Checkstyle

Performs quality checks on Java source files using Checkstyle and generates reports from these checks.

CheckstyleModule

To use this plugin in a Java/Scala module,

Extend mill.contrib.checkstyle.CheckstyleModule.
Define a configuration file checkstyle-config.xml.
Run the checkstyle command.

checkstyle

flags

// if an exception should be raised when violations are found
checkstyle --check

// if Checkstyle output report should be written to System.out
checkstyle --stdout

sources (optional)

// incorrect paths will cause a command failure
// checkstyle a/b

// you can specify paths relative to millSourcePath
checkstyle src/a/b

// process a single file
checkstyle src/a/B.java

// process multiple sources
checkstyle src/a/b src/c/d src/e/F.java

// process with flags
checkstyle --check --stdout src/a/b src/c/d

// process all module sources
checkstyle

Shared configuration

To share checkstyle-config.xml across modules, adapt the following example.

import mill._
import mill.contrib.checkstyle.CheckstyleModule
import mill.scalalib._

object foo extends Module {

  object bar extends MyModule
  object baz extends Module {
    object fizz extends MyModule
    object buzz extends MyModule
  }

  trait MyModule extends JavaModule with CheckstyleModule {

    override def checkstyleConfig = T {
      api.PathRef(T.workspace / "checkstyle-config.xml")
    }
  }
}

Limitations

Version 6.3 or above is required for plain and xml formats.
Setting checkstyleOptions might cause failures with legacy versions.

CheckstyleXsltModule

This plugin extends the mill.contrib.checkstyle.CheckstyleModule with the ability to generate reports by applying XSL Transformations on a Checkstyle output report.

Auto detect XSL Transformations

XSLT files are detected automatically provided a prescribed directory structure is followed.

/**
 * checkstyle-xslt
 *  ├─ html
 *  │   ├─ xslt0.xml
 *  │   └─ xslt1.xml
 *  └─ pdf
 *      ├─ xslt1.xml
 *      └─ xslt2.xml
 *
 * html/xslt0.xml -> xslt0.html
 * html/xslt1.xml -> xslt1.html
 * pdf/xslt1.xml  -> xslt1.pdf
 * pdf/xslt2.xml  -> xslt2.pdf
 */

Specify XSL Transformations manually

For a custom setup, adapt the following example.

import mill._
import mill.api.PathRef
import mill.contrib.checkstyle.CheckstyleXsltModule
import mill.contrib.checkstyle.CheckstyleXsltReport
import mill.scalalib._

object foo extends JavaModule with CheckstyleXsltModule {

    override def checkstyleXsltReports = T {
      Set(
        CheckstyleXsltReport(
          PathRef(millSourcePath / "checkstyle-no-frames.xml"),
          PathRef(T.dest / "checkstyle-no-frames.html"),
        )
      )
  }
}