Fix retain cycles in AnnouncementsDataStoreTests and GutenbergVideoUploadProcessor (#25548)

* Fix retain cycle in AnnouncementsDataStoreTests

Each of the four tests stores `subscription = store.onChange { … store.x … }`
in an instance property. The closure captures the local `store` strongly,
which is then retained by `CachedAnnouncementsStore.changeDispatcher`'s
observers dictionary, forming the cycle:

  store → changeDispatcher → observers[token] → closure → store

Without a `tearDown`, the `Receipt` only deinits when XCTest tears down the
test instance, which it defers when more tests are queued in the class —
so the cycle is observable by the end-of-test leak snapshot.

Adding `tearDown` to nil out `subscription` triggers the `Receipt.deinit`
unsubscribe path immediately and breaks the cycle.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* Fix retain cycle in GutenbergVideoUploadProcessor

The three `lazy var` properties (`videoHtmlProcessor`, `videoBlockProcessor`,
`mediaTextVideoBlockProcessor`) each construct a child processor whose
`replacer:` closure references `self` without a capture list. The child
processor is owned strongly by `self`, and the closure retained inside it
captures `self` strongly — producing three independent 2-node cycles:

  GutenbergVideoUploadProcessor
    → videoHtmlProcessor (HTMLProcessor)
      → replacer.context → captures self
        → GutenbergVideoUploadProcessor (cycle)

Switching each closure to `[weak self]` (with a `guard let self` early-out)
breaks the back-edge. By ownership, the closure is only invoked while
`self` is still alive, so the guard never trips in practice.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: amanjeetsingh150

Tests/KeystoneTests/Tests/Features/Misc/WhatsNew/AnnouncementsDataStoreTests.swift

@@ -76,6 +76,11 @@ class AnnouncementsDataStoreTests: XCTestCase {
 
     private var subscription: Receipt?
 
+    override func tearDown() {
+        subscription = nil
+        super.tearDown()
+    }
+
     /// local cache contains valid announcements
     func testLocalAnnouncementsRetrieved() {
         // Given

WordPress/Classes/ViewRelated/Gutenberg/Processors/GutenbergVideoUploadProcessor.swift

@@ -13,7 +13,8 @@ class GutenbergVideoUploadProcessor: Processor {
         self.remoteURLString = remoteURLString
     }
 
-    lazy var videoHtmlProcessor = HTMLProcessor(for: "video", replacer: { (video) in
+    lazy var videoHtmlProcessor = HTMLProcessor(for: "video", replacer: { [weak self] (video) in
+        guard let self else { return "" }
         var attributes = video.attributes
 
         attributes.set(.string(self.remoteURLString), forKey: "src")
@@ -30,8 +31,9 @@ class GutenbergVideoUploadProcessor: Processor {
         static var id = "id"
     }
 
-    lazy var videoBlockProcessor = GutenbergBlockProcessor(for: VideoBlockKeys.name, replacer: { videoBlock in
-        guard let mediaID = videoBlock.attributes[VideoBlockKeys.id] as? Int,
+    lazy var videoBlockProcessor = GutenbergBlockProcessor(for: VideoBlockKeys.name, replacer: { [weak self] videoBlock in
+        guard let self,
+            let mediaID = videoBlock.attributes[VideoBlockKeys.id] as? Int,
             mediaID == self.mediaUploadID else {
                 return nil
         }
@@ -53,8 +55,9 @@ class GutenbergVideoUploadProcessor: Processor {
         static var id = "mediaId"
     }
 
-    lazy var mediaTextVideoBlockProcessor = GutenbergBlockProcessor(for: MediaTextBlockKeys.name, replacer: { videoBlock in
-        guard let mediaID = videoBlock.attributes[MediaTextBlockKeys.id] as? Int,
+    lazy var mediaTextVideoBlockProcessor = GutenbergBlockProcessor(for: MediaTextBlockKeys.name, replacer: { [weak self] videoBlock in
+        guard let self,
+            let mediaID = videoBlock.attributes[MediaTextBlockKeys.id] as? Int,
             mediaID == self.mediaUploadID else {
                 return nil
         }