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Quell Documentation

Untested edge cases will bite you in production. Quell finds them before they do.

Quell reads your Python codebase — docstrings, Pydantic models, type annotations, guard clauses — extracts every testable requirement, checks which ones have no test, and tells you exactly where your coverage is blind.

For edge cases it can prove automatically, Quell writes ready-to-run pytest tests. For the ones it can't, it flags them with exact reasons so you know where to look.

What Quell does

  1. Finds — scans your code for untested edge cases across every spec source
  2. Writes — generates verified pytest tests for confident cases and writes them to disk
  3. Flags — documents every gap it can't auto-test, with exact reasons

The three-bucket output

Every edge case Quell finds lands in one of three buckets:

  • ✓ WRITTEN — Test generated, verified through the 5-gate pipeline, written to your test file
  • ~ SCAFFOLDED — Stub written with a clear TODO, ready for you to complete
  • ✗ FLAGGED — Documented gap with exact reason (side effect, non-determinism, external service)

Quick start

pip install quelltest
quell find src/

See the Quickstart guide for a full walkthrough.

Why Quell?

Line coverage tells you which lines ran. It doesn't tell you whether your tests actually catch bugs.

Quell uses a 5-gate verification pipeline: any test it writes must both pass on correct code and fail when the requirement is violated. If a test can't prove this, it becomes a scaffold or a flag — never silently dropped.

This is what we call the moat. It's what makes Quell's tests trustworthy after install.

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Quickstart