Implemented the initialization functions for the DocCMiddleware type in the library target.

Tests/DocCMiddleware/Types/Extensions/Logger+Constants.swift

@@ -0,0 +1,29 @@
+// ===----------------------------------------------------------------------===
+//
+// This source file is part of the Hummingbird DocC Middleware open source project
+//
+// Copyright (c) 2025 Röck+Cöde VoF. and the Hummingbird DocC Middleware project authors
+// Licensed under the EUPL 1.2 or later.
+//
+// See LICENSE for license information
+// See CONTRIBUTORS for the list of Hummingbird DocC Middleware project authors
+//
+// ===----------------------------------------------------------------------===
+
+import Logging
+import Testing
+
+extension Logger {
+    
+    // MARK: Constants
+    
+    /// Creates a logger instance that is ready to use in test cases.
+    static let test: Self = {
+        var logger = Logger(label: "test.hummingbird-docc-middleware.logger")
+        
+        logger.logLevel = try! #require(Logger.Level.allCases.randomElement())
+        
+        return logger
+    }()
+    
+}

Tests/DocCMiddleware/Types/Extensions/Tag+Constants.swift

@@ -0,0 +1,22 @@
+// ===----------------------------------------------------------------------===
+//
+// This source file is part of the Hummingbird DocC Middleware open source project
+//
+// Copyright (c) 2025 Röck+Cöde VoF. and the Hummingbird DocC Middleware project authors
+// Licensed under the EUPL 1.2 or later.
+//
+// See LICENSE for license information
+// See CONTRIBUTORS for the list of Hummingbird DocC Middleware project authors
+//
+// ===----------------------------------------------------------------------===
+
+import Testing
+
+extension Tag {
+    
+    // MARK: Constants
+    
+    /// Tag that indicate a test case for a type initialization.
+    @Tag static var initializer: Self
+    
+}

Tests/DocCMiddleware/Types/Stubs/FileProviderStub.swift

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+// ===----------------------------------------------------------------------===
+//
+// This source file is part of the Hummingbird DocC Middleware open source project
+//
+// Copyright (c) 2025 Röck+Cöde VoF. and the Hummingbird DocC Middleware project authors
+// Licensed under the EUPL 1.2 or later.
+//
+// See LICENSE for license information
+// See CONTRIBUTORS for the list of Hummingbird DocC Middleware project authors
+//
+// ===----------------------------------------------------------------------===
+
+import Hummingbird
+
+/// A stub that conforms to the `FileProvider` protocol.
+struct FileProviderStub {}
+
+// MARK: - FileProvider
+
+extension FileProviderStub: FileProvider {
+    
+    // MARK: Type aliases
+    
+    typealias FileAttributes = String
+    typealias FileIdentifier = String
+    
+    // MARK: Functions
+    
+    func getFileIdentifier(_ path: String) -> String? {
+        nil
+    }
+    
+    func getAttributes(id: String) async throws -> String? {
+        nil
+    }
+    
+    func loadFile(
+        id: String,
+        context: some RequestContext
+    ) async throws -> ResponseBody {
+        .init()
+    }
+    
+    func loadFile(
+        id: String,
+        range: ClosedRange<Int>,
+        context: some RequestContext
+    ) async throws -> ResponseBody {
+        .init()
+    }
+    
+}
+