butcher 0.3.0

Mutation testing for Dart; rewrites the source into mutants and scores which ones the tests kill.

Changelog

0.3.0

• --test <path>, or tests in butcher.yaml, runs the named test files instead of every *_test.dart, so a bundled suite pays its startup once.
• --sandbox-scope=package also skips directories holding their own pubspec.yaml that no kept package reaches, such as nested workspace roots.

0.2.1

• --sandbox-scope=package no longer breaks a root pubspec whose workspace: list is followed by another key.

0.2.0

• Flutter packages: a package depending on the Flutter SDK runs its suites with flutter test and resolves with flutter pub get, using the flutter beside the running dart or under FLUTTER_ROOT. Covered mutants run the whole suite for now; --max-heap-mb is not supported for them yet.
• --files mutates only the named lib/ files, and --diff-base <ref> only the lib/ files changed since a git ref, uncommitted and untracked ones included. A scoped run records its scope under the report's config.scope.
• butcher.log records each mutant as started before its suite runs, and an interrupted or aborted run prints the mutants still in flight, so a crashed run shows which mutants it was running.
• --max-heap-mb caps the heap of every test process butcher starts. A mutant that exhausts it is reported as memoryError instead of taking the host down, and scores as neither killed nor survived.
• A coverage/lcov.info older than any file in lib/ or test/ is skipped as stale and coverage is collected instead, so new lines are no longer reported as noCoverage. The console names the coverage source of every run.
• --sandbox-scope=package copies only the pub workspace members the selected package reaches into each sandbox, instead of the whole workspace. The default, workspace, is unchanged.

0.1.0

• First release. butcher is a fork of the MIT-licensed radioactive_dart package by Ricardo Boss, taken with its full history, renamed, and split into a pub workspace; the upstream copyright notice travels with it.
• The butcher CLI mutates lib/, prints per-outcome counts, MSI and covered-code MSI, and writes a Stryker JSON report (--output).
• Mutants are generated from the analyzer's AST: arithmetic, relational, equality and logical operators, boolean literals, and nullability mutators for ??, ?. and injected null. Identity replacements are rejected and promotion-breaking flips are skipped rather than reported.
• Outcomes are killed, survived, noCoverage, timeout, unviable and runError. Timeouts are inconclusive: they enter neither score, and a timeout rate is printed whenever any occur. A run with no scoreable mutants reports no MSI and fails --threshold.
• Mutants that fail static analysis report as unviable without a test run, so a compiler failure is never counted as a kill.
• Coverage routes each mutant to the test files that cover its line, cheapest first, in one --fail-fast run. A project's own coverage/lcov.info is picked up automatically, --coverage supplies one, and otherwise coverage is collected in one extra suite run; --no-collect-coverage treats all code as covered.
• Each worker tests in its own sandbox, a temp-directory copy of the project holding what the repository's git listing names, so the project's own gitignore rules decide it. Selecting a pub workspace member copies the whole workspace while keeping tests, generation, coverage and report output rooted at that member.
• exclude in a butcher.yaml at the project root lists globs of files never mutated; generated sources such as .g.dart and .freezed.dart are skipped without it.
• A red baseline aborts the run before generation; the green baseline's duration sets each mutant's deadline, so a slow selection is not a timeout.
• --jobs classifies in parallel, one sandbox per worker. A timed-out suite is killed with everything it spawned, and interrupting a run reaps every suite still in flight.
• --threshold gates on the MSI and --max-timeouts on timed-out mutants. Exit codes are 0 success, 1 gate failed, 64 usage, 70 aborted run.
• Wide-event CLEF logging: one tool log plus one log per sandbox, each mutant's suite output kept as a capped excerpt; --verbose renders the events on a terminal. All temp data lives under one root, redirectable with BUTCHER_TEMP, cleaned at the next run's startup under an exclusive lock.
• Published to pub.dev on 2026-09-23.