1 files changed, 50 insertions, 0 deletions
diff --git a/cli/tests/unit/serve_test.ts b/cli/tests/unit/serve_test.ts
index c6cfc45f3..0f97e17b8 100644
--- a/cli/tests/unit/serve_test.ts
+++ b/cli/tests/unit/serve_test.ts
@@ -15,6 +15,7 @@ import {
 
 const {
   upgradeHttpRaw,
+  addTrailers,
   // @ts-expect-error TypeScript (as of 3.7) does not support indexing namespaces by symbol
 } = Deno[Deno.internal];
 
@@ -2903,6 +2904,45 @@ Deno.test(
   },
 );
 
+// TODO(mmastrac): This test should eventually use fetch, when we support trailers there.
+// This test is ignored because it's flaky and relies on cURL's verbose output.
+Deno.test(
+  { permissions: { net: true, run: true, read: true }, ignore: true },
+  async function httpServerTrailers() {
+    const ac = new AbortController();
+    const listeningPromise = deferred();
+
+    const server = Deno.serve({
+      handler: () => {
+        const response = new Response("Hello World", {
+          headers: {
+            "trailer": "baz",
+            "transfer-encoding": "chunked",
+            "foo": "bar",
+          },
+        });
+        addTrailers(response, [["baz", "why"]]);
+        return response;
+      },
+      port: 4501,
+      signal: ac.signal,
+      onListen: onListen(listeningPromise),
+      onError: createOnErrorCb(ac),
+    });
+
+    // We don't have a great way to access this right now, so just fetch the trailers with cURL
+    const [_, stderr] = await curlRequestWithStdErr([
+      "http://localhost:4501/path",
+      "-v",
+      "--http2",
+      "--http2-prior-knowledge",
+    ]);
+    assertMatch(stderr, /baz: why/);
+    ac.abort();
+    await server;
+  },
+);
+
 Deno.test(
   { permissions: { net: true, run: true, read: true } },
   async function httpsServeCurlH2C() {
@@ -2948,3 +2988,13 @@ async function curlRequest(args: string[]) {
   assert(success);
   return new TextDecoder().decode(stdout);
 }
+
+async function curlRequestWithStdErr(args: string[]) {
+  const { success, stdout, stderr } = await new Deno.Command("curl", {
+    args,
+    stdout: "piped",
+    stderr: "piped",
+  }).output();
+  assert(success);
+  return [new TextDecoder().decode(stdout), new TextDecoder().decode(stderr)];
+}