Improve mocking to avoid network calls in unit tests

Sources/LucaCore/Core/Downloader/Downloading.swift

@@ -2,6 +2,6 @@
 
 import Foundation
 
-protocol Downloading {
+public protocol Downloading {
     func downloadRelease(at url: URL) async throws -> URL
 }

Sources/LucaCore/Core/Installer/Installer.swift

@@ -20,22 +20,25 @@ public struct Installer {
     private let binaryFinder: BinaryFinding
     private let checksumValidator: ChecksumValidating
     private let architectureValidator: ArchitectureValidating
-    private let fileDownloader: FileDownloading
     private let downloader: Downloading
     private let permissionManager: PermissionManaging
     private let symLinker: SymLinking
     private let linkedToolsLister: LinkedToolsLister
     private let unlinker: Unlinker
     private let ignoreArchitectureCheck: Bool
 
-    public init(fileManager: FileManaging, ignoreArchitectureCheck: Bool, printer: Printing) {
+    public init(
+        fileManager: FileManaging,
+        ignoreArchitectureCheck: Bool,
+        printer: Printing,
+        downloader: Downloading? = nil
+    ) {
         self.fileManager = fileManager
         self.printer = printer
         self.binaryFinder = BinaryFinder(fileManager: fileManager)
         self.checksumValidator = ChecksumValidator(fileManager: fileManager)
         self.architectureValidator = ArchitectureValidator(fileManager: fileManager)
-        self.fileDownloader = FileDownloader(session: .shared)
-        self.downloader = Downloader(fileDownloader: fileDownloader)
+        self.downloader = downloader ?? Downloader(fileDownloader: FileDownloader(session: .shared))
         self.permissionManager = PermissionManager(fileManager: fileManager)
         self.symLinker = SymLinker(fileManager: fileManager)
         self.linkedToolsLister = LinkedToolsLister(fileManager: fileManager)

Tests/Fixtures/Lucafiles/Lucafile_mock.yml

@@ -0,0 +1,22 @@
+---
+tools:
+  - name: MockToolA
+    binaryPath: bin/ToggleGen
+    version: 1.0.0
+    url: https://example.com/mock/MockToolA.zip
+  - name: MockToolB
+    binaryPath: bin/ToggleGen
+    version: 2.0.0
+    url: https://example.com/mock/MockToolB.zip
+  - name: MockToolC
+    binaryPath: bin/ToggleGen
+    version: 3.0.0
+    url: https://example.com/mock/MockToolC.zip
+  - name: MockToolD
+    binaryPath: bin/ToggleGen
+    version: 4.0.0
+    url: https://example.com/mock/MockToolD.zip
+    checksum: 76b801daea0ed90f2871b0c66ebb8c4b9680d14e8011277d971cd74445fdaac5
+    algorithm: sha256
+
+version: 0.0.1

Tests/Fixtures/Lucafiles/Lucafile_mock_highversion.yml

@@ -0,0 +1,8 @@
+---
+tools:
+  - name: MockTool
+    binaryPath: bin/ToggleGen
+    version: 2.0.0
+    url: https://example.com/mock/MockTool-2.0.0.zip
+
+version: 0.0.1

Tests/Fixtures/Lucafiles/Lucafile_mock_lowversion.yml

@@ -0,0 +1,8 @@
+---
+tools:
+  - name: MockTool
+    binaryPath: bin/ToggleGen
+    version: 1.0.0
+    url: https://example.com/mock/MockTool-1.0.0.zip
+
+version: 0.0.1

Tests/Fixtures/Lucafiles/Lucafile_mock_subset.yml

@@ -0,0 +1,12 @@
+---
+tools:
+  - name: MockToolA
+    binaryPath: bin/ToggleGen
+    version: 1.0.0
+    url: https://example.com/mock/MockToolA.zip
+  - name: MockToolB
+    binaryPath: bin/ToggleGen
+    version: 2.0.0
+    url: https://example.com/mock/MockToolB.zip
+
+version: 0.0.1

Tests/Mocks/DownloaderMock.swift

@@ -0,0 +1,26 @@
+//  DownloaderMock.swift
+
+import Foundation
+import Testing
+@testable import LucaCore
+
+struct DownloaderMock: Downloading {
+
+    enum Result {
+        case fixture(Fixture)
+        case error(Error)
+    }
+
+    var result: Result
+
+    func downloadRelease(at url: URL) async throws -> URL {
+        switch result {
+        case .fixture(let fixture):
+            let bundle = Bundle.module
+            let path = try #require(bundle.path(forResource: fixture.filename, ofType: fixture.type))
+            return URL(fileURLWithPath: path)
+        case .error(let error):
+            throw error
+        }
+    }
+}