watch: fix watch args not being properly filtered

[dario-piotrowicz]

Currently the logic for filtering out watch related flags before passing them to the watch target script is flawed, as it includes any flag (starting with -) that follows a flag starting with --watch (code), this allows some watch flags to make it pass the filtering resulting in the generation of multiple watch processes which is both wasteful and can cause duplicate terminal logs (alongside other issues if the target script is side-effectful).

For example if I run

node --watch --watch index.js

the current implementation will spawn a process equivalent to:

node --watch index.js

which will then finally spawn the correct:

node index.js

Here I'm addressing the incorrect filtering so that all the watch flags are correctly filtered out (making the extra process spawning disappear)

---

Fixes #57124

[dario-piotrowicz]

Note: maybe node should error if multiple --watch flags are provided?

I did not go with such a solution because that would be a breaking change, just ignoring extra --watch flags is a non breaking change and it solves the issue at hand

If someone believes that multiple --watch flags should cause an error I would propose to first land this change right now as a patch then as a followup I can also add the stricter validation which will be included as a breaking change in the next major 🙂

[dario-piotrowicz]

And/or maybe, the erroring when multiple --watch flags are provided is part of the bigger issues of node being quite permissive with its cli flags: #57864 and could be addressed as part of that 🤔

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.27%. Comparing base (25842c5) to head (685fb31).

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #57936      +/-   ##
==========================================
- Coverage   92.26%   90.27%   -1.99%     
==========================================
  Files         325      630     +305     
  Lines      126673   186112   +59439     
  Branches    20783    36470   +15687     
==========================================
+ Hits       116869   168017   +51148     
- Misses       9576    10976    +1400     
- Partials      228     7119    +6891     

see 412 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.