Changelog • mutator

mutator 0.2.2

The reusable GitHub Actions workflow now installs mutator from CRAN by default, instead of from the tip of the GitHub repository. A new mutator-source input selects cran (default), r-universe, github, or local (mutator is the package under test). When CRAN or r-universe cannot provide the package, the workflow falls back to PRL-PRG/mutator at the tag given by the new mutator-ref input, which defaults to the release the workflow is versioned with; set mutator-fallback: false to fail instead. The existing mutator-spec input still accepts a raw pak spec and now overrides mutator-source; it no longer defaults to GitHub.

CRAN release: 2026-08-02

This release addresses feedback received from CRAN during the review of the initial submission:

Removed the default output directory from mutate_file(), so callers must explicitly choose where mutant files are written.
Restored the caller’s working directory immediately with on.exit() in all package test-runner and coverage code paths that temporarily change it.

It also improves Windows support:

Mutant package copies now link directories with junctions (Sys.junction()) rather than symbolic links on Windows, which unlink() cannot remove; this avoids leftover reparse points and the accompanying R CMD check warnings.

Added first-class tinytest support. A package with an inst/tinytest directory is now auto-detected and its mutants are run in-process with pkgload::load_all() and tinytest::run_test_dir(), without an install per mutant, including coverage-guided test selection.
Added a strategy argument to mutate_package() to override test-framework auto-detection. Accepted values are "auto" (the default), "testthat", "tinytest", "tinytest-installed", and "installed".
Added a tinytest-installed strategy that installs each mutant and runs tinytest::test_package(). It is a fallback for packages whose in-process load diverges from an installed copy and unlike the generic installed-tests fallback it still supports coverage-guided selection.
Reworked the README and configuration vignette, documenting how the test strategy is selected and when to override it.
Fixed the per_file coverage backend to forward the package’s tests/testthat.R harness arguments (notably any filter) to testthat::test_dir(), matching the record_tests backend.

Fixed coverage-guided baseline runs for packages with native code by compiling native sources before mutant execution.
Fixed the record_tests coverage backend so it forwards the selected CRAN mode consistently.
Updated the reusable GitHub Actions workflow to install imputesrcref from its default branch, replacing the removed development-branch reference.
Expanded mutation-system coverage across execution modes and raised mutator’s own test coverage above 90% without adding slow integration tests.