Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[0.3.0] - 2026-08-19

UnusedSetupKeysInTests and UnusedSetupKeysPerTest now resolve a context handed to a def/defp in the same file, following it through helper chains, pipes and %{ctx | ...} copies, and counting the keys that helper reads. A test that hands its context to something unresolvable — imported or remote — is treated as opaque and consumes every key in scope, so the checks stay quiet rather than report a live fixture as dead. Previously any test that passed ctx to a helper read as using nothing.
UnusedSetupKeysPerTest now flags only a test that consumes none of the setup keys in scope for it. The previous rule — every test must consume every in-scope key — treated a shared fixture as a defect and was too noisy to enable: 1747 reports against 152 under the new rule, on the same 767-file suite. Its message and moduledoc now explain the cost being avoided (ExUnit has no lazy let), and document the case it cannot see: a setup whose inserted rows are queried without being named.

usage-rules.md, consumed by usage_rules, documenting how to respond to each check — starting with the rule that a report is a suspicion to verify, not a licence to delete code.
SephiaCredo.TestContext, the shared AST reading behind both setup-key checks.

AshCodeInterfaceReadWithArgs — flags define :name, action: :read, args: [...] inside code_interface blocks. Ash's generic :read action declares no inputs, so the resulting function raises Ash.Error.Invalid.NoSuchInput at runtime.
AssertWithoutAssertion — flags assert pattern = expr in test files where the bound variables are never used afterwards. The match succeeds vacuously and tests nothing.
ProcessSleepInTests — flags Process.sleep/1 in *_test.exs files, including inside setup and setup_all blocks. Causes flakes and slows the suite.
RawRuntimeError — flags raise "msg" and raise RuntimeError, .... Both lower to RuntimeError, defeating error-tracker grouping (every message becomes its own issue).
SysGetStateWithoutTimeoutInPoll (opt-in) — flags :sys.get_state/1 inside a polling fn without a surrounding try/catch :exit. Configurable via poll_functions:. Not added by the installer; opt in manually.

StructComparisonOperator replaces NoDateTimeOperatorCompare. In addition to Date, Time, DateTime, and NaiveDateTime, it now covers Decimal and Version, and accepts an extra_modules config for any other struct that defines its own compare/2.
mix sephia_credo.install registers the new default-on checks alongside the existing ones.

NoDateTimeOperatorCompare — superseded by StructComparisonOperator. See the "Upgrading from 0.1" section of the README for the one-line migration.

Initial release with AppendInLoop, NoDateTimeOperatorCompare, UnusedSetupKeysInTests, UnusedSetupKeysPerTest.