ability to perform careful, accurate, and consistent work while ensuring high quality outcomes and reliable completion of tasks. Includes detecting and correcting typographical errors, inconsistent terminology, mismatched cross references, and conflicting provisions; maintaining precise records and timestamps; preserving chain of custody in forensics; and preventing small errors that can cause large downstream consequences. Encompasses personal systems and team practices for quality control such as checklists, peer review, audits, standardized documentation, and automated or manual validation steps. Also covers follow through and reliability: tracking multiple deadlines and deliverables, ensuring commitments are completed thoroughly, escalating unresolved issues, and verifying that fixes and process changes are implemented. Interviewers assess concrete examples where attention to detail prevented problems, methods used to maintain accuracy under pressure, how the candidate balances speed with precision, and how they build processes that sustain consistent quality over time.
Edge Case Identification and Testing
Focuses on systematically finding, reasoning about, and testing edge and corner cases to ensure the correctness and robustness of algorithms and code. Candidates should demonstrate how they clarify ambiguous requirements, enumerate problematic inputs such as empty or null values, single element and duplicate scenarios, negative and out of range values, off by one and boundary conditions, integer overflow and underflow, and very large inputs and scaling limits. Emphasize test driven thinking by mentally testing examples while coding, writing two to three concrete test cases before or after implementation, and creating unit and integration tests that exercise boundary conditions. Cover advanced test approaches when relevant such as property based testing and fuzz testing, techniques for reproducing and debugging edge case failures, and how optimizations or algorithmic changes preserve correctness. Interviewers look for a structured method to enumerate cases, prioritize based on likelihood and severity, and clearly communicate assumptions and test coverage.
Quality and Testing Strategy
Designing and implementing a holistic testing and quality assurance strategy that aligns with product goals, customer experience, and business risk. Candidates should be able to articulate a quality philosophy and trade offs between speed to market and product stability, define release criteria, and explain where and when different types of testing belong in the development lifecycle. Core areas include unit tests, integration tests, end to end tests, manual exploratory testing, building a test coverage plan and the test pyramid, and risk based testing and quality risk assessment to prioritize business critical flows. This also covers test automation strategy and selection of tests to automate, reducing flakiness and maintenance cost, test infrastructure and environment management, test data strategies, device and operating system compatibility testing, and observability and production monitoring including crash reporting and analytics to inform priorities. Candidates should be prepared to discuss shift left and continuous testing practices, how testing integrates with continuous integration and continuous deployment pipelines, gating and deployment considerations, defect prevention techniques such as code quality and static analysis, cross functional ownership of quality, and metrics and reporting to measure quality and guide improvements, such as test coverage, pass rates, mean time to detection, mean time to resolution, defect escape rate, and cost of quality. Interviewers may ask candidates to design a testing strategy for a feature or product area, prioritize tests and investments, justify trade offs given time and resource constraints, and describe how they would instrument monitoring and feedback loops for production issues.