Architecture: socket.end() doesn't disconnect until I write something

Am working on the port of Espruino to an ESP8266 and have found something I am not understanding. If I form a TCP socket connection to a partner and the invoke the "end()" method on the socket I am finding that the request to disconnect doesn't actually happen until after I try and transmit something further. For example:

var n = require("net");
var s = n.connect({
      host: "192.168.4.2",
      port: 25867
}, function(req) {
      print("Connected!: " + JSON.stringify(req));
      req.end();
});

doesn't cause the socket connection issued from the ESP8266 to be disconnected until I try the following:

var n = require("net");
var s = n.connect({
      host: "192.168.4.2",
      port: 25867
}, function(req) {
      print("Connected!: " + JSON.stringify(req));
      req.end();
      req.write("We should be already disconnected");
});

Unfortunately, I don't have a real Espruino board to test against so I can't tell if this is how it works on the real Espruino or whether I have broken something in the ESP8266 implementation.

How would I test this?

I'm happy to help, but I'm not sure how you test something like this.

@DrAzzy,
Many thanks for the offer .... and I WILL take you up on it. Starting Sunday morning, I have to put my toys away for 2 solid weeks while I attend to other stuff, but from the end of September, onwards I'll be back on the project at full strength. At that time, I'll post detailed instructions to test. I may also splurge and buy an Espruino board just for testing ....

Just to add, if you do a native Linux compile (even on a VM) this is dead easy to test, as you get a standard linux binary that you can run from the command-line and debug.

Thanks Gordon, I'll shoot for a Linux compile for testing. Did you have any thoughts on the content of the original question? Is this expected behavior that when we form a connect and then issue an end() that it doesn't actually end the TCP connection at that time?

Just checked on linux and it's as you say (but even doing end(" ") fixes it) - so yes, it's a bug. I'll see what I can do about fixing it.

Ok, if you pull from GitHub now it'll be fixed.

Awesome ... thanks Gordon .. I'll be testing now.

I'm hoping to make a big push this month to make some good progress. Hopefully this will involve some well tested "Pull requests" from my clone of the "espruino/Espruino" project. However, I'm still somewhat new to GitHub and want to make sure I don't make a mistake. Here is what I have done so far.

1. I went to Github: espruino/Espruino and executed a "Fork" which created nkolban/Espruino.
   
2. I made small changes to this fork and issued a "Pull request" which was accepted.
   
   

Now ... weeks have passed and I want to make sure that the "nkolban/Espruino" is still in synch with the "espruino/Espruino". Is there a mechanism/recipe/technique I should use to make sure that my fork is up-todate with "espruino/Espruino"?

GitHub has a doc on it here

Once you've set up github.com/espruino/Espruino as your upstream repository it's pretty basic to just pull any changes I make and merge them in.

Thank you sir ... that looks straight forward enough.