custom nonEmpty mutated to isEmpty that doesn't exist

[jozic]

Summary

I have an object with method named nonEmpty, like

object QueryParams {
  def nonEmpty: QueryParams = ???
}

and call QueryParams.nonEmpty is mutated to QueryParams.isEmpty
which of course doesn't compile

Stryker4s config

default

Stryker4s environment

stryker4s 0.3.3

Your Environment

software	version(s)
Scala version	2.12
Build tool & version	maven
Operating System	linux mint 18 (ubuntu 16.04)

[hugo-vrijswijk]

Thank you for your issue report! Unfortunately, this is a known problem. The issue is that currently there is no way to distinguish if a mutation is possible, other than based on syntax. And if something goes wrong, we have no rollback process implemented (#14). As a temporary fix, you could always ignore the file to be mutated with the following stryker4s.conf:

stryker4s {
  mutate: [ "**/main/scala/**/*.scala", "!**/QueryParams.scala" ]
}

[jozic]

@hugo-vrijswijk
So my understanding is that nonEmty/isEmpty is aimed at collections, is that right?
If so, then can we also check the type before applying this mutation? Not sure how easy that is, but sounds possible, wdyt?

[hugo-vrijswijk]

It should be possible, yes! Likely either by using SemanticDB or through an experiment with TASTY. I tried a little experiment with SemanticDB a while back, but didn't get as far as I would've liked.

Ideally, we'd do both (type check and compile rollback), but that is likely a little further down the line.