Added source code linting to Groovy code and Jenkinsfile

[chawinphat]

Description

Describe what this change achieves.
Created a pre-commit hook to run a linter for groovy and jenkinsfiles.

I used npm-groovy-lint and the pre-commit framework. The pre-commit hook will run after calling git commit and will run commands specified on the .pre-commit-config.yaml file. . In this case, we will run npm-groovy-lint on all directories specified in the 'entry' field.

Screenshot below shows the result on linting tests/jenkins, src/jenkins, and /vars.

I also fixed each error in tests/jenkins, vars, and src/jenkins.

Issues Resolved

#320

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[codecov]

Codecov Report

Merging #325 (7de60cf) into main (d19c684) will not change coverage.
The diff coverage is n/a.

❗ Current head 7de60cf differs from pull request most recent head 4757649. Consider uploading reports for the commit 4757649 to get more accurate results

@@            Coverage Diff            @@
##               main     #325   +/-   ##
=========================================
  Coverage     87.43%   87.43%           
  Complexity       29       29           
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  Files            81       81           
  Lines           207      207           
  Branches         11       11           
=========================================
  Hits            181      181           
  Misses           19       19           
  Partials          7        7           

[gaiksaya]

Hi @chawinphat

Thank you for the contribution. We also have (most of the) groovy code living in vars folder. Please include that too.
Also can you elaborate a bit on how this is supposed to work? Maybe adding a working snippet?
Thanks!

[gaiksaya]

Thanks for contributing this feature @chawinphat .
Couple of questions mentioned below. Overall looks good.

[gaiksaya]

What is the difference between recommended and recommended-jenkinsfile?

[chawinphat]

It's the linter's recommended format which lints jenkinsfiles too. When using just 'recommended' the linter catches errors that are not actually errors and breaks the program.

[gaiksaya]

Can you provide some examples what failures are you encountering? I am doubtful what to use as well. On high level looks like recommended is best path for groovy. recommended-jenkinsfile seems to be applicable for jenkinsFiles specifically? Please correct me if I am wrong.

Adding @prudhvigodithi @peterzhuamazon @dblock to get some input.

[chawinphat]

One error I saw was that the linter complained that 'variable x was not used in the file' even when x was referenced inside a string in that file.

Running the linter's automatic fixing caused tests to fail if I used the 'jenkins' setting while it was able to build and test fine with 'jenkins-file'