Change non spec errors:

- failedToResolveSubscriptionPointBecauseChannelSerialNotDefined: renamed since `channelSerial` checked first. Introduced error code used in JS - 102_110;
- failedToResolveSubscriptionPointBecauseChannelFailedToAttach: changed error code to 102_112 (roomInInvalidState), JS doesn't throw anything and just waits for channel attach event. Proposed spec for throwing an error with 102_112 code;
- noItemInResponse: changed error code to 404 and proposed spec for that;
- failedToGetPaginatedResult: renamed and added full error info taken from realtime, JS also throws error with values from realtime. Am not sure what to do with `badRequest` here, probably it's fine to leave it (or `internalServerError` maybe?);
- headersValueJSONDecodingError and jsonValueDecodingError are JSON parser errors and probably should stay with `badRequest`.

Removed unused `MessagesError` enum.

Proposed specs: ably/specification#401

Author: maratal

Sources/AblyChat/AblyCocoaExtensions/InternalAblyCocoaTypes.swift

@@ -109,10 +109,14 @@ internal protocol InternalHTTPPaginatedResponseProtocol: AnyObject, Sendable {
     var items: [JSONValue] { get }
     var hasNext: Bool { get }
     var isLast: Bool { get }
-    var statusCode: Int { get }
 
     func next() async throws(ErrorInfo) -> Self?
     func first() async throws(ErrorInfo) -> Self
+
+    var success: Bool { get }
+    var statusCode: Int { get }
+    var errorCode: Int { get }
+    var errorMessage: String? { get }
 }
 
 /// Converts a `@MainActor` callback into one that can be passed as a callback to ably-cocoa.
@@ -202,10 +206,22 @@ internal final class InternalHTTPPaginatedResponseAdapter: InternalHTTPPaginated
         underlying.isLast
     }
 
+    internal var success: Bool {
+        underlying.success
+    }
+
     internal var statusCode: Int {
         underlying.statusCode
     }
 
+    internal var errorCode: Int {
+        underlying.errorCode
+    }
+
+    internal var errorMessage: String? {
+        underlying.errorMessage
+    }
+
     internal func next() async throws(ErrorInfo) -> InternalHTTPPaginatedResponseAdapter? {
         do {
             return try await withCheckedContinuation { (continuation: CheckedContinuation<Result<InternalHTTPPaginatedResponseAdapter?, ARTErrorInfo>, _>) in

Sources/AblyChat/DefaultMessages.swift

@@ -159,7 +159,7 @@ internal final class DefaultMessages<Realtime: InternalRealtimeClientProtocol>:
                         continuation.resume(returning: .success(subscriptionPoint))
                     } else {
                         logger.log(message: "Channel is attached, but attachSerial is not defined", level: .error)
-                        continuation.resume(returning: .failure(InternalError.failedToResolveSubscriptionPointBecauseAttachSerialNotDefined.toErrorInfo()))
+                        continuation.resume(returning: .failure(InternalError.failedToResolveSubscriptionPointBecauseChannelSerialNotDefined.toErrorInfo()))
                     }
                 case .failed, .suspended:
                     let error = InternalError.failedToResolveSubscriptionPointBecauseChannelFailedToAttach(cause: stateChange.reason)
@@ -171,8 +171,4 @@ internal final class DefaultMessages<Realtime: InternalRealtimeClientProtocol>:
             }
         }.get()
     }
-
-    internal enum MessagesError: Error {
-        case noReferenceToSelf
-    }
 }

Sources/AblyChat/InternalError.swift

@@ -87,25 +87,19 @@ internal enum InternalError {
     /// Error code is `badRequest` (this is our own error, which is not specified by the spec).
     case failedToResolveSubscriptionPointBecauseMessagesInstanceGone
 
-    /// Unable to fetch `historyBeforeSubscribe` because a channel in the `ATTACHED` state has violated our expectations by its `attachSerial` not being populated, so we cannot resolve its "subscription point" per CHA-M5b.
-    ///
-    /// Error code is `badRequest` (this is not specified by the spec, which does not make it explicit that the SDK should throw an error in this scenario).
-    case failedToResolveSubscriptionPointBecauseAttachSerialNotDefined
+    /// Unable to fetch `historyBeforeSubscribe` because a channel in the `ATTACHED` state has violated our expectations by its `channelSerial` or `attachSerial` not being populated, so we cannot resolve its "subscription point" per CHA-M5b.
+    case failedToResolveSubscriptionPointBecauseChannelSerialNotDefined
 
     /// Unable to fetch `historyBeforeSubscribe` because whilst waiting for a channel to become attached per CHA-M5b in order to resolve its "subscription point".
-    ///
-    /// Error code is `badRequest` (this is not specified by the spec, which does not make it explicit that the SDK should throw an error in this scenario).
     case failedToResolveSubscriptionPointBecauseChannelFailedToAttach(cause: ErrorInfo?)
 
     /// Attempted to load a resource from the given `path`, expecting to get a single item back, but the returned `PaginatedResult` is empty.
-    ///
-    /// Error code is `badRequest` (this is not specified by the spec, which does not make it explicit that the SDK should throw an error in this scenario).
     case noItemInResponse(path: String)
 
     /// An ably-cocoa `ARTHTTPPaginatedResponse` was received with the given non-200 status code.
     ///
     /// Error code is `badRequest` (this is not specified by the spec, which does not make it explicit that the SDK should throw an error in this scenario).
-    case paginatedResultStatusCode(Int)
+    case failedToGetPaginatedResult(cause: ErrorInfo?)
 
     // Failed to decode a `HeadersValue` from a `JSONValue`.
     ///
@@ -130,9 +124,11 @@ internal enum InternalError {
     internal enum ErrorCode: Int {
         case badRequest = 40000
         case invalidArgument = 40003
+        case notFound = 40400
         case roomDiscontinuity = 102_100
         case roomReleasedBeforeOperationCompleted = 102_106
         case roomExistsWithDifferentOptions = 102_107
+        case channelSerialNotDefined = 102_110
         case roomInInvalidState = 102_112
 
         /// The ``ErrorInfo/statusCode`` that should be returned for this error.
@@ -145,7 +141,10 @@ internal enum InternalError {
                  .roomInInvalidState,
                  .roomExistsWithDifferentOptions:
                 400
-            case .roomDiscontinuity:
+            case .notFound:
+                404
+            case .roomDiscontinuity,
+                 .channelSerialNotDefined:
                 500
             }
         }
@@ -183,13 +182,13 @@ internal enum InternalError {
             .invalidArgument
         case .cannotApplyCreatedMessageEvent:
             .invalidArgument
-        case .failedToResolveSubscriptionPointBecauseAttachSerialNotDefined:
-            .badRequest
+        case .failedToResolveSubscriptionPointBecauseChannelSerialNotDefined:
+            .channelSerialNotDefined
         case .failedToResolveSubscriptionPointBecauseChannelFailedToAttach:
-            .badRequest
+            .roomInInvalidState
         case .noItemInResponse:
-            .badRequest
-        case .paginatedResultStatusCode:
+            .notFound
+        case .failedToGetPaginatedResult:
             .badRequest
         case .failedToResolveSubscriptionPointBecauseMessagesInstanceGone:
             .badRequest
@@ -286,9 +285,9 @@ internal enum InternalError {
         case .failedToResolveSubscriptionPointBecauseMessagesInstanceGone:
             op = "fetch message history from before subscription"
             reason = "Messages instance has been deallocated"
-        case .failedToResolveSubscriptionPointBecauseAttachSerialNotDefined:
+        case .failedToResolveSubscriptionPointBecauseChannelSerialNotDefined:
             op = "fetch message history from before subscription"
-            reason = "channel is attached but attachSerial is not defined"
+            reason = "channel is attached but channelSerial is not defined"
         case let .failedToResolveSubscriptionPointBecauseChannelFailedToAttach(cause):
             op = "fetch message history from before subscription"
             reason = "channel failed to attach: \(cause, default: "(nil cause)")"
@@ -301,9 +300,9 @@ internal enum InternalError {
         case let .noItemInResponse(path):
             op = "load resource"
             reason = "paginated result from path \(path) is empty"
-        case let .paginatedResultStatusCode(statusCode):
+        case let .failedToGetPaginatedResult(cause):
             op = "load resource"
-            reason = "received status code \(statusCode)"
+            reason = "reason: \(cause, default: "<no reason>")"
         case let .headersValueJSONDecodingError(error):
             op = "decode headers"
             switch error {
@@ -336,6 +335,8 @@ internal enum InternalError {
             cause
         case let .failedToResolveSubscriptionPointBecauseChannelFailedToAttach(cause):
             cause
+        case let .failedToGetPaginatedResult(cause):
+            cause
         case .jsonValueDecodingError,
              .headersValueJSONDecodingError,
              .roomExistsWithDifferentOptions,
@@ -344,15 +345,14 @@ internal enum InternalError {
              .presenceOperationRequiresRoomAttach,
              .cannotApplyCreatedMessageEvent,
              .unableDeleteReactionWithoutName,
-             .failedToResolveSubscriptionPointBecauseAttachSerialNotDefined,
+             .failedToResolveSubscriptionPointBecauseChannelSerialNotDefined,
              .roomInInvalidStateForAttach,
              .roomInInvalidStateForDetach,
              .cannotApplyMessageEventForDifferentMessage,
              .cannotApplyReactionSummaryEventForDifferentMessage,
              .sendMessageReactionEmptyMessageSerial,
              .deleteMessageReactionEmptyMessageSerial,
              .noItemInResponse,
-             .paginatedResultStatusCode,
              .failedToResolveSubscriptionPointBecauseMessagesInstanceGone:
             nil
         }

Sources/AblyChat/PaginatedResult.swift

@@ -41,9 +41,14 @@ internal final class DefaultPaginatedResult<Underlying: InternalHTTPPaginatedRes
 
     /// Convenience initializer that checks status code and decodes items from the response.
     internal convenience init(response: Underlying) throws(ErrorInfo) {
-        // TODO: We've had this check since the start of the codebase, but it's not specified anywhere; rectify this in https://github.com/ably/ably-chat-swift/issues/453
-        guard response.statusCode == 200 else {
-            throw InternalError.paginatedResultStatusCode(response.statusCode).toErrorInfo()
+        // (CHA-M6b) If the REST API returns an error, then the method must throw its `ErrorInfo` representation.
+        guard response.success else {
+            throw InternalError.failedToGetPaginatedResult(cause:
+                .init(
+                    code: response.errorCode,
+                    message: response.errorMessage ?? "<no error message in response>",
+                    statusCode: response.statusCode,
+                )).toErrorInfo()
         }
 
         let items = try response.items.map { jsonValue throws(ErrorInfo) in

Tests/AblyChatTests/Mocks/MockHTTPPaginatedResponse.swift

@@ -3,18 +3,28 @@ import Ably
 
 final class MockHTTPPaginatedResponse: InternalHTTPPaginatedResponseProtocol {
     let items: [JSONValue]
-    let statusCode: Int
     let headers: [String: String]
     let hasNext: Bool
 
+    var success: Bool
+    let statusCode: Int
+    var errorCode: Int
+    var errorMessage: String?
+
     init(
         items: [[String: JSONValue]],
+        success: Bool = true,
         statusCode: Int = 200,
+        errorCode: Int = 0,
+        errorMessage: String? = nil,
         headers: [String: String] = [:],
         hasNext: Bool = false,
     ) {
         self.items = items.map { .object($0) }
+        self.success = success
         self.statusCode = statusCode
+        self.errorCode = errorCode
+        self.errorMessage = errorMessage
         self.headers = headers
         self.hasNext = hasNext
     }