Replace occurrences of Error? for representing operation success/fail…

…ure with `Result<Void, Error>`
TrabelsiAchraf · Nov 25, 2021 · 72fb51d · 72fb51d
1 parent ef0a65a
commit 72fb51d
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Showing 9 changed files with 37 additions and 32 deletions.
diff --git a/EssentialFeed/Feed Cache/FeedStore.swift b/EssentialFeed/Feed Cache/FeedStore.swift
@@ -10,10 +10,10 @@ import Foundation
 public typealias CachedFeed = (feed: [LocalFeedImage], timestamp: Date)
 
 public protocol FeedStore {
-    typealias DeletionResult = Error?
+    typealias DeletionResult = Swift.Result<Void, Error>
     typealias DeletionCompletion = (DeletionResult) -> Void
 
-    typealias InsertionResult = Error?
+    typealias InsertionResult = Swift.Result<Void, Error>
     typealias InsertionCompletion = (InsertionResult) -> Void
 
     typealias RetrievalResult = Result<CachedFeed?, Error>

diff --git a/EssentialFeed/Feed Cache/Infrastructure/Codable/CodableFeedStore.swift b/EssentialFeed/Feed Cache/Infrastructure/Codable/CodableFeedStore.swift
@@ -68,9 +68,9 @@ public final class CodableFeedStore: FeedStore {
                 let cache = Cache(feed: feed.map(CodableFeedImage.init), timestamp: timestamp)
                 let encoded = try encoder.encode(cache)
                 try encoded.write(to: storeURL)
-                completion(nil)
+                completion(.success(()))
             } catch {
-                completion(error)
+                completion(.failure(error))
             }
         }
     }
@@ -79,14 +79,14 @@ public final class CodableFeedStore: FeedStore {
         let storeURL = self.storeURL
         queue.async(flags: .barrier) {
             guard FileManager.default.fileExists(atPath: storeURL.path) else {
-                return completion(nil)
+                return completion(.success(()))
             }
 
             do {
                 try FileManager.default.removeItem(at: storeURL)
-                completion(nil)
+                completion(.success(()))
             } catch {
-                completion(error)
+                completion(.failure(error))
             }
         }
     }

diff --git a/EssentialFeed/Feed Cache/Infrastructure/CoreData/CoreDataFeedStore.swift b/EssentialFeed/Feed Cache/Infrastructure/CoreData/CoreDataFeedStore.swift
@@ -38,9 +38,9 @@ public final class CoreDataFeedStore: FeedStore {
                 managedCache.feed = ManagedFeedImage.images(from: feed, in: context)
 
                 try context.save()
-                completion(nil)
+                completion(.success(()))
             } catch {
-                completion(error)
+                completion(.failure(error))
             }
         }
     }
@@ -49,9 +49,9 @@ public final class CoreDataFeedStore: FeedStore {
         perform { context in
             do {
                 try ManagedCache.find(in: context).map(context.delete).map(context.save)
-                completion(nil)
+                completion(.success(()))
             } catch {
-                completion(error)
+                completion(.failure(error))
             }
         }
     }

diff --git a/EssentialFeed/Feed Cache/LocalFeedLoader.swift b/EssentialFeed/Feed Cache/LocalFeedLoader.swift
@@ -18,24 +18,27 @@ public final class LocalFeedLoader {
 }
 
 extension LocalFeedLoader {
-    public typealias SaveResult = Error?
+    public typealias SaveResult = Result<Void, Error>
 
     public func save(_ feed: [FeedImage], completion: @escaping (SaveResult) -> Void) {
-        store.deleteCachedFeed { [weak self] error in
+        store.deleteCachedFeed { [weak self] deletionResult in
             guard let self = self else { return }
-
-            if let cachedDeletionError = error {
-                completion(cachedDeletionError)
-            } else {
+
+            switch deletionResult {
+            case .success:
                 self.cache(feed, with: completion)
+
+            case let .failure(error):
+                completion(.failure(error))
             }
         }
     }
 
     private func cache(_ feed: [FeedImage], with completion: @escaping (SaveResult) -> Void) {
-        store.insert(feed.toLocal(), timestamp: self.currentDate()) { [weak self] error in
+        store.insert(feed.toLocal(), timestamp: currentDate()) { [weak self] insertionResult in
             guard self != nil else { return }
-            completion(error)
+
+            completion(insertionResult)
         }
     }
 }

diff --git a/EssentialFeedAPIEndToEndTests/EssentialFeedAPIEndToEndTests.swift b/EssentialFeedAPIEndToEndTests/EssentialFeedAPIEndToEndTests.swift
@@ -48,7 +48,7 @@ class EssentialFeedAPIEndToEndTests: XCTestCase {
             exp.fulfill()
         }
 
-        wait(for: [exp], timeout: 15.0)
+        wait(for: [exp], timeout: 30.0)
 
         return receivedResult
     }

diff --git a/EssentialFeedCacheIntegrationTests/EssentialFeedCacheIntegrationTests.swift b/EssentialFeedCacheIntegrationTests/EssentialFeedCacheIntegrationTests.swift
@@ -65,8 +65,10 @@ class EssentialFeedCacheIntegrationTests: XCTestCase {
 
     private func save(_ feed: [FeedImage], with loader: LocalFeedLoader, file: StaticString = #file, line: UInt = #line) {
         let saveExp = expectation(description: "Wait for save completion")
-        loader.save(feed) { saveError in
-            XCTAssertNil(saveError, "Expected to save feed successfully", file: file, line: line)
+        loader.save(feed) { result in
+            if case let Result.failure(error) = result {
+                XCTAssertNil(error, "Expected to save feed successfully", file: file, line: line)
+            }
             saveExp.fulfill()
         }
         wait(for: [saveExp], timeout: 1.0)

diff --git a/EssentialFeedTests/Feed Cache/CacheFeedUseCaseTests.swift b/EssentialFeedTests/Feed Cache/CacheFeedUseCaseTests.swift
@@ -117,8 +117,8 @@ class CacheFeedUseCaseTests: XCTestCase {
         let exp = expectation(description: "Wait for save completion")
 
         var receivedError: Error?
-        sut.save(uniqueImageFeed().models) { error in
-            receivedError = error
+        sut.save(uniqueImageFeed().models) { result in
+            if case let Result.failure(error) = result { receivedError = error }
             exp.fulfill()
         }
 

diff --git a/EssentialFeedTests/Feed Cache/Helpers/FeedStoreSpy.swift b/EssentialFeedTests/Feed Cache/Helpers/FeedStoreSpy.swift
@@ -28,11 +28,11 @@ class FeedStoreSpy: FeedStore {
     }
 
     func completeDeletion(with error: Error, at index: Int = 0) {
-        deletionCompletions[index](error)
+        deletionCompletions[index](.failure(error))
     }
 
     func completeDeletionSuccessfully(at index: Int = 0) {
-        deletionCompletions[index](nil)
+        deletionCompletions[index](.success(()))
     }
 
     func insert(_ feed: [LocalFeedImage], timestamp: Date, completion: @escaping InsertionCompletion) {
@@ -41,11 +41,11 @@ class FeedStoreSpy: FeedStore {
     }
 
     func completeInsertion(with error: Error, at index: Int = 0) {
-        insertionCompletions[index](error)
+        insertionCompletions[index](.failure(error))
     }
 
     func completeInsertionSuccessfully(at index: Int = 0) {
-        insertionCompletions[index](nil)
+        insertionCompletions[index](.success(()))
     }
 
     func retrieve(completion: @escaping RetrievalCompletion) {

diff --git a/EssentialFeedTests/Feed Cache/XCTestCase+FeedStoreSpecs.swift b/EssentialFeedTests/Feed Cache/XCTestCase+FeedStoreSpecs.swift
@@ -120,8 +120,8 @@ extension FeedStoreSpecs where Self: XCTestCase {
     func insert(_ cache: (feed: [LocalFeedImage], timestamp: Date), to sut: FeedStore) -> Error? {
         let exp = expectation(description: "Wait for cache insertion")
         var insertionError: Error?
-        sut.insert(cache.feed, timestamp: cache.timestamp) { receivedInsertionError in
-            insertionError = receivedInsertionError
+        sut.insert(cache.feed, timestamp: cache.timestamp) { result in
+            if case let Result.failure(error) = result { insertionError = error }
             exp.fulfill()
         }
         wait(for: [exp], timeout: 1.0)
@@ -132,8 +132,8 @@ extension FeedStoreSpecs where Self: XCTestCase {
     func deleteCache(from sut: FeedStore) -> Error? {
         let exp = expectation(description: "Wait for cache deletion")
         var deletionError: Error?
-        sut.deleteCachedFeed { receivedDeletionError in
-            deletionError = receivedDeletionError
+        sut.deleteCachedFeed { result in
+            if case let Result.failure(error) = result { deletionError = error }
             exp.fulfill()
         }
         wait(for: [exp], timeout: 10.0)