swift-io-seam-testing

Refactors Swift code that reads or writes files, resolves directories, or contacts UserDefaults, the Keychain, or the network so each external concern sits behind one narrow Sendable protocol, with production conformers wired through default initializer arguments, saves that create missing parent folders, a busy guard that rejects overlapping read-modify-write transactions, and an in-memory actor double that stages bytes, plants one-shot per-URL read or write faults, and logs write attempts. Swift Testing then covers the missing-environment branch, genuinely malformed bytes, injected retrieval faults, and failed saves without touching storage. Use when Swift code performs input or output and needs deterministic, side-effect-free unit tests, when a failure path cannot be reproduced on a real device, or when one module must behave identically in the app, the test target, and SwiftUI previews. Not for UI or snapshot testing, performance tuning, or types that never contact an external service.

Version

v1.0.0

Size

22 KB

Updated

2026-10-11

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