test(): implemented photo kit service tests

Author: Christian Elies

Sources/RemoteImage/private/Services/PhotoKitService.swift

@@ -9,22 +9,25 @@ protocol PhotoKitServiceProtocol {
                       _ completion: @escaping (Result<Data, Error>) -> Void)
 }
 
-final class PhotoKitService {}
+final class PhotoKitService {
+    static var asset: PHAsset.Type = PHAsset.self
+    static var imageManager: PHImageManager = PHImageManager.default()
+}
 
 extension PhotoKitService: PhotoKitServiceProtocol {
     func getPhotoData(localIdentifier: String,
                       _ completion: @escaping (Result<Data, Error>) -> Void) {
-        let fetchAssetsResult = PHAsset.fetchAssets(withLocalIdentifiers: [localIdentifier], options: nil)
+        let fetchAssetsResult = Self.asset.fetchAssets(withLocalIdentifiers: [localIdentifier], options: nil)
         guard let phAsset = fetchAssetsResult.firstObject else {
             completion(.failure(PhotoKitServiceError.phAssetNotFound(localIdentifier: localIdentifier)))
             return
         }
 
         let options = PHImageRequestOptions()
         options.isNetworkAccessAllowed = true
-        PHImageManager.default().requestImageDataAndOrientation(for: phAsset,
-                                                                options: options,
-                                                                resultHandler: { data, _, _, info in
+        Self.imageManager.requestImageDataAndOrientation(for: phAsset,
+                                                         options: options,
+                                                         resultHandler: { data, _, _, info in
             if let error = info?[PHImageErrorKey] as? Error {
                 completion(.failure(error))
             } else if let data = data {

Sources/RemoteImage/public/Models/PhotoKitServiceError.swift

@@ -5,6 +5,8 @@ public enum PhotoKitServiceError: Error {
     case phAssetNotFound(localIdentifier: String)
 }
 
+extension PhotoKitServiceError: Equatable {}
+
 extension PhotoKitServiceError: LocalizedError {
     public var errorDescription: String? {
         switch self {

Tests/RemoteImageTests/Mocks/MockImageManager.swift

@@ -0,0 +1,19 @@
+//
+//  MockImageManager.swift
+//  RemoteImageTests
+//
+//  Created by Christian Elies on 14.12.19.
+//
+
+import Photos
+
+final class MockImageManager: PHImageManager {
+    var imageRequestID = PHImageRequestID()
+    var dataToReturn: Data?
+    var infoToReturn: [AnyHashable:Any]?
+
+    override func requestImageDataAndOrientation(for asset: PHAsset, options: PHImageRequestOptions?, resultHandler: @escaping (Data?, String?, CGImagePropertyOrientation, [AnyHashable : Any]?) -> Void) -> PHImageRequestID {
+        resultHandler(dataToReturn, nil, .up, infoToReturn)
+        return imageRequestID
+    }
+}

Tests/RemoteImageTests/Mocks/MockPHAsset.swift

@@ -0,0 +1,16 @@
+//
+//  MockPHAsset.swift
+//  RemoteImageTests
+//
+//  Created by Christian Elies on 14.12.19.
+//
+
+import Photos
+
+final class MockPHAsset: PHAsset {
+    static var fetchResult = MockPHAssetFetchResult()
+
+    override class func fetchAssets(withLocalIdentifiers identifiers: [String], options: PHFetchOptions?) -> PHFetchResult<PHAsset> {
+        fetchResult
+    }
+}

Tests/RemoteImageTests/Mocks/MockPHAssetFetchResult.swift

@@ -0,0 +1,14 @@
+//
+//  MockPHAssetFetchResult.swift
+//  RemoteImageTests
+//
+//  Created by Christian Elies on 14.12.19.
+//
+
+import Photos
+
+final class MockPHAssetFetchResult: PHFetchResult<PHAsset> {
+    var firstObjectToReturn: PHAsset?
+
+    override var firstObject: PHAsset? { firstObjectToReturn }
+}

Tests/RemoteImageTests/Services/PhotoKitServiceTests.swift

@@ -0,0 +1,90 @@
+//
+//  PhotoKitServiceTests.swift
+//  RemoteImageTests
+//
+//  Created by Christian Elies on 15.12.19.
+//
+
+@testable import RemoteImage
+import Photos
+import XCTest
+
+final class PhotoKitServiceTests: XCTestCase {
+    let imageManager = MockImageManager()
+    let asset = MockPHAsset()
+    let service = PhotoKitService()
+    let localIdentifier = "TestIdentifier"
+
+    override func setUp() {
+        PhotoKitService.asset = MockPHAsset.self
+        PhotoKitService.imageManager = imageManager
+
+        MockPHAsset.fetchResult.firstObjectToReturn = nil
+        imageManager.dataToReturn = nil
+        imageManager.infoToReturn = nil
+    }
+
+    func testPhotoDataNotFound() {
+        let expectation = self.expectation(description: "PhotoDataResult")
+        var result: Result<Data, Error>?
+        service.getPhotoData(localIdentifier: localIdentifier) { res in
+            result = res
+            expectation.fulfill()
+        }
+
+        waitForExpectations(timeout: 2)
+
+        switch result {
+        case .failure(let error):
+            guard case PhotoKitServiceError.phAssetNotFound(localIdentifier) = error else {
+                XCTFail("Invalid error")
+                return
+            }
+        default:
+            XCTFail("Invalid photo data result")
+        }
+    }
+
+    func testPhotoDataFailure() {
+        MockPHAsset.fetchResult.firstObjectToReturn = asset
+        imageManager.infoToReturn = [PHImageErrorKey: PhotoKitServiceError.missingData]
+
+        let expectation = self.expectation(description: "PhotoDataResult")
+        var result: Result<Data, Error>?
+        service.getPhotoData(localIdentifier: localIdentifier) { res in
+            result = res
+            expectation.fulfill()
+        }
+
+        waitForExpectations(timeout: 2)
+
+        switch result {
+        case .failure(let error):
+            XCTAssertEqual(error as? PhotoKitServiceError, .missingData)
+        default:
+            XCTFail("Invalid photo data result")
+        }
+    }
+
+    func testPhotoDataSuccess() {
+        let expectedData = Data()
+        MockPHAsset.fetchResult.firstObjectToReturn = asset
+        imageManager.dataToReturn = expectedData
+
+        let expectation = self.expectation(description: "PhotoDataResult")
+        var result: Result<Data, Error>?
+        service.getPhotoData(localIdentifier: localIdentifier) { res in
+            result = res
+            expectation.fulfill()
+        }
+
+        waitForExpectations(timeout: 2)
+
+        switch result {
+        case .success(let data):
+            XCTAssertEqual(data, expectedData)
+        default:
+            XCTFail("Invalid photo data result")
+        }
+    }
+}