Added immutable caching to the fingerprinted media types for the ConfigReader+Properties extension in the Website service target.

Services/Website/Tests/App/AppTests.swift

@@ -14,10 +14,14 @@ struct AppTests {
 
     // MARK: Constants
 
-    // Stylesheets and scripts are referenced through fingerprinted URLs, so they are served immutable.
+    // Referenced through fingerprinted URLs, or an immutable subset file in the case of a font, so all of these are served immutable.
     private let immutableExtensions: [AssetExtension] = [
         .css,
-        .js
+        .jpg,
+        .js,
+        .mp4,
+        .webp,
+        .woff2
     ]
 
     // Absolute path to the copy of the package's "Resources/Static" folder made into the test bundle

Services/Website/Tests/App/ConfigReaderPropertiesTests.swift

@@ -61,6 +61,44 @@ struct ConfigReaderPropertiesTests {
         #expect(reader(values: [.Analytics.websiteID: ""]).analytics == nil)
     }
 
+    @Test(arguments: [
+        "shared.css",
+        "shared.js",
+        "milker-400.woff2",
+        "booth.mp4",
+        "portrait.jpg",
+        "portrait.webp"
+    ])
+    func `cache control to mark the fingerprinted media immutable`(
+        file: String
+    ) throws {
+        let header = try #require(reader().cacheControl.getCacheControlHeader(for: file))
+
+        #expect(header.contains("immutable"))
+    }
+
+    @Test(arguments: [
+        // The icons are exempt: a browser fetches `/favicon.ico` unversioned whatever the markup says, and the manifest names the PNGs.
+        "favicon.ico",
+        "icon-192.png",
+        "icon.svg"
+    ])
+    func `cache control to leave the unversioned images mutable`(
+        file: String
+    ) throws {
+        let header = try #require(reader().cacheControl.getCacheControlHeader(for: file))
+
+        #expect(!header.contains("immutable"))
+    }
+
+    @Test
+    func `cache control to have the unversioned text revalidate`() throws {
+        let header = try #require(reader().cacheControl.getCacheControlHeader(for: "robots.txt"))
+
+        #expect(header.contains("must-revalidate"))
+        #expect(!header.contains("immutable"))
+    }
+
 }
 
 // MARK: - Helpers