test: fix and improve error message

Add unexpected value to dgram socket type assertion and fix the size
entry.
PR-URL: #18449
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: kcaulfield94

test/parallel/test-dgram-createSocket-type.js

@@ -52,10 +52,12 @@ validTypes.forEach((validType) => {
 // note: linux will double the buffer size
 assert.ok(socket.getRecvBufferSize()===10000||
 socket.getRecvBufferSize()===20000,
-'SO_RCVBUF not 1300 or 2600');
+'SO_RCVBUF not 10000 or 20000, '+
+`was ${socket.getRecvBufferSize()}`);
 assert.ok(socket.getSendBufferSize()===15000||
 socket.getSendBufferSize()===30000,
-'SO_SNDBUF not 1800 or 3600');
+'SO_SNDBUF not 15000 or 30000, '+
+`was ${socket.getRecvBufferSize()}`);
 socket.close();
 }));
 }