Don't require an argument for nf-core schema lint

[sersorrel]

nf-core lint and nf-core modules lint can both be called with no arguments, but nf-core schema lint requires that you pass the path to the schema. Since this will often just be at ./nextflow_schema.json, defaulting to that reduces the length of the invocation in the common case and makes the usage of all three lint commands more consistent.

I'm not 100% sure of how click.Path works – is just providing a string as the default here correct? should I be using some other Path type?

Also I don't know how the fancy images in the readme get generated, I'm hoping based on looking at the commit history for them that there's some magic github action that will kick in once I open the PR...

Fixes #1838

PR checklist

• This comment contains a description of changes (with reason)
• CHANGELOG.md is updated

[codecov]

Codecov Report

Merging #2225 (8a9569b) into dev (8a9569b) will not change coverage.
The diff coverage is n/a.

❗ Current head 8a9569b differs from pull request most recent head b4e22d3. Consider uploading reports for the commit b4e22d3 to get more accurate results

@@           Coverage Diff           @@
##              dev    #2225   +/-   ##
=======================================
  Coverage   72.88%   72.88%           
=======================================
  Files          78       78           
  Lines        8372     8372           
=======================================
  Hits         6102     6102           
  Misses       2270     2270           

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[awgymer]

This all looks good to me. The default works fine as a string in my testing. Indeed I believe click.Path actually returns as string to the command and is just a class for the sake of performing some checks.

Do we need to add a test for this command that uses the default?

[sersorrel]

I can't see any existing tests for nf-core schema lint, so I added a couple of them alongside the existing CLI tests – let me know if there are already tests and I just missed them

[Aratz]

LGTM 👍

[Aratz]

Remember to update the changelog though ;)

[github-actions]

Python linting (black) is failing

To keep the code consistent with lots of contributors, we run automated code consistency checks.
To fix this CI test, please run:

• Install black: pip install black
• Fix formatting errors in your pipeline: black .

Once you push these changes the test should pass, and you can hide this comment 👍

We highly recommend setting up Black in your code editor so that this formatting is done automatically on save. Ask about it on Slack for help!

Thanks again for your contribution!