Implemented the FileServiceMock mock in the Tests target.

Tests/Library/Helpers/Mocks/FileServiceMock.swift

@@ -0,0 +1,84 @@
+import ColibriLibrary
+import Foundation
+
+struct FileServiceMock {
+    
+    // MARK: Properties
+    
+    private let action: Action?
+    private let folder: URL
+    
+    private weak var spy: FileServiceSpy?
+    
+    // MARK: Initialisers
+    
+    init(
+        currentFolder: URL,
+        action: Action? = nil,
+        spy: FileServiceSpy? = nil
+    ) {
+        self.action = action
+        self.folder = currentFolder
+        self.spy = spy
+    }
+    
+}
+
+// MARK: - FileServicing
+
+extension FileServiceMock: FileServicing {
+    
+    // MARK: Computed
+    
+    var currentFolder: URL {
+        get async { folder }
+    }
+    
+    // MARK: Functions
+    
+    func createFolder(at url: URL) async throws(FileServiceError) {
+        switch action {
+        case .error(let error):
+            throw error
+        case let .createFolder(url):
+            try await spy?.createFolder(at: url)
+        default:
+            break
+        }
+    }
+    
+    func delete(at url: URL) async throws(FileServiceError) {
+        switch action {
+        case .error(let error):
+            throw error
+        case let .delete(url):
+            try await spy?.delete(at: url)
+        default:
+            break
+        }
+    }
+    
+    func exists(at url: URL) async throws(FileServiceError) -> Bool {
+        switch action {
+        case .error(let error):
+            throw error
+        case let .exists(url, exists):
+            try await spy?.exists(at: url)
+            return exists
+        default:
+            return false
+        }
+    }
+    
+}
+
+// MARK: - Enumerations
+
+extension FileServiceMock {
+    enum Action {
+        case createFolder(URL)
+        case delete(URL)
+        case error(FileServiceError)
+        case exists(URL, Bool)
+    }
+}