Propagate request identifiers with realtime errors

Sources/FalClient/Realtime.swift

@@ -21,7 +21,7 @@ public enum FalRealtimeError: Error {
     case unauthorized
     case invalidInput
     case invalidResult(requestId: String? = nil, causedBy: Error? = nil)
-    case serviceError(type: String, reason: String)
+    case serviceError(type: String, reason: String, requestId: String? = nil)
 }
 
 extension FalRealtimeError: LocalizedError {
@@ -35,11 +35,24 @@ extension FalRealtimeError: LocalizedError {
             return NSLocalizedString("Invalid input format", comment: "FalRealtimeError.invalidInput")
         case .invalidResult:
             return NSLocalizedString("Invalid result", comment: "FalRealtimeError.invalidResult")
-        case let .serviceError(type, reason):
+        case let .serviceError(type, reason, _):
             return NSLocalizedString("\(type): \(reason)", comment: "FalRealtimeError.serviceError")
         }
     }
 }
+public extension FalRealtimeError {
+    var requestId: String? {
+        switch self {
+        case let .invalidResult(requestId, _):
+            return requestId
+        case let .serviceError(_, _, requestId):
+            return requestId
+        default:
+            return nil
+        }
+    }
+}
+
 
 typealias SendFunction = (URLSessionWebSocketTask.Message) throws -> Void
 typealias CloseFunction = () -> Void
@@ -355,7 +368,8 @@ func getError(_ message: Payload) -> FalRealtimeError? {
        // not trigger the onError callback of the client
        error != "TIMEOUT"
     {
-        return FalRealtimeError.serviceError(type: error, reason: reason)
+        let requestId = message["request_id"].stringValue ?? message["requestId"].stringValue
+        return FalRealtimeError.serviceError(type: error, reason: reason, requestId: requestId)
     }
     return nil
 }
@@ -485,3 +499,4 @@ public extension Realtime {
         )
     }
 }
+

Tests/FalClientTests/RealtimeSpec.swift

@@ -0,0 +1,44 @@
+@testable import FalClient
+import Nimble
+import Quick
+
+class RealtimeSpec: QuickSpec {
+    override class func spec() {
+        describe("Realtime error decoding") {
+            it("attaches the request id to service errors") {
+                let message: Payload = [
+                    "type": "x-fal-error",
+                    "error": "MODEL_ERROR",
+                    "reason": "failed to process",
+                    "request_id": "req-123"
+                ]
+
+                let error = getError(message)
+                guard case let .serviceError(_, _, requestId)? = error else {
+                    fail("Expected serviceError with request identifier")
+                    return
+                }
+
+                expect(requestId).to(equal("req-123"))
+                expect(error?.requestId).to(equal("req-123"))
+            }
+
+            it("leaves the request id unset when unavailable") {
+                let message: Payload = [
+                    "type": "x-fal-error",
+                    "error": "MODEL_ERROR",
+                    "reason": "failed to process"
+                ]
+
+                let error = getError(message)
+                guard case let .serviceError(_, _, requestId)? = error else {
+                    fail("Expected serviceError when decoding realtime message")
+                    return
+                }
+
+                expect(requestId).to(beNil())
+                expect(error?.requestId).to(beNil())
+            }
+        }
+    }
+}