Preview of view sources

Too late for alpha5

While working on the revamp UI Patterns's contexts, I may get an idea about this.

I will give a try.

Started.

First proposal pushed. Still WIP.

TODO:

• check pipeline fails
• check feed icon rendering
• estimate performance cost of re-excecuting the view 7 times 😱
• check fatal when rendering a full entity in View row (with and without attachments)

And also, use the current state of work to:

• move some logic upstream to UI Patterns in the scope of #3608162: Tidy source contexts (or maybe a dedicated Views ticket)
• start #3533043: Expose view sources forms in SourceInterface::settingsForm() to check if we are on good track

Rebased. It works pretty well:

• ViewAttachmentAfterSource ✅ but let's check again: it sometimes print the renderable multiple time
• ViewAttachmentBeforeSource ✅ but let's check again too
• ViewExposedSource ✅
• ViewFeedIconsSource ❌
• ViewFooterSource ✅
• ViewHeaderSource ✅
• ViewMoreSource ✅
• ViewPagerSource ✅
• ViewRowsSource ✅
• ViewTitleSource ✅

This is not a real "review", it is too soon to merge, but an opportunity to discuss about the pipeline fails. The hardcoded placeholders from PreviewPanel::alterPreviewPlaceholder() ("[View] Header", "[View] Exposed"...) have been removed and the preview is now behaving the normal way, with the "[Placeholder] No preview" added by PreviewPanel::renderPreviewSources() when empty.

However, everything become "[Placeholder] No preview":

• '[View] Header' >> '[Placeholder] No preview'
• '[View] Exposed' >> '[Placeholder] No preview'
• '[View] Attachment_before' >> '[Placeholder] No preview'
• '[View] Rows' >> '[Placeholder] No preview'
• '[View] Pager' >> '[Placeholder] No preview'
• '[View] Attachment_after' >> '[Placeholder] No preview'
• '[View] More' >> '[Placeholder] No preview'
• '[View] Footer' >> '[Placeholder] No preview'
• '[View] Feed_icons' >> '[Placeholder] No preview'

So, it is not properly testable by playwright with Displaybuilder.expectBlocksAvailable() which expect a specific and unique placeholder label for each.

The solution will be to update PreviewPanel::renderPreviewSources() to print something dynamic like '[Placeholder] @source_plugin_label'

And this may also be the opportunity to the last 4 hardcoded placeholder from PreviewPanel::alterPreviewPlaceholder():

• [Placeholder] Local tasks (Tabs)
• [Placeholder] Block messages
• [Placeholder] Page title
• [Placeholder] Page content

This is extending the scope of the ticket, is it OK?

A change of preview placeholder is proposed in #3615031: UX for nesting displays in displays comprehension so probably better to have it merged before, then back to this one, then a follow up issue for views placeholder.

Ok, i take back this issue (because I have work left to do there) and i will resume once the other one is fixed.

Edit: Finally, it will be addressed in #3618072: Placeholders and real render, in Canvas and Preview

With the split, the reviews must be done following this order:

1. #3618072: Placeholders and real render, in Canvas and Preview
2. #3542796: Preview of view sources, because the MR is rebasing the previous one
3. #3618618: Preview an entity view override and a view page display on their own page, because the MR is rebasing the previous one

ooops, wrong status change.

Back to me for review.

#3618072: Placeholders and real render, in Canvas and Preview has been merged to 1.0.x. I will rebase before the review.

Feature review

OK, source previews seem to work as expected 👍

Code review

OK, except the playwright fail following the changes in #3618072: Placeholders and real render, in Canvas and Preview:

tests/src/Playwright/Tests/views.spec.ts:49:5 › Views build and render @base › Check the base display 
    Error: expect(locator).toMatchAriaSnapshot(expected) failed
    Locator: locator('.db-island-builder .db-dropzone--root')

    - - button "[View] Header"
    - - button "[View] Exposed form"
    - - button "[View] Attachment before"
    - - button "[View] Rows"
    - - button "[View] Pager"
    - - button "[View] Attachment after"
    - - button "[View] More"
    - - button "[View] Footer"
    - - button "[View] Feed icons"
    + - text: "[View] Header Empty. Configure it to make it visible. [View] Exposed form Empty. Configure it to make it visible. [View] Attachment before Empty. Configure it to make it visible. [View] Rows Empty. Configure it to make it visible. [View] Pager Empty. Configure it to make it visible. [View] Attachment after Empty. Configure it to make it visible. [View] More Empty. Configure it to make it visible. [View] Footer Empty. Configure it to make it visible. [View] Feed icons Empty. Configure it to make it visible."