SE Notes
Proven software engineering practices for quality and productivity.
Best practices are proven approaches that consistently produce superior results across diverse projects and organizations. They represent the collective wisdom of decades of software engineering experience—patterns that successful teams follow and that struggling teams often neglect. While no practice is universally optimal for every situation, these guidelines form a strong foundation for any software project.
Requirements Practices
Involve stakeholders early and continuously. Requirements gathered without stakeholder participation are requirements that will be wrong. Schedule regular reviews, demos, and feedback sessions throughout development—not just at the beginning and end.
Write testable requirements. Every requirement should have a clear, measurable acceptance criterion. "The system should be fast" is untestable and therefore useless. "Search results shall be returned within 2 seconds for queries against up to 1 million records" is testable and actionable.
Manage scope actively. Use techniques like MoSCoW prioritization (Must have, Should have, Could have, Won't have) to prevent scope creep. Formally evaluate every change request against schedule and budget impact before accepting it.
Maintain a requirements traceability matrix. Every requirement should trace forward to design elements, code modules, and test cases. This ensures nothing is forgotten during implementation and provides confidence that testing is complete.
Design Practices
Design for change. Identify the aspects most likely to change and isolate them behind stable interfaces. Database technology might change. UI frameworks evolve. Third-party APIs update. Design so that likely changes require modifying few modules.
Follow SOLID principles. Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, and Dependency Inversion produce code that is easier to understand, modify, and test.
Keep it simple (YAGNI—You Aren't Gonna Need It). Do not build infrastructure for requirements that do not yet exist. Premature abstraction creates complexity without delivering value. Build what you need today; refactor when tomorrow's needs actually materialize.
Document architectural decisions. Use Architecture Decision Records (ADRs) to capture why decisions were made—not just what was decided. Future maintainers (including your future self) need this context.
Implementation Practices
Write clean, readable code. Code is read far more often than it is written. Meaningful names, short functions, clear structure, and helpful comments (explaining why, not what) make code maintainable by the entire team.
Practice continuous integration. Merge code to the main branch multiple times daily. Each merge triggers automated builds and tests. This catches integration problems within minutes rather than days.
Review all code. No code reaches production without peer review. Reviews catch defects, share knowledge, maintain consistency, and improve team capability. Even senior developers benefit from having their code reviewed.
Automate testing. Manual testing does not scale and is not repeatable. Invest in automated unit tests, integration tests, and end-to-end tests that run on every commit. Aim for 80%+ code coverage with meaningful (not trivial) tests.
Refactor continuously. Technical debt accumulates naturally. Address it incrementally as part of regular development rather than allowing it to accumulate to crisis levels. Leave code cleaner than you found it.
Testing Practices
Test early, test often. Begin writing tests during (or before) implementation. Run the full test suite before every commit. Automated tests in CI/CD pipelines provide continuous quality feedback.
Test at multiple levels. Unit tests verify individual components. Integration tests verify interactions. System tests verify end-to-end behavior. Each level catches different types of defects.
Include negative testing. Do not only test the happy path. Test with invalid inputs, exceeded limits, missing data, concurrent access, and error conditions. Systems fail most often at their boundaries and in their error handling.
Separate test environments from production. Never test with production data without anonymization. Never deploy untested code to production. Maintain consistent test environments that mirror production configuration.
Project Management Practices
Estimate realistically. Add contingency (typically 20-50%) to account for the unknown. Track estimate accuracy over time to improve calibration. Use historical data from similar projects rather than optimistic guesses.
Communicate proactively. Share progress, blockers, and risks early and often. Bad news does not improve with age. Stakeholders who are surprised by problems lose trust; stakeholders who are informed early can help solve problems.
Conduct retrospectives. After each iteration or milestone, reflect on what went well and what should improve. Identify specific, actionable improvements and implement them immediately—retrospectives without follow-through are pointless.
Manage risk explicitly. Identify risks early, assess their probability and impact, develop mitigation strategies, and monitor risk indicators throughout the project. Address the highest risks first.
Operational Practices
Automate deployments. Manual deployment is error-prone and unrepeatable. Automated deployment pipelines ensure consistency, enable rapid rollback, and reduce deployment anxiety.
Monitor in production. You cannot fix problems you do not know about. Implement comprehensive monitoring (system health, business metrics, error rates) with alerting for anomalous conditions.
Plan for failure. Systems will fail. Design graceful degradation. Test disaster recovery procedures. Maintain runbooks for common incidents. Practice incident response before you need it.
Document operational procedures. How to deploy, how to roll back, how to scale, how to recover from common failures—document these procedures so any team member can respond to operational events.
Cultural Practices
Foster psychological safety. Teams where people fear blame hide problems, avoid risk, and resist admitting mistakes. Teams where it is safe to fail, ask questions, and challenge assumptions innovate faster and catch problems earlier.
Invest in learning. Technology evolves continuously. Teams that stop learning fall behind. Allocate time for training, experimentation, conference attendance, and knowledge sharing.
Celebrate quality. Recognize and reward practices that prevent defects, not just practices that deliver features quickly. A team that ships quality code sustainably outperforms a team that ships quickly but spends months fixing production issues.
Exam Focus
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Interview Use
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