Report files

Besides what it prints, a run writes its results as files, for tools and for reading later: a report viewer, a dashboard, a badge, a code-quality plugin. Every run writes them except a run of one mutant (--only, and so verify and explain), which says nothing about the rest. The summary’s Reports line lists the files it wrote.

Formats

Kind	File	What it is
`json`	`mutation.json`	The open mutation-testing report schema, version 2, which report viewers, dashboards and badges read.
`html`	`mutation.html`	The same report in the schema’s own viewer. Everything is in the one file, so it opens from disk with no network.
`xml`	`mutations.xml`	The `mutations.xml` format that many build-server and code-quality plugins read.

json and html are written unless you choose otherwise.

Where they go

Build	Directory
Gradle	`build/mutastic/`, or `build/mutastic/<module>/` for a module (`:data` → `build/mutastic/data/`)
Maven	the module’s own `target/mutastic/`

The same goes for a run from the command line and from either build plugin. A file given a path of its own goes there instead, relative to the project’s directory.

Choosing which

--report=KIND[:PATH] names one report. Given at all, it replaces the defaults, so name each one you want; it can be given more than once.

--report=xml writes only mutations.xml.
--report=json --report=xml writes mutation.json and mutations.xml.
--report=json:reports/mutation.json writes the JSON report to reports/mutation.json.
--report=none writes nothing.

From a build plugin, reports takes the same values as a list, on the command line or in the build file:

./gradlew mutasticRun -Pmutastic.reports=json,xml

mutastic {
    reports = listOf("json", "xml")
}

mvn mutastic:run -Dmutastic.reports=json,xml

<configuration>
  <reports>
    <report>json</report>
    <report>xml</report>
  </reports>
</configuration>

mutastic run --report=json --report=xml

A list on the command line replaces the build file’s. See --report for the option itself.