evankford/pest-plugin-mutate-lines

Pest Plugin: Mutate Lines

Scope Pest mutation testing to the lines you actually changed, instead of every line of every covered class.

Long-lived classes can take minutes to mutate in full. While you iterate on one method, this plugin limits --mutate to your diff or to explicit line ranges.

Installation

composer require evankford/pest-plugin-mutate-lines --dev

Pest discovers the plugin automatically. Requires Pest 5 and pestphp/pest-plugin-mutate 5.

Usage

# Lines changed vs HEAD: uncommitted edits plus every line of untracked .php files
vendor/bin/pest --mutate --mutate-diff tests/Unit/FooTest.php

# Lines changed since the merge base with a ref (committed + uncommitted)
vendor/bin/pest --mutate --mutate-diff=origin/main tests/Unit/FooTest.php

# Explicit ranges, relative to the project root; repeat the flag for more files
vendor/bin/pest --mutate --mutate-lines=src/Foo.php:12,40-55 tests/Unit/FooTest.php

--mutate-diff and --mutate-lines can be combined; the selections are merged.

Notes

• Flags need =. --mutate-lines src/Foo.php:12 (with a space) falls through to PHPUnit and errors.
• Selected lines are intersected with what --mutate would normally mutate (your covers() / --class / --path scope), never widened.
• Nodes that span a selected line (e.g. the enclosing method's visibility) are mutated too. Pure deletions select nothing.
• The INFO Mutating only N selected lines across M files banner confirms the flag took effect. 0 Mutations means none of the selected lines belong to the classes being mutated.
• A scoped 100% says nothing about the untouched lines of a class. Iterate with these flags, then run one plain --mutate before calling the work done.

Compatibility

LineRangeMutationGenerator extends pest-plugin-mutate's internal MutationGenerator, so a minor release of that package could break this one. CI runs against both the lowest and the latest supported versions.

Development

composer test         # rector, pint, phpstan, unit tests
composer test:mutate  # mutation tests (needs pcov or xdebug), must stay at 100%

License

MIT. See LICENSE.md.