Bugfix FXIOS-12036 [Homepage] scroll to top on opening a new homepage (backport #26210) (#26214)

Bugfix FXIOS-12036 [Homepage] scroll to top on opening a new homepage (#26210)

(cherry picked from commit 48fcd50)

Co-authored-by: Cyndi Chin <[email protected]>

Author: mergify[bot]

firefox-ios/Client/Frontend/Home/Homepage Rebuild/HomepageViewController.swift

@@ -295,10 +295,11 @@ final class HomepageViewController: UIViewController,
             state: state,
             jumpBackInDisplayConfig: getJumpBackInDisplayConfig()
         )
-        // FXIOS-11523 - Trigger impression when user opens homepage view new tab
+        // FXIOS-11523 - Trigger impression when user opens homepage view new tab + scroll to top
         if homepageState.shouldTriggerImpression {
             alreadyTrackedItems.removeAll()
             trackVisibleItemImpressions()
+            scrollToTop()
         }
     }
 

firefox-ios/firefox-ios-tests/Tests/ClientTests/Frontend/Homepage Rebuild/HomepageViewControllerTests.swift

@@ -277,6 +277,29 @@ final class HomepageViewControllerTests: XCTestCase, StoreTestUtility {
         XCTAssertEqual(actionCalled.windowUUID, .XCTestDefaultUUID)
     }
 
+    func test_newState_didSelectedTabChangeToHomepageAction_forScrollToTop_setsCollectionViewOffsetToZero() {
+        let mockStatusBarScrollDelegate = MockStatusBarScrollDelegate()
+        let subject = createSubject(statusBarScrollDelegate: mockStatusBarScrollDelegate)
+        let newState = HomepageState.reducer(
+            HomepageState(windowUUID: .XCTestDefaultUUID),
+            GeneralBrowserAction(
+                windowUUID: .XCTestDefaultUUID,
+                actionType: GeneralBrowserActionType.didSelectedTabChangeToHomepage
+            )
+        )
+
+        guard let collectionView = subject.view.subviews.first(where: {
+            $0 is UICollectionView
+        }) as? UICollectionView else {
+            XCTFail()
+            return
+        }
+
+        subject.newState(state: newState)
+
+        XCTAssertEqual(collectionView.contentOffset, .zero)
+    }
+
     private func createSubject(statusBarScrollDelegate: StatusBarScrollDelegate? = nil) -> HomepageViewController {
         let notificationCenter = MockNotificationCenter()
         let themeManager = MockThemeManager()