TestNG
Provides support for TestNG.
To use TestNG as test framework, you need to add it to the TestModule.testFramework property.
build.scimport mill.scalalib._
object project extends ScalaModule {
  object test extends ScalaTests {
    def testFramework = "mill.testng.TestNGFramework"
    def ivyDeps = super.ivyDeps ++ Agg(
      ivy"com.lihaoyi:mill-contrib-testng:${mill.BuildInfo.millVersion}"
    )
  }
}
You can also use the more convenient TestModule.TestNg trait.
build.scimport mill.scalalib._
object project extends ScalaModule {
  object test extends ScalaTests with TestModule.TestNg
}