watch: add CLI flag to preserve output

[debadree25]

Added a --preserve-output flag to watch mode
Fixes: #45713

[tniessen]

Is clearing the terminal really a good default choice? Doesn't that potentially take away error messages etc., depending on the terminal host? What if stdout is not a TTY?

[debadree25]

Is clearing the terminal really a good default choice? Doesn't that potentially take away error messages etc., depending on the terminal host? What if stdout is not a TTY?

I guess you are right it could be inconvenient to have to add a flag in order to preserve the output, if suggested i could change the logic to preserving the output by default

[debadree25]

Have added the relevant tests and refactored the option flag, I believe its ready for a review

Thank You!

[MoLow]

No strong opinion regarding what the default to be, but I do think we should support clearing

[debadree25]

@MoLow @tniessen any further thoughts on how we could progress on this? i guess making the default to not clear the screen could be a good idea, can refactor the code accordingly

[tniessen]

i guess making the default to not clear the screen could be a good idea, can refactor the code accordingly

I don't use watch mode and I am not familiar with the current implementation. cc'ing those who approved #44366: @aduh95 @benjamingr

[aduh95]

I think it makes sense to have an option for this, I think changing the default can be done in a separate PR – this PR also adds --no-watch-preserve-output flag so if we want to switch the default it's already a step in the right direction.
Two nits:

[debadree25]

I think it makes sense to have an option for this, I think changing the default can be done in a separate PR – this PR also adds --no-watch-preserve-output flag so if we want to switch the default it's already a step in the right direction. Two nits:

understood so if changing the default is needed we can just update the option name in a separate PR?

[aduh95]

Would you be able to change the first commit message to use watch subsystem instead of lib,src? I suggest something like watch: add CLI flag to preserve output. If not it's OK it can be done by whoever lands this PR, or I can do it if you prefer.

[aduh95]

understood so if changing the default is needed we can just update the option name in a separate PR?

Yes, we would need to update the docs, and change the value from false to true in src/node_options.h, and voilà.

[debadree25]

Understood, rebasing the commit

[debadree25]

@aduh95 have rebased the commit

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/48410/

[nodejs-github-bot]

Commit Queue failed

- Loading data for nodejs/node/pull/45717
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----------------------------------- PR info ------------------------------------
Title      watch: add CLI flag to preserve output (#45717)
Author     Debadree Chatterjee  (@debadree25)
Branch     debadree25:ft/add-preserve-output-flag -> nodejs:main
Labels     c++, author ready, needs-ci, commit-queue-squash
Commits    12
 - watch: add CLI flag to preserve output
 - test: add test for preserve-output
 - lib,src: fixed linting issues
 - lib,src: refactor naming of flag
 - doc: add option to doc
 - doc: fix option ordering
 - test: remove unnecessary console
 - lib: store clear output in a const
 - doc: update content
 - lib: refactor writing output
 - doc: update content
 - doc: update content
Committers 1
 - Debadree Chatterjee 
PR-URL: https://github.com/nodejs/node/pull/45717
Fixes: https://github.com/nodejs/node/issues/45713
Reviewed-By: Antoine du Hamel 
Reviewed-By: Moshe Atlow 
------------------------------ Generated metadata ------------------------------
PR-URL: https://github.com/nodejs/node/pull/45717
Fixes: https://github.com/nodejs/node/issues/45713
Reviewed-By: Antoine du Hamel 
Reviewed-By: Moshe Atlow 
--------------------------------------------------------------------------------
   ℹ  This PR was created on Fri, 02 Dec 2022 18:03:15 GMT
   ✔  Approvals: 2
   ✔  - Antoine du Hamel (@aduh95) (TSC): https://github.com/nodejs/node/pull/45717#pullrequestreview-1212730014
   ✔  - Moshe Atlow (@MoLow): https://github.com/nodejs/node/pull/45717#pullrequestreview-1212754092
   ✔  Last GitHub CI successful
   ℹ  Last Full PR CI on 2022-12-11T17:46:19Z: https://ci.nodejs.org/job/node-test-pull-request/48410/
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   ✔  Last Jenkins CI successful
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   ✔  No git cherry-pick in progress
   ✔  No git am in progress
   ✔  No git rebase in progress
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- Bringing origin/main up to date...
From https://github.com/nodejs/node
 * branch                  main       -> FETCH_HEAD
✔  origin/main is now up-to-date
- Downloading patch for 45717
From https://github.com/nodejs/node
 * branch                  refs/pull/45717/merge -> FETCH_HEAD
✔  Fetched commits as 22dc987fde29..dafdb5827c39
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[main 23433fbbd4] watch: add CLI flag to preserve output
 Author: Debadree Chatterjee 
 Date: Fri Dec 2 23:26:43 2022 +0530
 3 files changed, 9 insertions(+), 3 deletions(-)
[main cb41045603] test: add test for preserve-output
 Author: Debadree Chatterjee 
 Date: Sat Dec 3 00:27:34 2022 +0530
 1 file changed, 26 insertions(+)
[main 7138359251] lib,src: fixed linting issues
 Author: Debadree Chatterjee 
 Date: Sat Dec 3 00:27:59 2022 +0530
 2 files changed, 5 insertions(+), 3 deletions(-)
[main 41fc6d8488] lib,src: refactor naming of flag
 Author: Debadree Chatterjee 
 Date: Sat Dec 3 01:02:40 2022 +0530
 4 files changed, 7 insertions(+), 7 deletions(-)
[main 6b6b34a473] doc: add option to doc
 Author: Debadree Chatterjee 
 Date: Sat Dec 3 01:02:59 2022 +0530
 1 file changed, 9 insertions(+)
[main d6020e08a1] doc: fix option ordering
 Author: Debadree Chatterjee 
 Date: Sat Dec 3 01:10:07 2022 +0530
 1 file changed, 1 insertion(+), 1 deletion(-)
[main 7f49b18f72] test: remove unnecessary console
 Author: Debadree Chatterjee 
 Date: Sat Dec 3 01:45:10 2022 +0530
 1 file changed, 1 deletion(-)
[main b16f74385c] lib: store clear output in a const
 Author: Debadree Chatterjee 
 Date: Sat Dec 3 23:14:55 2022 +0530
 1 file changed, 2 insertions(+), 1 deletion(-)
[main d52b3f463f] doc: update content
 Author: Debadree Chatterjee 
 Date: Sun Dec 11 22:44:53 2022 +0530
 1 file changed, 1 insertion(+), 1 deletion(-)
[main 56a8f68c6e] lib: refactor writing output
 Author: Debadree Chatterjee 
 Date: Sun Dec 11 22:45:42 2022 +0530
 1 file changed, 2 insertions(+), 4 deletions(-)
[main 0185245962] doc: update content
 Author: Debadree Chatterjee 
 Date: Sun Dec 11 23:00:25 2022 +0530
 1 file changed, 1 insertion(+), 1 deletion(-)
[main 00b1a164a5] doc: update content
 Author: Debadree Chatterjee 
 Date: Sun Dec 11 23:00:44 2022 +0530
 1 file changed, 1 insertion(+), 1 deletion(-)
   ✔  Patches applied
There are 12 commits in the PR. Attempting to fixup everything into first commit.
[main 885f461251] watch: add CLI flag to preserve output
 Author: Debadree Chatterjee 
 Date: Fri Dec 2 23:26:43 2022 +0530
 5 files changed, 43 insertions(+), 2 deletions(-)
   ✖  Git found no trailers in the original commit message, but 'Fixes: https://github.com/nodejs/node/issues/45713' is present and should be a trailer.

https://github.com/nodejs/node/actions/runs/3670813383

[aduh95]

Landed in 79a977a, thanks for the contribution 🎉

[debadree25]

Landed in 79a977a, thanks for the contribution 🎉

Thank you so much! thank you for your time too!

[benjamingr]

I don't like adding these many flags to Node's core executable. I would prefer it if this was an option to the existing flags.

The actual changes lgtm

[tniessen]

@benjamingr Agreed. Maybe an interface similar to python's -m would be helpful, where mode-specific options are only parsed after the mode has been selected. Especially for the test runner and for watch mode, this could be relevant.