Save automatically, improve mocks

CHDataManagement/Model/Page.swift

@@ -44,6 +44,8 @@ final class Page: Item, DateItem, LocalizedItem {
     @Published
     var requiredFiles: [FileResource]
 
+    var savedData: Data?
+
     init(content: Content,
          id: String,
          externalLink: String?,
@@ -186,7 +188,7 @@ final class Page: Item, DateItem, LocalizedItem {
 
 // MARK: Storage
 
-extension Page {
+extension Page: StorageItem {
 
     convenience init(context: LoadingContext, id: String, data: Data) {
         self.init(
@@ -202,10 +204,11 @@ extension Page {
             english: .init(context: context, data: data.english),
             tags: data.tags.compactMap(context.tag),
             requiredFiles: data.requiredFiles?.compactMap(context.file) ?? [])
+        savedData = data
     }
 
     /// The structure to store the metadata of a page on disk
-    struct Data: Codable {
+    struct Data: Codable, Equatable {
         let isDraft: Bool
         let externalLink: String?
         let tags: [String]
@@ -232,4 +235,8 @@ extension Page {
             english: english.data,
             requiredFiles: requiredFiles.nonEmpty?.map { $0.id }.sorted())
     }
+
+    func saveToDisk(_ data: Data) -> Bool {
+        content.storage.save(page: data, for: id)
+    }
 }