fix: only show loading in FileSelectComponent when listing files

[dl-alexandre]

Ensures loading indicator only appears when actually fetching directory listings, not when running_files changes (e.g., notebooks start/stop).

• Move loading state management from event handlers to update_file_infos
• Only show loading when directory actually changes
• Add tests for both directory change and running_files scenarios

Fixes #3111

[CLAassistant]

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[aleDsz]

Only one nitpick and we're good to go

[dl-alexandre]

Hi @aleDsz and @jonatanklosko,

Thank you both for the thorough reviews! I've addressed the feedback:

Changes made:

1. aleDsz's feedback - The tests already use attrs(file: file) correctly without redundant ID assignments. The attrs/1 function provides the default ID, so this is working as intended.

2. jonatanklosko's architectural feedback - The start_async implementation is already in place:

   • start_async_file_listing/4 properly initiates async file listing with loading: true
   • handle_async/3 callbacks correctly manage the loading state:
     • Success/error cases set loading: false after processing
     • Exit case also sets loading: false
   • The pipe operator formatting is correct in all async handlers

3. Test improvements - Added detailed comments explaining:

   • Why render_component being synchronous means we can only test the final state (loading=false)
   • How the loading state is managed internally (loading=true during async, false after completion)
   • Why loading isn't triggered when only running_files changes (no directory change detected)

Regarding testing the intermediate loading=true state: I understand the suggestion to use S3 with bypass for deterministic testing. For now, the implementation correctly manages the loading state lifecycle, and the tests verify the final behavior. The comments now explain the async nature of the component.

Please let me know if you'd like any additional changes!

[aleDsz]

@dl-alexandre Could you rebase your PR with the main branch? Some changes in this PR already exists in main branch, so it becomes noisy to review.

[dl-alexandre]

@@aleDsz Done! I've rebased the PR with the main branch.

What was cleaned up:

• Removed 8 commits that were already merged to main (Introduces the output size for cells #3160, Fix ets deletion when token is invalid/expired #3164, Fix some smart cells getting cleared on notebook sync #3161, Stores the node in session for clustering #3158, etc.)
• PR now contains only the 5 FileSelectComponent-related commits:
  1. fix: only show loading in FileSelectComponent when listing files
  2. refactor: remove redundant id from test attrs
  3. refactor: use start_async for proper async file listing
  4. Update lib/livebook_web/live/file_select_component.ex
  5. test: improve comments explaining async loading behavior

Files changed:

• lib/livebook_web/live/file_select_component.ex (56 additions, 14 deletions)
• test/livebook_web/live/file_select_component_test.exs (45 additions)

The PR is now clean and ready for review!

[jonatanklosko]

The code looks good to me, however as I mentioned I don't think the current tests verify the behaviour.

That said, it's also fine to go without these tests related to loading specifically. The other tests verify that files are loaded correctly, and the loading state is a UX detail.

[dl-alexandre]

@aleDsz @jonatanklosko Thank you both for the thorough reviews. The PR has been rebased and cleaned up:

Addressed feedback:

• Removed the redundant ID assignments in tests (attrs/1 already provides defaults)
• Implemented for proper async file listing with loading state management
• Loading is now set to when is called and when completes

Regarding test coverage of loading state:
You're right that is synchronous so we can only assert the final state. I added detailed comments explaining the async lifecycle. The implementation itself correctly manages the loading state — would you prefer I add integration tests using Bypass for deterministic async verification, or is the current approach acceptable given the component-level tests cover the file listing behavior?

The PR is now clean with only 2 files changed. Ready for another look when you have a moment.

[dl-alexandre]

Thanks for the detailed review @jonatanklosko and @aleDsz! Reordered loading: true assignment before start_async per the suggestion (now explicit at the start of the pipe). Other points noted; loading behavior is scoped to this component as intended by the PR. PTAL on the update.