Extracting Specifications from Legacy Software with Elixir
summary
Extracts executable, human-readable specifications from real codebases: parses structure, generates C4-style diagrams, and emits text specs that are then turned into integration tests. Uses Elixir plus local agent tooling (mentions Tidewave) to map schemas, surface surprising dependencies (e.g., cloud code exfiltrating data), and found an untested BlueSky data plane with ~19 plugins and 96 endpoints. Demonstrates Surveyor producing specs and an Essay framework running them as runnable specs, and shows the approach working end-to-end on multiple legacy projects.
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chapters (9)
- 0:00Legacy software and specs
- 6:11Ownership of legacy systems
- 8:21Code into readable specs
- 10:58Making specs runnable with Essay
- 13:10Timet Teller case study
- 15:47Cloud Code rewrite case study
- 19:04Blue Sky data plane case study
- 26:17Tools state and next steps
- 27:21Q&A
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