Craftsmanship Low-Level II

The direct continuation of Atlas I's Craftsmanship Low-Level — always active across every branch, the same way the original was. Where Atlas I applied TDD, fuzzing, and contracts to memory-unsafe C in general, this branch applies the same discipline to stateful, concurrent systems: protocol parsers, the database engine, and code where the bug only shows up under load or after a crash.

Planned notes

• Testing a protocol parser: feeding the HTTP parser malformed input as a first-class test case
• Testing Git's object format parser: corrupted objects, truncated files, wrong hashes
• Race conditions in practice: writing a test that reliably reproduces one
• ThreadSanitizer (TSan) in the build: what it catches that review doesn't
• Fuzzing binary formats: the B-Tree page format and the WAL format with libFuzzer/AFL++
• Fuzzing the HTTP parser against the spec's edge cases
• Property-based testing for the database engine: invariants that must hold after any sequence of operations
• TDD when state lives on disk, not memory: structuring tests around a throwaway data directory
• Crash-recovery testing: killing the process mid-write and asserting on recovery
• Contracts and asserts for the B-Tree's structural invariants
• Code review checklist for memory-unsafe, concurrent C

Core sources

• Test-Driven Development for Embedded C (Grenning) — TDD discipline for systems code, already the spine of Atlas I's craftsmanship branch.
• libFuzzer and AFL++ documentation — fuzzing binary formats and parsers, reused from Atlas I.
• "Property-Based Testing with PropEr, Erlang, and Elixir" — referenced only for the technique of property-based testing, not the language.
• ThreadSanitizer documentation — practical TSan usage on real concurrent C code.

Connects to: HTTP Server from Scratch · Mini Git · KV Store & Durability