Software Engineering Cheat Sheet

Software Development Life Cycle (SDLC) Models

Model	Description	Advantages	Disadvantages	Best Use Case
Waterfall	Sequential development phases	Simple, structured, well-documented	Inflexible, late testing, difficult to change	Well-defined requirements, stable technology
Agile	Iterative, customer-focused development	Flexible, customer collaboration, rapid delivery	Requires customer involvement, difficult to estimate	Changing requirements, customer collaboration
Iterative	Develop in iterations with feedback	Early error detection, risk management	Resource-intensive, complex management	Large projects, evolving requirements
Spiral	Risk-driven, prototype-based	Risk management, flexible	Complex, expensive, requires expertise	High-risk projects, large systems
V-Model	Testing phase for each development phase	Systematic, early testing planning	Inflexible, late discovery of issues	Regulated industries, safety-critical
DevOps	Development and operations integration	Continuous delivery, automation, collaboration	Requires cultural change, learning curve	Continuous deployment, automation

Agile Methodologies

Methodology	Key Principles	Key Practices	Best For
Scrum	Iterative sprints, self-organizing teams	Sprint planning, daily standups, retrospectives	Complex projects, cross-functional teams
Kanban	Visual workflow, continuous delivery	Visual boards, WIP limits, flow optimization	Continuous flow, maintenance projects
Extreme Programming (XP)	Customer satisfaction, rapid feedback	Pair programming, TDD, continuous integration	Changing requirements, high-quality code
Lean	Eliminate waste, optimize workflow	Value stream mapping, continuous improvement	Efficiency, waste reduction
Crystal	People and interaction over processes	Reflective improvement, personal communication	Small teams, high-criticality projects

Software Testing Types

Type	Focus	When	Techniques	Tools
Unit Testing	Individual components	During development	White box, equivalence partitioning	JUnit, NUnit, PyTest
Integration Testing	Module interactions	After unit testing	Top-down, bottom-up, sandwich	TestNG, Mockito, JMock
System Testing	Complete system	After integration	Black box, functional testing	Selenium, JMeter, LoadRunner
Acceptance Testing	Business requirements	Before delivery	User acceptance, alpha/beta testing	Cucumber, FitNesse, UFT
Regression Testing	Ensure no new bugs	After changes	Retest, selective retest	Selenium, TestComplete, Ranorex
Performance Testing	Speed, stability, scalability	Before production	Load, stress, endurance testing	JMeter, LoadRunner, Gatling
Security Testing	Vulnerabilities	Throughout development	Penetration testing, vulnerability scanning	OWASP ZAP, Burp Suite, Nessus

Design Patterns

Pattern	Category	Purpose	Implementation	Benefits
Singleton	Creational	Ensure single instance	Private constructor, static instance	Controlled access, reduced memory
Factory	Creational	Create objects without specifying class	Factory method, abstract factory	Loose coupling, flexibility
Observer	Behavioral	Define one-to-many dependency	Subject, observer interfaces	Loose coupling, broadcast
Strategy	Behavioral	Define family of algorithms	Interface for algorithms	Runtime algorithm selection
Decorator	Structural	Add responsibilities dynamically	Wraps original object	Flexible alternative to subclassing
Adapter	Structural	Convert interface to compatible one	Wrapper pattern	Make incompatible interfaces work together
Command	Behavioral	Encapsulate request as object	Command interface, invoker	Parameterize, queue, log requests
Facade	Structural	Provide unified interface	Simple interface to complex system	Simplify complex subsystems

Software Quality Metrics

Category	Metric	Description	Measurement	Target
Productivity	Lines of Code (LOC)	Size of software	Count of source lines	Context-dependent
Productivity	Function Points	Functionality provided	Count of inputs, outputs, files	10-15 FP per person-month
Productivity	Code Reuse	Reusable components	Percentage of reused code	60-80%
Quality	Defect Density	Defects per size unit	Defects / KLOC or FP	1-5 defects/KLOC
Quality	Code Coverage	Code tested	Percentage of code exercised	80-90%
Quality	Cyclomatic Complexity	Code complexity	Number of linearly independent paths	3-7 per method
Maintenance	Maintainability Index	Effort to maintain	Based on complexity, lines, comments	65-100 (higher better)
Maintenance	Mean Time to Repair (MTTR)	Time to fix defects	Average time to resolve issues	As low as possible

Software Configuration Management

Activity	Purpose	Tools	Best Practices
Version Control	Track changes to code	Git, SVN, Mercurial	Commit frequently, use branches, meaningful commit messages
Build Management	Automate build process	Maven, Gradle, Ant, Make	Automate, consistent environment, dependency management
Release Management	Manage software releases	Jenkins, Bamboo, TeamCity	Automated testing, staging environments, rollback plans
Change Management	Control changes to software	Issue trackers, change logs	Impact analysis, approval process, documentation
Configuration Management	Manage system configurations	Ansible, Puppet, Chef	Infrastructure as code, version control, automation

Requirements Engineering

Activity	Description	Techniques	Deliverables
Requirements Elicitation	Gather requirements from stakeholders	Interviews, surveys, observation, prototyping	Requirements document
Requirements Analysis	Understand and organize requirements	Use cases, user stories, context diagrams	Analysis model
Requirements Specification	Document requirements formally	SRS document, specifications	Software Requirements Specification
Requirements Validation	Verify requirements are correct	Reviews, prototyping, model checking	Validated requirements
Requirements Management	Track and control requirements	Traceability matrices, tools	Requirements traceability

Software Architecture Patterns

Pattern	Description	Advantages	Disadvantages	Use Case
Layered (n-tier)	Organized into horizontal layers	Separation of concerns, maintainable	Performance overhead, rigid structure	Enterprise applications
Client-Server	Client requests, server responds	Separation of concerns, scalability	Single point of failure, network dependency	Web applications
Microservices	Small, independent services	Scalability, technology diversity	Complexity, network latency	Large, complex applications
Event-driven	Components react to events	Loose coupling, scalability	Complexity, debugging difficulty	Real-time applications
Model-View-Controller	Separate data, presentation, logic	Separation of concerns, maintainable	Complexity, over-engineering	GUI applications
Repository	Mediates between domain and data mapping	Decoupling, testability	Complexity, performance	Data-centric applications

Software Maintenance Types

Type	Purpose	Examples	Percentage of Effort
Corrective	Fix defects	Bug fixes, error corrections	20%
Adaptive	Modify for environment changes	New OS, hardware changes, regulatory changes	25%
Perfective	Improve performance/functionality	Performance improvements, feature enhancements	50%
Preventive	Prevent future problems	Code refactoring, documentation updates	5%

Project Management in Software Engineering

Aspect	Description	Techniques/Tools	Key Considerations
Project Planning	Define scope, schedule, resources	WBS, Gantt charts, PERT, critical path	Accurate estimation, risk assessment
Project Estimation	Estimate effort, time, cost	COCOMO, Function points, expert judgment	Historical data, team experience
Risk Management	Identify, analyze, mitigate risks	Risk matrix, mitigation plans	Early identification, contingency plans
Quality Management	Ensure software quality	Quality standards, reviews, testing	Quality planning, continuous improvement
Team Management	Manage human resources	Team building, communication, motivation	Skills, roles, communication
Change Management	Control requirement changes	Change control process, impact analysis	Documentation, approval process