fix(fileserver): wrong url href of displayed files (denoland/deno_std#426)

Original: https://github.com/denoland/deno_std/commit/be6cd35cbf65ef49b15bf0faf1e582d79f5a0f87

http/file_server.ts

@@ -162,7 +162,7 @@ async function serveDir(
     listEntry.push(
       createDirEntryDisplay(
         info.name,
-        fn,
+        fn.replace(currentDir, ""),
         info.isFile() ? info.len : null,
         mode,
         info.isDirectory()

http/file_server_test.ts

@@ -56,6 +56,18 @@ test(async function serveDirectory(): Promise<void> {
     assert(res.headers.has("access-control-allow-headers"));
     const page = await res.text();
     assert(page.includes("azure-pipelines.yml"));
+
+    // `Deno.FileInfo` is not completely compatible with Windows yet
+    // TODO: `mode` should work correctly in the future. Correct this test case accordingly.
+    Deno.platform.os !== "win" &&
+      assert(/<td class="mode">\([a-zA-Z-]{10}\)<\/td>/.test(page));
+    Deno.platform.os === "win" &&
+      assert(/<td class="mode">\(unknown mode\)<\/td>/.test(page));
+    assert(
+      page.includes(
+        `<td><a href="/azure-pipelines.yml">azure-pipelines.yml</a></td>`
+      )
+    );
   } finally {
     killFileServer();
   }