net: return this from destroy()

PR-URL: #13530
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/net.md

@@ -643,6 +643,8 @@ callback.
 added: v0.1.90
 -->
 
+* Returns: {net.Socket}
+
 Ensures that no more I/O activity happens on this socket. Only necessary in
 case of errors (parse error or so).
 

doc/api/stream.md

@@ -515,8 +515,10 @@ A Writable stream in object mode will always ignore the `encoding` argument.
 added: v8.0.0
 -->
 
+* Returns: `this`
+
 Destroy the stream, and emit the passed error. After this call, the
-writible stream has ended. Implementors should not override this method,
+writable stream has ended. Implementors should not override this method,
 but instead implement [`writable._destroy`][writable-_destroy].
 
 ### Readable Streams

lib/internal/streams/destroy.js

@@ -14,7 +14,7 @@ function destroy(err, cb) {
                (!this._writableState || !this._writableState.errorEmitted)) {
       process.nextTick(emitErrorNT, this, err);
     }
-    return;
+    return this;
   }
 
   // we set destroyed to true before firing error callbacks in order
@@ -39,6 +39,8 @@ function destroy(err, cb) {
       cb(err);
     }
   });
+
+  return this;
 }
 
 function undestroy() {

test/parallel/test-net-socket-destroy-send.js

@@ -10,7 +10,8 @@ server.listen(0, common.mustCall(function() {
   const conn = net.createConnection(port);
 
   conn.on('connect', common.mustCall(function() {
-    conn.destroy();
+    // Test destroy returns this, even on multiple calls when it short-circuits.
+    assert.strictEqual(conn, conn.destroy().destroy());
     conn.on('error', common.mustCall(function(err) {
       assert.strictEqual(err.message, 'This socket is closed');
     }));