Implemented the Resource model in the library target.

Sources/HummingbirdDocC/Internal/Extensions/String+Formats.swift

@@ -31,6 +31,8 @@ extension String {
             static let forwardSlash = "%@/"
             /// A format pattern used to generate relative paths for index files.
             static let index = "%@/%@/index.html"
+            /// A format pattern used to generate relative paths for resources.
+            static let resource = "/%@/%@"
             /// A format pattern used to generate relative paths that starts with the `/` string.
             static let root = "/%@"
         }

Sources/HummingbirdDocC/Internal/Models/Resource.swift

@@ -0,0 +1,55 @@
+// ===----------------------------------------------------------------------===
+//
+// 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
+//
+// ===----------------------------------------------------------------------===
+
+/// A model that encapsulates the information related to a resource in a given `DocC` documentation archive.
+struct Resource {
+    
+    // MARK: Properties
+    
+    /// An archive name in which the resource belongs to.
+    let archiveName: String
+    
+    /// A relative URI path to the resource.
+    let relativePath: String
+    
+    // MARK: Initializers
+    
+    /// Initializes this resource.
+    /// - Parameters:
+    ///   - archiveName: An archive name in which the resource belongs to.
+    ///   - relativePath: A relative URI path to the resource.
+    init(
+        archiveName: String,
+        relativePath: String
+    ) {
+        self.archiveName = archiveName
+        self.relativePath = relativePath
+    }
+    
+    // MARK: Computed
+    
+    /// A relative URI path to a documentation archive the resource belongs to.
+    lazy var archivePath: String = {
+        .init(format: .Format.Path.archive, archiveName)
+    }()
+    
+    /// A reference name for the documentation archive the resource belongs to.
+    lazy var archiveReference: String = {
+        archiveName.lowercased()
+    }()
+    
+    /// A relative URI path to the resource in its documentation archive.
+    lazy var fullPath: String = {
+        .init(format: .Format.Path.archive, archiveName, relativePath)
+    }()
+    
+}

Tests/HummingbirdDocC/Tests/Internal/Models/ResourceTests.swift

@@ -0,0 +1,147 @@
+// ===----------------------------------------------------------------------===
+//
+// 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
+
+@testable import HummingbirdDocC.Resource
+
+@Suite("Resource", .tags(.model))
+struct ResourceTests {
+    
+    // MARK: Properties tests
+    
+#if swift(>=6.2)
+    @Test
+    func `archive path`() {
+        assertArchivePath(
+            archiveName: "SomeDocument",
+            expects: "/SomeDocument.doccarchive"
+        )
+    }
+    
+    @Test
+    func `archive reference`() {
+        assertArchiveReference(
+            archiveName: "SomeDocument",
+            expects: "somedocument"
+        )
+    }
+    
+    @Test
+    func `full path`() {
+        assertFullPath()(
+            archiveName: "SomeDocument",
+            relativePath: .uriResource,
+            expects: "/somedocument" + .uriResource
+        )
+    }
+#else
+    @Test("archive path")
+    func archivePath() {
+        assertArchivePath(
+            archiveName: "SomeDocument",
+            expects: "/SomeDocument.doccarchive"
+        )
+    }
+    
+    @Test("archive reference")
+    func archiveReference() {
+        assertArchiveReference(
+            archiveName: "SomeDocument",
+            expects: "somedocument"
+        )
+    }
+    
+    @Test("full path")
+    func fullPath() {
+        assertFullPath()(
+            archiveName: "SomeDocument",
+            relativePath: .uriResource,
+            expects: "/somedocument" + .uriResource
+        )
+    }
+#endif
+    
+}
+
+// MARK: - Assertions
+
+private extension ResourceTests {
+    
+    // MARK: Functions
+    
+    /// Asserts the `archivePath` computed property of a resource.
+    /// - Parameters:
+    ///   - archiveName: A name of the archive the resource belongs to.
+    ///   - archivePath: An expected path to a documentation archive related to a given archive name.
+    func assertArchivePath(
+        archiveName: String,
+        expects archivePath: String
+    ) {
+        // GIVEN
+        let resource = Resource(
+            archiveName: archiveName,
+            relativePath: .empty
+        )
+
+        // WHEN
+        let result = resource.archivePath
+
+        // THEN
+        #expect(result == archivePath)
+    }
+
+    /// Asserts the `archiveReference` computed property of a resource.
+    /// - Parameters:
+    ///   - archiveName: A name of the archive the resource belongs to.
+    ///   - archiveReference: An expected reference related to a given archive name.
+    func assertArchiveReference(
+        archiveName: String,
+        expects archiveReference: String
+    ) {
+        // GIVEN
+        let resource = Resource(
+            archiveName: archiveName,
+            relativePath: .empty
+        )
+        
+        // WHEN
+        let result = resource.archiveReference
+        
+        // THEN
+        #expect(result == archiveReference)
+    }
+
+    /// Asserts the `fullPath` computed property of a resource.
+    /// - Parameters:
+    ///   - archiveName: A name of the archive the resource belongs to.
+    ///   - relativePath: A relative URI path to a resource.
+    ///   - fullPath: An expected relative URI path to a resource in its documentation archive.
+    func assertFullPath(
+        archiveName: String,
+        relativePath: String,
+        expects fullPath: String
+    ) {
+        // GIVEN
+        let resource = Resource(
+            archiveName: archiveName,
+            relativePath: relativePath
+        )
+
+        // WHEN
+        let result = resource.fullPath
+        
+        // THEN
+        #expect(result == fullPath)
+    }
+    
+}

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

@@ -22,6 +22,8 @@ extension Tag {
     @Tag static var `extension`: Self
     /// Tag that indicate a test case for a middleware type.
     @Tag static var middleware: Self
+    /// Tag that indicate a test case for a model type.
+    @Tag static var model: Self
     /// Tag that indicate a test case for a use case type.
     @Tag static var useCase: Self