Discover Suite with constructor with default parameter

[Robert Elliot]

Hi,

I have a Suite with a constructor with default arguments as so:

class MyTests(environmentFactory: FixtureFactory[Environment] = EnvironmentFactory()) extends fixture.FunSuite {

  override type FixtureParam = Environment

  test("hello world") { environment =>
    ...
  }

  override protected def withFixture(test: OneArgTest): Outcome = {
    environmentFactory.using { environment =>
      test.apply(environment)
    }
  }

}

object EnvironmentFactory {
  def apply(): FixtureFactory[Environment] = ???
}

I want this because the environment factory may optionally be a pool of environments, and I'd like to manage that pool at a higher level when running all my tests but use a non-pooled default version when running one test.

Unfortunately the scalatest SuiteDiscoveryHelper.isAccessibleSuite method doesn't find it as a Suite because Java reflection doesn't see it as having a no args constructor. Is there anything that could be done using Scala reflection to allow for this case? I've had a quick look at the Scala reflection API and it wasn't immediately obvious...

Wondering really if it's worth raising an issue for this or not, particularly as I don't know how to fix it myself! I'm sort of hoping that if it worked in the scalatest runner it would also work inside IntelliJ (which also refuses to run this class as a test standalone).

Thanks,

Rob

[Bill Venners]

Hi Robert,

The way to achieve what you want is to not use default arguments. Just use two overloaded constructors instead, one that takes the environmentFactory (the primary constructor) and one that takes no arguments (an auxiliary constructor). The auxiliary then passes the EnvironmentFactory to the primary. Something like:

class MyTests(environmentFactory: FixtureFactory[Environment]) extends fixture.FunSuite {

  def this() = this(EnvironmentFactory())

  ...

This way MyTests does have a no-arg constructors, so it can be discovered by ScalaTest (and sbt, etc.).

Bill

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[Robert Elliot]

Thanks Bill, and yes, that works great.

Just another scala gotcha I suppose - I'd assumed that the default arguments version was just a shorthand for the version with two explicit constructors, but evidently not!

Cheers,

Rob