From 7d0ad3461ad117f92c260c50fc96c56e6ad90576 Mon Sep 17 00:00:00 2001
From: Javier Cicchelli <javier@rock-n-code.com>
Date: Sat, 11 Jan 2025 03:24:22 +0100
Subject: [PATCH] Implemented the "exists(at: )" function for the FileService
 service in the module target.

---
 Sources/Library/Protocols/FileServicing.swift | 18 +++++-
 Sources/Library/Services/FileService.swift    | 38 ++++++++++---
 Tests/Library/Services/FileServiceTests.swift | 57 +++++++++++++++++--
 3 files changed, 98 insertions(+), 15 deletions(-)

diff --git a/Sources/Library/Protocols/FileServicing.swift b/Sources/Library/Protocols/FileServicing.swift
index 55dc203..cff10db 100644
--- a/Sources/Library/Protocols/FileServicing.swift
+++ b/Sources/Library/Protocols/FileServicing.swift
@@ -1,9 +1,23 @@
 import Foundation
 
-protocol FileServicing {
+public protocol FileServicing {
     
-    // MARK: Properties
+    // MARK: Computed
     
     var currentFolder: URL { get async }
     
+    // MARK: Functions
+    
+    func exists(at url: URL) async throws (FileServiceError) -> Bool
+    
+}
+
+// MARK: - Errors
+
+public enum FileServiceError: Error, Equatable {
+    case folderNotCreated
+    case folderNotDeleted
+    case urlAlreadyExists
+    case urlNotExists
+    case urlNotFileURL
 }
diff --git a/Sources/Library/Services/FileService.swift b/Sources/Library/Services/FileService.swift
index a81b2ce..4c164e7 100644
--- a/Sources/Library/Services/FileService.swift
+++ b/Sources/Library/Services/FileService.swift
@@ -1,6 +1,6 @@
 import Foundation
 
-struct FileService: FileServicing {
+public struct FileService: FileServicing {
 
     // MARK: Properties
     
@@ -8,19 +8,41 @@ struct FileService: FileServicing {
     
     // MARK: Initialisers
     
-    init(fileManager: FileManager = .default) {
+    public init(fileManager: FileManager = .default) {
         self.fileManager = fileManager
     }
     
     // MARK: Computed
     
-    var currentFolder: URL {
+    public var currentFolder: URL {
         get async {
-            if #available(macOS 13.0, *) {
-                .init(filePath: fileManager.currentDirectoryPath)
-            } else {
-                .init(fileURLWithPath: fileManager.currentDirectoryPath)
-            }
+            .init(at: fileManager.currentDirectoryPath)
+        }
+    }
+    
+    public func exists(at url: URL) async throws (FileServiceError) -> Bool {
+        guard url.isFileURL else {
+            throw FileServiceError.urlNotFileURL
+        }
+        
+        let filePath = getPath(for: url)
+        
+        return fileManager.fileExists(atPath: filePath)
+    }
+    
+}
+
+// MARK: - Helpers
+
+private extension FileService {
+    
+    // MARK: Functions
+    
+    func getPath(for url: URL) -> String {
+        if #available(macOS 13.0, *) {
+            return url.path()
+        } else {
+            return url.path
         }
     }
     
diff --git a/Tests/Library/Services/FileServiceTests.swift b/Tests/Library/Services/FileServiceTests.swift
index 01878a2..7dde431 100644
--- a/Tests/Library/Services/FileServiceTests.swift
+++ b/Tests/Library/Services/FileServiceTests.swift
@@ -1,22 +1,69 @@
+import Foundation
 import Testing
 
 @testable import ColibriLibrary
 
 struct FileServiceTests {
+    
+    // MARK: Properties
+    
+    private let service: FileServicing
+    
+    // MARK: Initialisers
+    
+    init() {
+        self.service = FileService()
+    }
 
     // MARK: Properties tests
 
-    @Test("Test the file service provides a current folder URL")
-    func currentFolder() async {
+    @Test func currentFolder() async {
         // GIVEN
-        let service = FileService()
-
         // WHEN
         let url = await service.currentFolder
 
         // THEN
-        #expect(url.path() == "/private/tmp")
+        #expect(url == .someExistingFolder)
         #expect(url.isFileURL == true)
     }
+        // GIVEN
+        // WHEN
+        // THEN
+    }
+    
+    @Test(arguments: zip([URL.someExistingFolder, .someExistingFile, .someNonExistingFolder, .someNonExistingFile],
+                         [true, true, false, false]))
+    func exists(
+        with url: URL,
+        expects outcome: Bool
+    ) async throws {
+        // GIVEN
+        // WHEN
+        let result = try await service.exists(at: url)
+        
+        // THEN
+        #expect(result == outcome)
+    }
+    
+    @Test func existsThrows() async throws {
+        // GIVEN
+        let url = URL.someRandomURL
+
+        // WHEN
+        // THEN
+        await #expect(throws: FileServiceError.urlNotFileURL) {
+            try await service.exists(at: url)
+        }
+    }
 
 }
+
+// MARK: - URL+Constants
+
+private extension URL {
+    static let someExistingFolder = URL(at: "/private/tmp")
+    static let someExistingFile = URL(at: "/etc/null")
+    static let someNonExistingFolder = URL(at: "/some/random/folder")
+    static let someNonExistingFile = URL(at: "/some/random/file.ext")
+    static let someRandomURL = URL(string: "https://some.random.url")!
+}