If the passed testName is None, this trait's implementation of this method will for each test name returned by testNames, invoke newInstance to get a new instance of this Suite, and call run on it, passing in the test name wrapped in a Some. If the passed testName is defined, this trait's implementation of this method will simply forward all passed parameters to super.run. If the invocation of either newInstance on this Suite or run on a newly created instance of this Suite completes abruptly with an exception, then this runTests method will complete abruptly with the same exception.

This trait's implementation of runTests invokes this method to create a new instance of this Suite for each test. This trait's implementation of this method uses reflection to call this.getClass.newInstance. This approach will succeed only if this Suite's class has a public, no-arg constructor. In most cases this is likely to be true, because to be instantiated by ScalaTest's Runner a Suite needs a public, no-arg constructor. However, this will not be true of any Suite defined as an inner class of another class or trait, because every constructor of an inner class type takes a reference to the enclosing instance. In such cases, and in cases where a Suite class is explicitly defined without a public, no-arg constructor, you will need to override this method to construct a new instance of the Suite in some other way.

Here's an example of how you could override newInstance to construct a new instance of an inner class:

   import org.scalatest.Suite
  
   class Outer {
     class InnerSuite extends Suite with OneInstancePerTest {
       def testOne() {}
       def testTwo() {}
       override def newInstance = new InnerSuite
     }
   }