Test 404 under /snapshot (#4)

index.test.ts

@@ -24,7 +24,7 @@ for (const hostAddress of [
   "http://localhost:3000",
   "https://localhost:3001",
 ] as const) {
-  describe("/snapshot", () => {
+  describe(`${hostAddress.slice(0, hostAddress.indexOf("/") - 1)}: /snapshot`, () => {
     const snapshotFirstPathComp = "snapshot" as const;
     for (const [name, path] of [
       ["valid with a one-level subdir", "2025-01-02/a"],
@@ -53,5 +53,36 @@ for (const hostAddress of [
         );
       });
     }
+
+    for (const [name, path] of [
+      ["non-existing with no subdir", "non-existing"],
+      [
+        "non-existing with no subdir but with a trailing slash",
+        "non-existing/",
+      ],
+      ["non-existing with a one-level subdir", "non-existing/a"],
+      [
+        "non-existing with a one-level subdir with a trailing slash",
+        "non-existing/a/",
+      ],
+      ["non-existing with a two-level subdir", "non-existing/a/b"],
+      [
+        "non-existing with a two-level subdir with a trailing slash",
+        "non-existing/a/b/",
+      ],
+    ] as const) {
+      test(`Return 404 with invalid URL under /shapshot: ${name}`, async () => {
+        const response = await fetch(
+          `${hostAddress}/${snapshotFirstPathComp}/${path}`,
+          {
+            redirect: "manual",
+          },
+        );
+
+        expect(response.status).toBe(404);
+        expect(response.headers.get("content-type")).toContain("text/plain");
+        expect(await response.text()).toBe("404 Not Found");
+      });
+    }
   });
 }