stryker-agent-reporter

stryker-agent-reporterv0.3.0Apache-2.0

A Stryker reporter that writes JSON Lines a coding agent can act on directly

Install

npm install stryker-agent-reporter

• Source on GitHub
• Uses: archstrict, nukadoko
• Used by: archstrict, autospawn, finderscope, firstlight, polylinedb, solarsql

stryker-agent-reporter is a Stryker reporter for a coding agent. It writes JSON Lines, one object per line, so an agent can read the result a line at a time and filter it with grep or jq. Each surviving mutant’s line carries its location, the original and replacement text, a ready-to-apply patch, and a rerun command. The agent does not need to work any of that out again from Stryker’s own report. Two more commands, convert and gate, work from that output alone.

Features

• One line per mutant. reports/mutation/agent.jsonl starts with a run line, then one scope line per mutated file, one line per actionable mutant, and one testWithoutKills line per test that killed no mutant. Its coveredMutants counts the mutants of this run that the test reached, which separates a test that ran against mutants and killed none from a test that a narrowed --mutate never reached. A summary line comes last, so a file without one is a run that did not finish.
• Material for a fix. A survivor line carries patch, ready for git apply --unidiff-zero. It also carries rerun for its file and rerunExact for that one mutant.
• Stable keys. Each mutant’s key comes from its own source text, not its line number, so an edit elsewhere in the file keeps it. A scope line lists every key of its file, which tells a killed mutant apart from one that a narrower mutate range left out.
• Results during the run. The reporter appends each finished mutant to reports/mutation/agent.partial.jsonl, so tail -f shows survivors while Stryker still runs.
• A gate for pull requests. stryker-agent-reporter gate --since origin/main --format github checks only the changed lines and annotates them in GitHub Actions. Exit code 1 means a survivor or an uncovered mutant remains, and exit code 3 means a measurement failure, not a proven gap. With --baseline <file>, only a new survivor fails the gate.
• Saved reports. stryker-agent-reporter convert turns a saved mutation.json into the same JSON Lines.

How an agent uses it

1. Run Stryker with the agent reporter, and read agent.partial.jsonl while the run goes.
2. Select the survivors, for example with jq -c 'select(.kind=="survivor")' reports/mutation/agent.jsonl.
3. For each survivor, read original, replacement, and patch, make the change, then run its rerunExact command to test that mutant again.
4. In CI, run gate --since, so a pull request fails only on mutants in the lines it changed.

Getting started

npm install --save-dev stryker-agent-reporter

Add the agent reporter to the Stryker config. Stryker’s default plugins loads only @stryker-mutator/*, so name this package too.

{
  "reporters": ["clear-text", "agent"],
  "plugins": ["@stryker-mutator/*", "stryker-agent-reporter"]
}