Add further tests for non-working set enumeration

Signed-off-by: Claudio Cambra <developer@claudiocambra.com>

Author: claucambra

Tests/NextcloudFileProviderKitTests/EnumeratorTests.swift

@@ -1165,4 +1165,130 @@ final class EnumeratorTests: XCTestCase {
         XCTAssertEqual(observer.observedPages.first, NSFileProviderPage.initialPageSortedByName as NSFileProviderPage)
         XCTAssertEqual(observer.observedPages.count, 5)
     }
+
+    func testEmptyFolderPaginatedEnumeration() async throws {
+        // 1. Setup: remoteFolder exists in the DB but has no children.
+        // Ensure the folder itself is in the database, as the enumerator for a specific item
+        // will try to fetch its metadata.
+        remoteFolder.children = [] // Ensure it's empty for this test
+        Self.dbManager.addItemMetadata(remoteFolder.toItemMetadata(account: Self.account))
+        XCTAssertNotNil(Self.dbManager.itemMetadata(ocId: remoteFolder.identifier), "Folder metadata should be in DB for enumeration.")
+
+        let db = Self.dbManager.ncDatabase() // Strong ref for in-memory test db
+        debugPrint(db)
+        // Enable pagination in MockRemoteInterface to ensure the pagination path is taken
+        let remoteInterface = MockRemoteInterface(rootItem: rootItem, pagination: true)
+
+        // 2. Create enumerator for the empty folder with a specific pageSize.
+        let enumerator = Enumerator(
+            enumeratedItemIdentifier: NSFileProviderItemIdentifier(remoteFolder.identifier),
+            account: Self.account,
+            remoteInterface: remoteInterface,
+            dbManager: Self.dbManager,
+            pageSize: 5 // Page size can be anything, as the folder is empty
+        )
+        let observer = MockEnumerationObserver(enumerator: enumerator)
+
+        // 3. Enumerate items.
+        try await observer.enumerateItems()
+
+        // 4. Assertions.
+        // When enumerating a folder (even an empty one) with depth .targetAndDirectChildren,
+        // the folder item itself should not be returned.
+        XCTAssertEqual(observer.items.count, 0, "Should enumerate nothing.")
+
+        // For an empty folder, there's only one "page" of results (the folder itself).
+        XCTAssertEqual(observer.observedPages.count, 1, "Should be one page call for an empty folder.")
+
+        // Verify the folder's metadata in the database is up-to-date.
+        // This ensures the enumeration process also updates the target item's metadata if necessary
+        let dbFolderMetadata =
+            try XCTUnwrap(Self.dbManager.itemMetadata(ocId: remoteFolder.identifier))
+        XCTAssertEqual(
+            dbFolderMetadata.etag,
+            remoteFolder.versionIdentifier,
+            "Folder ETag should be updated in DB if changed by enumeration."
+        )
+        let storedFolderItem = Item(
+            metadata: dbFolderMetadata,
+            parentItemIdentifier: .init(rootItem.identifier),
+            account: Self.account,
+            remoteInterface: remoteInterface,
+            dbManager: Self.dbManager
+        )
+        let childItemCount = storedFolderItem.childItemCount as? Int
+        let expectedChildItemCount = remoteFolder.children.count
+        XCTAssertEqual(childItemCount, expectedChildItemCount)
+    }
+
+    func testFolderWithFewItemsPaginatedEnumeration() async throws {
+        // 1. Setup: remoteFolder with 3 children (fewer than pageSize 5).
+        // Add folder metadata to DB.
+        remoteFolder.children = []
+        for i in 0..<3 {
+            let childItem = MockRemoteItem(
+                identifier: "fewItems-child\(i)",
+                name: "child\(i).txt",
+                remotePath: remoteFolder.remotePath + "/child\(i).txt",
+                account: Self.account.ncKitAccount,
+                username: Self.account.username,
+                userId: Self.account.id,
+                serverUrl: Self.account.serverUrl
+            )
+            childItem.parent = remoteFolder
+            remoteFolder.children.append(childItem)
+        }
+        Self.dbManager.addItemMetadata(remoteFolder.toItemMetadata(account: Self.account))
+        XCTAssertNotNil(Self.dbManager.itemMetadata(ocId: remoteFolder.identifier))
+
+        let db = Self.dbManager.ncDatabase()
+        debugPrint(db)
+        let remoteInterface = MockRemoteInterface(rootItem: rootItem, pagination: true)
+
+        // 2. Create enumerator with pageSize > number of children.
+        let enumerator = Enumerator(
+            enumeratedItemIdentifier: NSFileProviderItemIdentifier(remoteFolder.identifier),
+            account: Self.account,
+            remoteInterface: remoteInterface,
+            dbManager: Self.dbManager,
+            pageSize: 5
+        )
+        let observer = MockEnumerationObserver(enumerator: enumerator)
+
+        // 3. Enumerate items.
+        try await observer.enumerateItems()
+
+        // 4. Assertions.
+        // Expected items: 0 (folder itself) + 3 children = 3 items.
+        XCTAssertEqual(observer.items.count, 3, "Should enumerate the 3 children.")
+        XCTAssertFalse(
+            observer.items.contains(where: { $0.itemIdentifier.rawValue == remoteFolder.identifier }),
+            "Folder itself should be enumerated."
+        )
+        for i in 0..<3 {
+            XCTAssertTrue(
+                observer.items.contains(where: { $0.itemIdentifier.rawValue == "fewItems-child\(i)" }),
+                "Child item fewItems-child\(i) should be enumerated."
+            )
+        }
+
+        // All items fit on one page.
+        XCTAssertEqual(
+            observer.observedPages.count,
+            1,
+            "Should be one page call as all items fit in the first page."
+        )
+
+        // Verify folder metadata in DB.
+        let dbFolderMetadata =
+            try XCTUnwrap(Self.dbManager.itemMetadata(ocId: remoteFolder.identifier))
+        XCTAssertEqual(dbFolderMetadata.etag, remoteFolder.versionIdentifier)
+        // Ensure all children are also in the DB after enumeration
+        for i in 0..<3 {
+             XCTAssertNotNil(
+                Self.dbManager.itemMetadata(ocId: "fewItems-child\(i)"),
+                "Child item fewItems-child\(i) metadata should be in DB."
+             )
+        }
+    }
 }