Testing for -h is throwing strange errors

[hrj]

Firstly, thanks for this useful library!

We have been using scallop in the abandon project for a long time, and it works fine. But when we tried to add a test case for the "-h" option, we are getting strange errors from scalatest.

Please see this PR.

Any idea what's going on? Is the output stream being closed prematurely?

[Rogach]

I traced the error to this line: https://github.com/hrj/abandon/blob/master/base/src/main/scala/co/uproot/abandon/Config.scala#L19

Help and Version are not subclasses of ScallopException, they are subclasses of ScallopResult. So the match statement did not catch them, instead forwarding to super.onError - which prints help and calls sys.exit(0), killing the forked process and closing the streams.

Adding separate catch clause for Help fixed the failing test. Also, if you want to retain default behavior for help and version, you should take a look at original implementation of onError: https://github.com/scallop/scallop/blob/develop/src/main/scala/org.rogach.scallop/ScallopConf.scala#L403

Alternative way will be to forbid sys.exit for the time of this test execution, as we do when testing scallop: https://github.com/scallop/scallop/blob/develop/src/test/scala/CapturingTest.scala#L24

By the way, your colleague is right - only --help is created by default, -h needs to be specified explicitly.

[hrj]

Thanks a lot for the detailed response. We will fixup the onError implementation in abandon. Closing this issue in the meanwhile.