test(sync) Add tests to run fetchSaves and fetchArchive at the same t…

PocketKit/Sources/Sync/PocketSource.swift

@@ -635,10 +635,20 @@ extension PocketSource {
     ///   - queue: The operation queue to run the task on
     ///   - completion: The completion block to execute when the operation is done. If you need to do cleanup work, you should instead do the completion work within the operation itself because they launch BackgroundTasks
     private func enqueue(operation: SyncOperation, task: SyncTask, queue: OperationQueue, completion: (() -> Void)? = nil) {
-        let persistentTask: PersistentSyncTask = PersistentSyncTask(context: space.backgroundContext)
+        let childBGContext = space.makeChildBackgroundContext()
+        let persistentTask: PersistentSyncTask = PersistentSyncTask(context: childBGContext)
         persistentTask.createdAt = Date()
         persistentTask.syncTaskContainer = SyncTaskContainer(task: task)
-        try? space.save()
+
+        // save the child context
+        try? childBGContext.performAndWait {
+            guard childBGContext.hasChanges else {
+                return
+            }
+            try childBGContext.save()
+            // then save the parent context
+            try space.save()
+        }
 
         enqueue(operation: operation, persistentTask: persistentTask, queue: queue, completion: completion)
     }

PocketKit/Tests/SyncTests/PocketSourceTests.swift

@@ -85,6 +85,36 @@ class PocketSourceTests: XCTestCase {
         )
     }
 
+    func test_fetching_from_different_threads() async {
+        sessionProvider.session = MockSession()
+
+        operations.stubFetchSaves { _, _, _, _  in
+            TestSyncOperation { }
+        }
+
+        operations.stubFetchArchive { _, _, _, _  in
+            TestSyncOperation { }
+        }
+
+        let source = subject()
+
+        let expectationToFetchSaves = expectation(description: "Fetch Saves")
+        let expectationToFetchArchive = expectation(description: "Fetch Archive")
+
+        Task {
+            source.refreshSaves {
+                expectationToFetchSaves.fulfill()
+            }
+        }
+        Task {
+            source.refreshArchive {
+                expectationToFetchArchive.fulfill()
+            }
+        }
+
+        await fulfillment(of: [expectationToFetchSaves, expectationToFetchArchive], timeout: 10)
+    }
+
     func test_refresh_addsFetchSavesOperationToQueue() {
         let session = MockSession()
         sessionProvider.session = session

PocketKit/Tests/SyncTests/Support/MockOperationFactory.swift

@@ -10,6 +10,7 @@ import SharedPocketKit
 class MockOperationFactory: SyncOperationFactory {
     private var implementations: [String: Any] = [:]
     private var calls: [String: [Any]] = [:]
+    private var lock: DispatchQueue = DispatchQueue(label: "")
 }
 
 // MARK: - fetchSaves
@@ -44,15 +45,17 @@ extension MockOperationFactory {
             fatalError("\(Self.self).\(#function) has not been stubbed")
         }
 
-        calls["fetchSaves"] = (calls["fetchSaves"] ?? []) + [
-            FetchSavesCall(
-                apollo: apollo,
-                space: space,
-                events: events,
-                initialDownloadState: initialDownloadState,
-                lastRefresh: lastRefresh
-            )
-        ]
+        lock.sync {
+            calls["fetchSaves"] = (calls["fetchSaves"] ?? []) + [
+                FetchSavesCall(
+                    apollo: apollo,
+                    space: space,
+                    events: events,
+                    initialDownloadState: initialDownloadState,
+                    lastRefresh: lastRefresh
+                )
+            ]
+        }
 
         return impl(apollo, space, events, initialDownloadState)
     }
@@ -98,15 +101,17 @@ extension MockOperationFactory {
             fatalError("\(Self.self).\(#function) has not been stubbed")
         }
 
-        calls["fetchArchive"] = (calls["fetchArchive"] ?? []) + [
-            FetchArchiveCall(
-                apollo: apollo,
-                space: space,
-                events: events,
-                initialDownloadState: initialDownloadState,
-                lastRefresh: lastRefresh
-            )
-        ]
+        lock.sync {
+            calls["fetchArchive"] = (calls["fetchArchive"] ?? []) + [
+                FetchArchiveCall(
+                    apollo: apollo,
+                    space: space,
+                    events: events,
+                    initialDownloadState: initialDownloadState,
+                    lastRefresh: lastRefresh
+                )
+            ]
+        }
 
         return impl(apollo, space, events, initialDownloadState)
     }