Ignore NXF_EDGE if edge is older than latest release

[ewels]

Usage scenario

In the nf-core CI testing, we want to test pipelines with the absolute latest version of Nextflow to ensure that the pipeline will work with any upcoming releases. So we use NXF_EDGE for this. However, sometimes the edge release of Nextflow is actually older than the most recent stable release, which has nasty unintended effects. As such, we're forced to manually comment out and re-comment the NXF_EDGE variable in our CI over time as the releases come and go.

Suggest implementation

If NXF_EDGE is specified, take the latest stable release or the latest edge release - which ever is most recent.

[pditommaso]

Hi Phil, this is expected. Edge is meant to be a channel parallel to stable, therefore if you are using egde, not necessarily want to update to stable

[ewels]

Feature, not a bug.. Hmm ok, any ideas how we can achieve what we're aiming for here? "Give me the latest version of Nextflow possible"

We always used to just test on the minimum required and latest stable version, but it's nice to test against the upcoming release if possible to catch things before it drops. And I'd prefer not to run every test against three Nextflow versions for every push if possible...

[pditommaso]

it's nice to test against the upcoming release if possible

Indeed. Therefore you should a test with latest stable ie.

curl get.nextflow.io | bash

and another for latest edge

export NXF_EDGE=1
curl get.nextflow.io | bash
./nextflow -self-update

[ewels]

..and again with the stated minimum version. Ok, so no way around running more CI tests then. I think we just continue to not test edge unless we have to then.