Save automatically, improve mocks

CHDataManagement/Storage/StorageItem.swift

@@ -0,0 +1,38 @@
+
+protocol StorageItem: AnyObject {
+
+    associatedtype Data: Equatable
+
+    var savedData: Data? { get set }
+
+    var data: Data { get }
+
+    func saveToDisk(_ data: Data) -> Bool
+}
+
+extension StorageItem {
+
+    /**
+     Get the data to save, if the object has changed
+     */
+    func dataToSave() -> Data? {
+        guard let savedData else {
+            return data
+        }
+        if savedData != data {
+            return data
+        }
+        return nil
+    }
+
+    func saveIfNeeded() -> Bool? {
+        guard let data = dataToSave() else {
+            return nil
+        }
+        guard saveToDisk(data) else {
+            return false
+        }
+        savedData = data
+        return true
+    }
+}