Defined the AppArguments protocol in the sample target and also, conformed the SampleAppArguments type to it.

Samples/DocCMiddleware/Parameters/SampleAppArguments.swift

@@ -13,25 +13,31 @@
 import protocol ArgumentParser.ParsableArguments
 
 import struct ArgumentParser.Option
+import struct Logging.Logger
 
 extension SampleApp {
-    /// A type that conforms to the `ParsableArguments` protocol, which contains the input parameters required for the execution of the sample executable.
-    struct Parameters: ParsableArguments {
+    /// A type that conforms to the ``AppArguments`` and the `ParsableArguments` protocols, which contains the input parameters required for the
+    /// execution of the sample executable.
+    struct Arguments: AppArguments, ParsableArguments {
         
         // MARK: Properties
 
-        /// A label given to the sample app to identify it within a communications channel.
         @Option(
             name: .shortAndLong,
             help: "A label given to the sample app for the sole purpose of identification within a communications channel."
         )
         var hostname: String = "127.0.0.1"
     
-        /// A port number assigned to the sample app from where the app either sends or receives data.
         @Option(
             name: .shortAndLong,
             help: "A port number assigned to the sample app from where the app either sends or receives data."
         )
         var port: Int = 8080
+        
+        @Option(
+            name: .long,
+            help: "A log level to configure in a type that interacts with the logging system."
+        )
+        var logLevel: Logger.Level?
     }
 }

Samples/DocCMiddleware/Protocols/AppArguments.swift

@@ -0,0 +1,40 @@
+// ===----------------------------------------------------------------------===
+//
+// 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 protocol ArgumentParser.ExpressibleByArgument
+
+import struct Logging.Logger
+
+/// A protocol that defines the input arguments the sample executable requires to run.
+protocol AppArguments {
+    
+    // MARK: Properties
+    
+    /// A label given to the sample app to identify it within a communications channel.
+    var hostname: String { get }
+    
+    /// A port number assigned to the sample app from where the app either sends or receives data.
+    var port: Int { get }
+    
+    /// A log level to configure in a type that interacts with the logging system.
+    var logLevel: Logger.Level? { get }
+    
+}
+
+// MARK: - Conformances
+
+/// Extends the `Logger.Level` type so it can be used as an argument.
+#if hasFeature(RetroactiveAttribute)
+extension Logger.Level: @retroactive ExpressibleByArgument {}
+#else
+extension Logger.Level: ExpressibleByArgument {}
+#endif

Samples/DocCMiddleware/SampleApp.swift

@@ -18,7 +18,7 @@ import struct ArgumentParser.OptionGroup
     // MARK: Properties
     
     /// A type that contains all the necessary input parameters to run the sample executable.
-    @OptionGroup var parameters: Parameters
+    @OptionGroup var arguments: Arguments
 
 }
 

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

@@ -53,5 +53,5 @@ extension Logger {
 
 private extension String {
     /// A label to assign to a test logger instance.
-    static let loggerLabel = "test.hummingbird-docc-middleware.logger"
+    static let loggerLabel = "test.hummingbird-docc.logger"
 }