Tools and practices to help you deal with legacy code
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This document outlines strategies for improving legacy code, emphasizing steps such as understanding the production environment, removing unused code, enhancing deployability, and improving code quality and design. It details practices like using code analysis tools, implementing versioning strategies, and adopting modern coding standards. Additionally, it suggests architectural approaches like onion and hexagonal architecture to refine software structure and maintainability.
Tools and practices to help you deal with legacy code
- 1. tools, practices and principles My recipe for dealing with legacy code Dennis Doomen @ddoomen | The Continuous Improver | Aviva Solutions
- 2. About Me Hands-on architect in the .NET space with 27 years of experience on an everlasting quest for knowledge to build the right software the right way at the right time @ddoomen | The Continuous Improver | Aviva Solutions
- 4. Win a 1-year license for Jetbrains Rider twitter: ddoomen mastodon: @ddoomen.mastodon.social bluesky: @ddoomen.bsky.social
- 5. How I work @ddoomen | The Continuous Improver | Aviva Solutions
- 6. My typical improvement flow Understand the production environment Understand the code base Find dead and unused code Build a safety net Improve deployability Improve code quality Improve code design Improve architecture
- 7. Understand the production environment @ddoomen | The Continuous Improver | Aviva Solutions
- 8. Get .EXE, .DLLs, logs and config files from production environment
- 9. Compare .NET binaries with source control
- 10. Analyze log files and crash reports
- 11. Get it to run locally
- 12. Understanding the code @ddoomen | The Continuous Improver | Aviva Solutions
- 13. Inspect the project dependencies, folder names and namespaces
- 14. Use Type Dependencies Diagram in R#
- 15. Use NDepend
- 17. Draw your own class diagrams
- 18. Use your IDE
- 19. Let AI tooling explain the code
- 20. Track all notes in a single place
- 21. Find and remove dead code @ddoomen | The Continuous Improver | Aviva Solutions
- 22. Reduce code visibility Remove unused code Remove commented-out code
- 23. Build a safety net @ddoomen | The Continuous Improver | Aviva Solutions
- 25. Characteristics Test Suite Add characteristics tests Application Legacy Code Base Production Backup
- 26. Use Test Containers Characteristics Test Suite Application Legacy Code Base Linux Test Container SQL Server
- 27. Add a couple of UI tests Browser Tests Application Legacy Code Base Production Backup Legacy Web UI
- 28. Improve deployability @ddoomen | The Continuous Improver | Aviva Solutions
- 29. Add build “script” that can run locally
- 30. Adopt versioning strategy and branch naming conventions https://quangnguyennd.medium.com/git-flow-vs-github-flow-620c922b2cbd
- 32. Adopt logging and exception strategy
- 33. Automate deployments (e.g. Pulumi, Ansible, etc)
- 34. Improve code @ddoomen | The Continuous Improver | Aviva Solutions
- 35. Treat all warnings as errors and fix them
- 36. Add .editorconfig to allow auto-formatting (for VS, VS Code and Rider)
- 37. Add Roslyn Analyzers • XML comment formatting • LINQ performance improvements • Nested conditional statements • Long methods • Single type per file • Correct exception types • Proper async supports
- 38. Enable C# Nullable Types
- 39. Move to .NET 6+ and bump C# version • file-scoped namespaces • global usings • target-type new • switch expression • string interpolation • raw strings • pattern matching • or operator
- 40. Using PolySharp to enable newer C# features on older frameworks
- 42. Improve naming whenever you can
- 43. Encapsulate access to properties through methods
- 44. Improve design @ddoomen | The Continuous Improver | Aviva Solutions
- 45. Organize by functionalities / capabilities
- 46. Apply DRY within those “boundaries” Duplicated Service 1 Duplicated Service 1 Duplicated Service 2 Duplicated Service 2 Duplicated Service 1 Centralized Service 3 Extension Methods Extension Methods Extension Methods Extension Methods Helpers Helpers Helpers Helpers
- 47. Service Service Service Service Service Centralized Service Align your test scope with those “boundaries”
- 48. Avoid technical folders and organize code by functionalities / capabilities Functional Folders “Unit” of (integration) testing DRY within boundaries Can be used to clarify “public” parts Only unit tested for specific reasons Role-based interface name
- 49. Treat adjacent folders as separate boundaries
- 51. Adopt an architecture style that embraces the DIP Order Processing IStoreOrders<T> + Query<T>(); + Add<T>(); + Delete<T>(); NHibernate Repository Order Processing IStoreOrders + GetIncompleteOrders(minValue); + StoreOrder(); + CompleteOrder(); OrderRepository VS
- 52. Main Package Application Bunch of blocks that can be used directly Uses composition over inheritance Convenience blocks that don’t hide the magic Shared Package Contract Contract Only depend on more abstract packages… Stable Package …or depend on more stable packages Auxiliary Package Blocks that are not used together do not belong together Optional Dependency Dependency Package Consumers should not be faced with optional dependencies No cyclic dependencies Apply principles of successful package management
- 53. Improve architecture @ddoomen | The Continuous Improver | Aviva Solutions
- 54. Use your learnings to visualize the target architecture
- 56. -or- Hexagonal Architecture (a.k.a. Ports & Adapters) Domain Application Primary Port Primary Port Secondary Port Secondary Port Web Adapter API Adapter Database Adapter Adapter Dependencies Dependencies
- 58. Q&A Join me at 14:30 in room 7 Meet me near room 11 Also find me at twitter: ddoomen mastodon: @ddoomen.mastodon.social bluesky: @ddoomen.bsky.social email: dennis.doomen@avivasolutions.nl slack: fluentassertions.slack.com