diff --git a/test_plugin/README.md b/test_plugin/README.md
new file mode 100644
index 0000000000..b340389ce4
--- /dev/null
+++ b/test_plugin/README.md
@@ -0,0 +1,9 @@
+# `test_plugin` crate
+
+## To run this test manually
+
+```
+cd test_plugin
+
+../target/debug/deno run --unstable --allow-plugin tests/test.js debug
+```
diff --git a/test_plugin/tests/integration_tests.rs b/test_plugin/tests/integration_tests.rs
index 724af3d70f..57499a31bb 100644
--- a/test_plugin/tests/integration_tests.rs
+++ b/test_plugin/tests/integration_tests.rs
@@ -1,7 +1,4 @@
 // Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
-// To run this test manually:
-//   cd test_plugin
-//   ../target/debug/deno run --unstable --allow-plugin tests/test.js debug
 
 use std::process::Command;
 use test_util::deno_cmd;
@@ -37,7 +34,7 @@ fn basic() {
     println!("stderr {}", stderr);
   }
   assert!(output.status.success());
-  let expected = "Hello from plugin.\nzero_copy[0]: test\nzero_copy[1]: 123\nzero_copy[2]: cba\nPlugin Sync Response: test\nHello from plugin.\nzero_copy[0]: test\nzero_copy[1]: 123\nPlugin Async Response: test\n";
+  let expected = "Hello from plugin.\nzero_copy[0]: test\nzero_copy[1]: 123\nzero_copy[2]: cba\nPlugin Sync Response: test\nHello from plugin.\nzero_copy[0]: test\nzero_copy[1]: 123\nzero_copy[2]: cba\nPlugin Async Response: test\n";
   assert_eq!(stdout, expected);
   assert_eq!(stderr, "");
 }
diff --git a/test_plugin/tests/test.js b/test_plugin/tests/test.js
index f195c09282..90e6b43cad 100644
--- a/test_plugin/tests/test.js
+++ b/test_plugin/tests/test.js
@@ -53,6 +53,7 @@ function runTestAsync() {
     testAsync,
     new Uint8Array([116, 101, 115, 116]),
     new Uint8Array([49, 50, 51]),
+    new Uint8Array([99, 98, 97]),
   );
 
   if (response != null || response != undefined) {