[CIS-2024, CIS-2000] Fix Channel List pagination gaps + Truncated channels moved to bottom

CHANGELOG.md

@@ -3,7 +3,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 # Upcoming
 
-### 🔄 Changed
+## StreamChat
+### 🐞 Fixed
+- Fix Channel List pagination gaps [#2420](https://github.com/GetStream/stream-chat-swift/pull/2420)
+- Fix truncated channels being moved to the bottom of the channel list [#2420](https://github.com/GetStream/stream-chat-swift/pull/2420)
 
 # [4.25.0](https://github.com/GetStream/stream-chat-swift/releases/tag/4.25.0)
 _December 15, 2022_

Sources/StreamChat/Database/DTOs/ChannelDTO.swift

@@ -84,7 +84,12 @@ class ChannelDTO: NSManagedObject {
 
         // Update the date for sorting every time new message in this channel arrive.
         // This will ensure that the channel list is updated/sorted when new message arrives.
-        let lastDate = lastMessageAt ?? createdAt
+        // Note: If a channel is truncated, the server will update the lastMessageAt to a minimum value, and not remove it.
+        // So, if lastMessageAt is nil or is equal to distantPast, we need to fallback to createdAt.
+        var lastDate = lastMessageAt ?? createdAt
+        if lastDate.bridgeDate <= .distantPast {
+            lastDate = createdAt
+        }
         if lastDate != defaultSortingAt {
             defaultSortingAt = lastDate
         }
@@ -352,6 +357,8 @@ extension ChannelDTO {
         ]
 
         request.predicate = NSCompoundPredicate(type: .and, subpredicates: subpredicates)
+        request.fetchLimit = query.pagination.pageSize
+        request.fetchBatchSize = query.pagination.pageSize
         return request
     }
 

Tests/StreamChatTests/Database/DTOs/ChannelDTO_Tests.swift

@@ -439,18 +439,42 @@ final class ChannelDTO_Tests: XCTestCase {
         }
     }
 
-    func test_defaultSortingAt_updates_whenLastMessageAtChanges() throws {
+    func test_defaultSortingAt_shouldBeEqualToLastMessageAt() throws {
         let channelId: ChannelId = .unique
-
         try database.createChannel(cid: channelId)
-
         try database.writeSynchronously {
             let channel = try XCTUnwrap($0.channel(cid: channelId))
-            channel.lastMessageAt = .unique(after: channel.lastMessageAt ?? channel.createdAt)
+            channel.lastMessageAt = .unique
         }
 
         let channel = try XCTUnwrap(database.viewContext.channel(cid: channelId))
-        XCTAssertEqual(channel.lastMessageAt, channel.defaultSortingAt)
+        XCTAssertEqual(channel.defaultSortingAt, channel.lastMessageAt)
+    }
+
+    func test_defaultSortingAt_whenMissingLastMessageAt_shouldBeEqualToCreatedAt() throws {
+        let channelId: ChannelId = .unique
+        try database.createChannel(cid: channelId)
+        try database.writeSynchronously {
+            let channel = try XCTUnwrap($0.channel(cid: channelId))
+            channel.createdAt = .unique
+            channel.lastMessageAt = nil
+        }
+
+        let channel = try XCTUnwrap(database.viewContext.channel(cid: channelId))
+        XCTAssertEqual(channel.defaultSortingAt, channel.createdAt)
+    }
+
+    func test_defaultSortingAt_whenLastMessageAtEqualDistantPast_shouldBeEqualToCreatedAt() throws {
+        let channelId: ChannelId = .unique
+        try database.createChannel(cid: channelId)
+        try database.writeSynchronously {
+            let channel = try XCTUnwrap($0.channel(cid: channelId))
+            channel.createdAt = .unique
+            channel.lastMessageAt = .distantPast.bridgeDate
+        }
+
+        let channel = try XCTUnwrap(database.viewContext.channel(cid: channelId))
+        XCTAssertEqual(channel.defaultSortingAt, channel.createdAt)
     }
 
     func test_channelPayload_nilMembershipRemovesExistingMembership() throws {
@@ -889,6 +913,18 @@ final class ChannelDTO_Tests: XCTestCase {
         XCTAssertEqual(loadedChannels.count, 1)
         XCTAssertEqual(loadedChannels.first?.cid, channel1Id.rawValue)
     }
+
+    func test_channelWithChannelListQuery_shouldUseLimitAndBatchSize() {
+        let query = ChannelListQuery(
+            filter: .and([.less(.createdAt, than: .unique), .exists(.deletedAt, exists: false)]),
+            pageSize: 25
+        )
+
+        let fetchRequest = ChannelDTO.channelListFetchRequest(query: query)
+
+        XCTAssertEqual(fetchRequest.fetchBatchSize, 25)
+        XCTAssertEqual(fetchRequest.fetchLimit, 25)
+    }
 
     func test_channelListQuery_withSorting() {
         // Create two channels queries with different sortings.