[fs] Expose an experimental fs module with an open function and a File abstraction (1/3)

[oleiade]

What?

This Pull Request aims to address #3142 and is the first step towards introducing a fs module to k6 as tracked by #3141.

In this Pull Request we:

• introduce a k6/experimental/fs module
• exposing:
  • an open function that ensures the file is loaded in memory once, and returns a File object to the user.
  • a File object abstraction to the JS runtime: which currently supports a single Stat method and exposes a Name property.
  • a FileInfo abstraction that is returned by the File.stat method and exposes the name (basename) of the file and its size as properties to the JS runtime.

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have run linter locally (make ci-like-lint) and all checks pass.
• I have run tests locally (make tests) and all tests pass.
• I have commented on my code, particularly in hard-to-understand areas.

Related PR(s)/Issue(s)

closes #3142

ref #3141
ref #2974

[oleiade]

🗣️ the "convert to draft" button doesn't seem to work at the moment...

[codecov-commenter]

Codecov Report

Attention: 66 lines in your changes are missing coverage. Please review.

Comparison is base (d26bde8) 73.37% compared to head (9826b91) 73.31%.

❗ Current head 9826b91 differs from pull request most recent head d48fb67. Consider uploading reports for the commit d48fb67 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3165      +/-   ##
==========================================
- Coverage   73.37%   73.31%   -0.06%     
==========================================
  Files         261      266       +5     
  Lines       19779    19988     +209     
==========================================
+ Hits        14513    14655     +142     
- Misses       4369     4423      +54     
- Partials      897      910      +13     

Flag	Coverage Δ
ubuntu	73.26% <68.42%> (-0.05%)	⬇️
windows	73.17% <68.42%> (-0.06%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
js/jsmodules.go	100.00% <100.00%> (ø)
js/modules/k6/experimental/fs/file.go	100.00% <100.00%> (ø)
js/modules/k6/experimental/fs/errors.go	80.00% <80.00%> (ø)
js/modules/k6/experimental/fs/cache.go	55.55% <55.55%> (ø)
js/modules/k6/experimental/fs/errors_gen.go	9.09% <9.09%> (ø)
js/modules/k6/experimental/fs/module.go	71.09% <71.09%> (ø)

... and 1 file with indirect coverage changes

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[imiric]

Good first step @oleiade! 👏

Just have some minor and nitpicky comments/questions.

[oleiade]

I have created #3454 to factor fsext.Abs out of this PR. I will remove the relevant commit and rebase on master once #3454 is merged 🤞🏻

[oleiade]

Heads-up that I intend to clean up the history of the PR once I get approvals, so that we can create a merge commit 👍🏻

[codebien]

🎉 👏

[olegbespalov]

👍

[oleiade]

🎉 I'll go ahead and squash and merge instead of making a merge commit as I realized that some of the changes applied as part of the PR review apply to content that was part of children's PRs, and that would make the whole branch cleanup quite nasty (if not impossible).