Access to output channels of unnamed/implicit workflow

[birnbera]

Hi @lukfor, as always, thanks for creating and maintaining this great tool.

I only just realized this is a feature in Nextflow, but unnamed workflows can also have main and emit blocks, just not take (since there's nothing upstream to pass inputs to it). In nf-test, currently I believe there's no mechanism inside a nextflow_pipeline test to access those channels, e.g., for a snapshot, which would be super helpful for end-to-end testing. If you try to access workflow.out.<whatever>, you get the error message:

  groovy.lang.MissingPropertyException: No such property: out for class: com.askimed.nf.test.lang.WorkflowMeta
  Possible solutions: stdout

This feature request is not critical since there is a partial workaround by snapshotting directly for outputDir, but it would be a useful improvement.