DataReceivingSideEffect protocol and (failing) tests

Kingfisher.xcodeproj/project.pbxproj

@@ -41,6 +41,7 @@
 		4B8E291D216F40AA0095FAD1 /* AuthenticationChallengeResponsable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B8E291B216F40AA0095FAD1 /* AuthenticationChallengeResponsable.swift */; };
 		4B8E291E216F40AA0095FAD1 /* AuthenticationChallengeResponsable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B8E291B216F40AA0095FAD1 /* AuthenticationChallengeResponsable.swift */; };
 		4B8E291F216F40AA0095FAD1 /* AuthenticationChallengeResponsable.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4B8E291B216F40AA0095FAD1 /* AuthenticationChallengeResponsable.swift */; };
+		4BA3BF1E228BCDD100909201 /* DataReceivingSideEffectTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BA3BF1D228BCDD100909201 /* DataReceivingSideEffectTests.swift */; };
 		4BCFF7A621990DB70055AAC4 /* MemoryStorageTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BCFF7A521990DB60055AAC4 /* MemoryStorageTests.swift */; };
 		4BCFF7A721990DB70055AAC4 /* MemoryStorageTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BCFF7A521990DB60055AAC4 /* MemoryStorageTests.swift */; };
 		4BCFF7A821990DB70055AAC4 /* MemoryStorageTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4BCFF7A521990DB60055AAC4 /* MemoryStorageTests.swift */; };
@@ -295,6 +296,7 @@
 		4B8351CB217084660081EED8 /* Runtime.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Runtime.swift; sourceTree = "<group>"; };
 		4B8E2916216F3F7F0095FAD1 /* ImageDownloaderDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ImageDownloaderDelegate.swift; sourceTree = "<group>"; };
 		4B8E291B216F40AA0095FAD1 /* AuthenticationChallengeResponsable.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AuthenticationChallengeResponsable.swift; sourceTree = "<group>"; };
+		4BA3BF1D228BCDD100909201 /* DataReceivingSideEffectTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DataReceivingSideEffectTests.swift; sourceTree = "<group>"; };
 		4BCCF3441D5B0457003387C2 /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		4BCFF7A521990DB60055AAC4 /* MemoryStorageTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MemoryStorageTests.swift; sourceTree = "<group>"; };
 		4BCFF7A9219932390055AAC4 /* DiskStorageTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DiskStorageTests.swift; sourceTree = "<group>"; };
@@ -608,6 +610,7 @@
 				D1E564402199C21E0057AAE3 /* StorageExpirationTests.swift */,
 				D1A1CC9E21A0F98600263AD8 /* ImageDataProviderTests.swift */,
 				D1BFED94222ACC6B009330C8 /* ImageProcessorTests.swift */,
+				4BA3BF1D228BCDD100909201 /* DataReceivingSideEffectTests.swift */,
 			);
 			name = KingfisherTests;
 			path = Tests/KingfisherTests;
@@ -885,6 +888,7 @@
 			developmentRegion = en;
 			hasScannedForEncodings = 0;
 			knownRegions = (
+				en,
 				Base,
 			);
 			mainGroup = D1ED2D021AD2CFA600CFC3EB;
@@ -1338,6 +1342,7 @@
 				D1DC4B411D60996D00DFDFAA /* StringExtensionTests.swift in Sources */,
 				D1BFED95222ACC6B009330C8 /* ImageProcessorTests.swift in Sources */,
 				D12E0C501C47F23500AC98AD /* ImageCacheTests.swift in Sources */,
+				4BA3BF1E228BCDD100909201 /* DataReceivingSideEffectTests.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

Sources/General/KingfisherOptionsInfo.swift

@@ -216,6 +216,13 @@ public enum KingfisherOptionsInfoItem {
     
     /// Enable progressive image loading, Kingfisher will use the `ImageProgressive` of
     case progressiveJPEG(ImageProgressive)
+
+    case onDataReceived([DataReceivingSideEffect])
+}
+
+
+public protocol DataReceivingSideEffect {
+    func onDataReceived(_ latest: Data, allData: Data)
 }
 
 // Improve performance by parsing the input `KingfisherOptionsInfo` (self) first.
@@ -254,7 +261,9 @@ public struct KingfisherParsedOptionsInfo {
     public var memoryCacheExpiration: StorageExpiration? = nil
     public var diskCacheExpiration: StorageExpiration? = nil
     public var processingQueue: CallbackQueue? = nil
-    public var progressiveJPEG: ImageProgressive?
+    public var progressiveJPEG: ImageProgressive? = nil
+
+    public var onDataReceived: [DataReceivingSideEffect]? = nil
     
     public init(_ info: KingfisherOptionsInfo?) {
         guard let info = info else { return }
@@ -291,6 +300,7 @@ public struct KingfisherParsedOptionsInfo {
             case .diskCacheExpiration(let expiration): diskCacheExpiration = expiration
             case .processingQueue(let queue): processingQueue = queue
             case .progressiveJPEG(let value): progressiveJPEG = value
+            case .onDataReceived(let value): onDataReceived = value
             }
         }
 

Tests/KingfisherTests/DataReceivingSideEffectTests.swift

@@ -25,6 +25,7 @@
 //  THE SOFTWARE.
 
 import XCTest
+@testable import Kingfisher
 
 class DataReceivingSideEffectTests: XCTestCase {
 
@@ -36,9 +37,20 @@ class DataReceivingSideEffectTests: XCTestCase {
         // Put teardown code here. This method is called after the invocation of each test method in the class.
     }
 
-    func testExample() {
-        // This is an example of a functional test case.
-        // Use XCTAssert and related functions to verify your tests produce the correct results.
+    func testDataReceivingSideEffectBlockCanBeCalled() {
+        let exp = expectation(description: #function)
+        let url = testURLs[0]
+        stub(url, data: testImageData)
+
+        let receiver = DataReceivingStub()
+
+        let options: KingfisherOptionsInfo = [.onDataReceived([receiver])]
+        KingfisherManager.shared.retrieveImage(with: url, options: options) {
+            result in
+            XCTAssertTrue(receiver.called)
+            exp.fulfill()
+        }
+        waitForExpectations(timeout: 3, handler: nil)
     }
 
     func testPerformanceExample() {
@@ -49,3 +61,10 @@ class DataReceivingSideEffectTests: XCTestCase {
     }
 
 }
+
+class DataReceivingStub: DataReceivingSideEffect {
+    var called: Bool = false
+    func onDataReceived(_ latest: Data, allData: Data) {
+        called = true
+    }
+}