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').
Logging Tracing and Debugging
Covers design and implementation of observability and diagnostic tooling used to troubleshoot applications and distributed systems. Topics include structured machine readable logging, log enrichment with context and correlation identifiers, log aggregation and indexing, retention and cost trade offs, and searchable queryability. It also includes distributed tracing to follow request flows across services, trace sampling and propagation, and correlating traces with logs and metrics. For debugging, include production safe debugging techniques, live inspection tools, core dump and profiling strategies, and developer workflows for reproducing and isolating issues. Reporting aspects cover test and run reporting, generating dashboards and HTML reports, capturing screenshots or video on failure, and integrating diagnostic output into continuous integration and monitoring pipelines. Emphasize tool selection, integration patterns, alerting on diagnostic signal, privacy and security considerations for logs and traces, and practices that make telemetry actionable for incident response and postmortem analysis.
Error Handling and Fault Tolerance
Techniques for detecting, containing, and recovering from hardware and software faults in constrained systems. Topics include input validation, timeout and retry policies, watchdog timer usage, safe and deterministic fallback or degraded modes, structured error propagation and logging, diagnosability and telemetry for failures, idempotent operation design, graceful restart strategies, and testing edge cases through fault injection. Candidates should explain how they balance complexity, resource overhead, and reliability goals.
Field Support and Diagnostics
Design embedded systems for diagnosability and maintainability in the field through built in diagnostic modes, structured logging, telemetry, health checks, and remote monitoring. Topics include designing log formats and retention policies, circular logs and log rotation, crash dumping, health telemetry and alerting, over the air updates and safe rollback, and on device self tests and recovery modes. Candidates should discuss trade offs between diagnostic verbosity and constraints such as flash usage, power consumption, and telemetry bandwidth, as well as privacy and security concerns for field data. Explain how to make field faults actionable with useful metrics, how to reproduce intermittent failures, and strategies to reduce support costs through better observability and remote repro techniques.
Hardware Simulation and Mock Interfaces
Approaches to building and testing firmware without direct access to physical boards. Cover register and peripheral simulation, emulator and virtual platform usage, creating mock interfaces and test doubles for sensors and actuators, designing hardware abstraction layers to enable host based unit testing, hardware in the loop strategies, fault injection techniques, and continuous integration pipelines that exercise firmware tests. Discuss trade offs between fidelity of simulation and cycle time to maintainable, reliable test suites.
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.
Error Handling and Robustness
Designing firmware and system level mechanisms to detect, contain, and recover from faults and degraded conditions. Topics include watchdog timers and health monitoring, timeout and retry strategies, input validation and sanity checks, checksum and error detection for communication, graceful degradation and safe states, redundancy and fallback modes for critical components, brown out and power failure handling, and strategies for logging and telemetry within constrained storage and bandwidth. Also covers fault injection testing, automated recovery flows, clear diagnostic modes, and trade offs between availability, complexity, and predictable behavior.
Embedded Systems Issues and Prevention
Covers common reliability, stability, and correctness problems unique to embedded and resource constrained systems and how to prevent or detect them. Topics include memory problems such as stack overflow, heap fragmentation, and memory leaks; concurrency and timing issues such as race conditions, priority inversion, interrupt storms, and real time scheduling pitfalls; hardware related failures such as watchdog resets, brownout and power sequencing problems, electromagnetic interference and signal integrity concerns; and environment driven failures such as thermal and supply issues. Candidates should understand defensive programming and design practices for embedded targets including static allocation strategies, bounds checking, use of safe coding guidelines, static analysis and MISRA style rules, careful interrupt and driver design, priority inheritance or other inversion mitigation, watchdog configuration, debouncing and rate limiting, and EMI and power filtering techniques. Include diagnostic and validation approaches such as hardware bring up methods, use of JTAG and trace, logic analyzers and oscilloscopes, on device logging and telemetry, fault injection and stress testing, postmortem analysis and built in self test. Emphasize trade offs between performance, determinism, safety, and resource constraints and how design decisions affect failure modes and prevention strategies.
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.
Testing Debugging and Instrumentation
Testing strategies and observability practices for software and hardware systems, including embedded contexts. Topics include unit testing, integration testing, hardware in the loop testing, test harnesses, test automation, and trade offs when testing resource constrained systems. Instrumentation covers logging design, metrics, tracing, telemetry, and debug interfaces that make systems observable in development and production. Debugging techniques include use of debuggers, serial logging, signal capture, oscilloscope traces, remote debugging, and structured troubleshooting workflows. Discuss design decisions that balance visibility against performance and safety requirements, how to make systems testable and instrumented from the start, and how to interpret instrumentation to localize faults and validate fixes.