mutate

name	mutate
description	Run mutation testing with cargo-mutants. Use after writing tests to verify they actually catch regressions — survivors indicate weak assertions.

Run mutation testing on git-prism using cargo-mutants.

Default: Targeted Run

If the user specifies files or modules, scope the run:

cargo mutants -- -f <file_or_pattern>

If no scope specified, run on the most recently changed files:

# Get files changed vs main
git diff --name-only origin/main...HEAD | grep '\.rs$'
# Then run mutants on those files
cargo mutants -- -f <each_file>

Full Run

If the user says "full" or "all":

cargo mutants

This is slow on a full codebase — prefer targeted runs during development.

Interpreting Results

• Killed: Test suite caught the mutation. Good.
• Survived: A mutation passed all tests — a test gap. Investigate and add a test.
• Timeout: Mutation caused an infinite loop. Usually fine — means tests do exercise that code path.
• Unviable: Mutation didn't compile. Ignored.

For each survivor, report:

1. Which function was mutated
2. What the mutation was (e.g., "replaced > with >=")
3. Which test should have caught it but didn't
4. Suggest a specific test to add

$ARGUMENTS

If provided, use as the file/module scope: cargo mutants -- -f $ARGUMENTS