test: http2Stream redundant shutdown and single cb

PR-URL: https://github.com/nodejs/node/pull/15612
Refs: https://github.com/nodejs/node/issues/14985
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

test/parallel/test-http2-server-shutdown-redundant.js

@@ -0,0 +1,29 @@
+'use strict';
+
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+const assert = require('assert');
+const http2 = require('http2');
+
+const server = http2.createServer();
+
+// Test blank return when a stream.session.shutdown is called twice
+// Also tests stream.session.shutdown with just a callback function (no options)
+server.on('stream', common.mustCall((stream) => {
+  stream.session.shutdown(common.mustCall(() => {
+    assert.strictEqual(
+      stream.session.shutdown(common.mustNotCall()),
+      undefined
+    );
+  }));
+  stream.session.shutdown(common.mustNotCall());
+}));
+
+server.listen(0, common.mustCall(() => {
+  const client = http2.connect(`http://localhost:${server.address().port}`);
+
+  const req = client.request();
+  req.resume();
+  req.on('end', common.mustCall(() => server.close()));
+}));