[wp-trac] [WordPress Trac] #49532: Clicking "preview" multiple times on a post causes an identical autosave revision to be created and destroyed repeatedly

[WordPress Trac]

#49532: Clicking "preview" multiple times on a post causes an identical autosave
revision to be created and destroyed repeatedly
-------------------------------------------------+-------------------------
 Reporter:  inwerpsel                            |       Owner:
                                                 |  adamsilverstein
     Type:  defect (bug)                         |      Status:  assigned
 Priority:  normal                               |   Milestone:  6.2
Component:  Revisions                            |     Version:  5.4
 Severity:  normal                               |  Resolution:
 Keywords:  has-patch needs-testing dev-         |     Focuses:  rest-api,
  feedback early has-unit-tests                  |  performance
-------------------------------------------------+-------------------------
Changes (by ironprogrammer):

 * keywords:
     has-patch reporter-feedback needs-testing dev-feedback early has-unit-
     tests
     => has-patch needs-testing dev-feedback early has-unit-tests


Comment:

 Thanks for the latest updates to this, @adamsilverstein and @mukesh27! The
 steps below were adapted to include confirmation of autosave revision
 record changes.

 == Test Report
 Patch tested: https://github.com/WordPress/wordpress-develop/pull/3794
 👍🏻

 === Steps to Reproduce or Test
 1. Create a new post.
 2. Enter a post title, press Return or move the cursor to the block
 inserter, and publish the post. **Make note of the post's ID.**
 3. Do not make any changes to the post. Click ''Preview > Preview in new
 tab''.
 4. 🐞 Observe that:
   - In browser dev tools that the request to `/wp-
 json/wp/v2/posts/{id}/autosaves?_locale=user` resulted in an HTTP 200
 (okay) response. The response body contains details about the new autosave
 revision. **Make note of the autosave's post ID.**
   - In the database an autosave revision record was created for the post
 (where `post_parent` matches the post's ID, and the `post_name` is
 formatted as "{post_parent}-autosave-v1").
 5. Repeat Step 3.
 6. 🐞 Observe that:
   - In dev tools the new request to `/wp-
 json/wp/v2/posts/{id}/autosaves?_locale=user` resulted in an HTTP 400
 (error) response. The response body contains the code
 `rest_autosave_no_changes`.
   - In the database the autosave revision record was **deleted**.
 7. Repeat Step 3.
 10. 🐞 Observe that:
   - In dev tools the new request to `/wp-
 json/wp/v2/posts/{id}/autosaves?_locale=user` resulted in an HTTP 200
 (okay) response, with details about a new autosave revision. **Note that
 the autosave's post ID is new.**
   - In the database a **new** autosave revision record was created for the
 post.

 === Expected Results
 When reproducing the bug:
 - ❌ When there have been no changes to the post, previewing the post
 causes a new autosave to be created.
 - ❌ If an autosave existed, previewing the post causes the autosave to be
 deleted.
 - ❌ Subsequent previews continue to create new and then delete autosave
 records when no changes have been made.

 When testing a patch:
 - ✅ When there have been no changes to the post, previewing the post
 should not create a new autosave.
 - ✅ If the post is changed, previewing should create an autosave, or
 update the existing autosave if it exists.
 - ✅ Subsequent previews should not create a new autosave when no changes
 have been made.

 === Environment
 - Hardware: MacBook Pro Apple M1 Pro
 - OS: macOS 12.6.2
 - Browser: Safari 16.2
 - Server: nginx/1.23.3
 - PHP: 7.4.33
 - WordPress: 6.2-alpha-54642-src

 === Actual Results
 When reproducing the bug:
 - ❌ Before patching, testing matched the Expected Results above. 👍🏻

 When testing a patch:
 - ✅ After patching, previewing the unedited post did not create an
 autosave.
 - ✅ When the post was modified, previewing the post created an autosave,
 or updated the existing autosave record.
 - ✅ Clicking preview multiple times did not alternate between creating
 and deleting new autosave records in the database.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/49532#comment:25>
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