Add open-to-clear UI regression test for notifications (#32)

Covers the in-app path: open an unread notification, then confirm it leaves the
Unread filter after a refresh. Validated against the seeded Docker Forgejo via
just mutating_a_classes=NotificationsUITests test-mutating-a; it fails on the
pre-fix code and passes with the fix. The merged-instance and system-notification
open paths apply the same fix but aren't reachable from this single-instance UI
harness.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Forji/ForjiUITests/NotificationsUITests.swift

@@ -49,4 +49,67 @@ final class NotificationsUITests: ForgejoUITestBase {
             }
         }
     }
+
+    // MARK: - Open-to-clear (#32)
+
+    /// Opening an unread notification marks it read on the server, so it leaves
+    /// the Unread filter on the next refresh.
+    ///
+    /// Covers the in-app NotificationsOverviewView path: the tap gesture on the
+    /// row calls markReadOnOpen, which marks the thread read with
+    /// removeFromUnread: false so the row stays put during navigation and only
+    /// drops out of Unread on the next server fetch. The multi-instance and
+    /// system-notification open paths apply the same fix but aren't reachable
+    /// from this single-instance harness.
+    ///
+    /// Sorts after testNotifications and opens whichever unread row is first
+    /// rather than a fixed one, so it's unaffected by the two notifications that
+    /// test consumes (the seed leaves several more).
+    @MainActor
+    func testOpeningNotificationMarksItRead() throws {
+        loginAndWaitForHome()
+        app.tabBars.buttons["Notifications"].tap()
+
+        let notificationsList = app.collectionViews.firstMatch
+        XCTAssertTrue(notificationsList.waitForExistence(timeout: 10))
+
+        // Make sure the Unread filter is active.
+        let unreadButton = app.buttons["Unread"]
+        XCTAssertTrue(unreadButton.waitForExistence(timeout: 5))
+        unreadButton.tap()
+        XCTAssertTrue(notificationsList.waitForExistence(timeout: 10))
+
+        // Remember the first unread notification's title (the row's first text)
+        // so we can assert that specific one leaves the Unread list.
+        let firstCell = notificationsList.cells.firstMatch
+        XCTAssertTrue(firstCell.waitForExistence(timeout: 10), "Expected at least one unread notification")
+        let openedTitle = firstCell.staticTexts.firstMatch.label
+        XCTAssertFalse(openedTitle.isEmpty, "Could not read the unread notification's title")
+
+        // Open it. Navigating into the detail proves the row was tappable; the
+        // nav bar title changes away from "Notifications" once it's on screen.
+        firstCell.tap()
+        let detailNavBar = app.navigationBars.element(boundBy: 0)
+        XCTAssertTrue(detailNavBar.waitForExistence(timeout: 10), "Detail view did not open")
+        XCTAssertNotEqual(detailNavBar.identifier, "Notifications", "Did not navigate into the notification detail")
+
+        // Back to the list.
+        app.navigationBars.buttons.element(boundBy: 0).tap()
+        XCTAssertTrue(notificationsList.waitForExistence(timeout: 10))
+
+        // Force a server refresh of Unread by toggling the filter. Opening marks
+        // the thread read but keeps the row visible until the next fetch, so this
+        // round-trip is what surfaces the open-to-clear behaviour.
+        app.buttons["Read"].tap()
+        XCTAssertTrue(notificationsList.waitForExistence(timeout: 10))
+        unreadButton.tap()
+        XCTAssertTrue(notificationsList.waitForExistence(timeout: 10))
+
+        // The opened notification should no longer be under Unread.
+        let openedRow = notificationsList.staticTexts[openedTitle]
+        XCTAssertFalse(
+            openedRow.waitForExistence(timeout: 5),
+            "Opened notification \"\(openedTitle)\" should have left the Unread filter after refresh",
+        )
+    }
 }