mocha watching fails under npm

[marcusoftnet]

Hi,

I have a very simple Koa application:

var app = module.exports = require("koa")();

app.use(function *(){
    this.body = "Koa says Hi!";
});

var port = process.env.PORT || (process.argv[2] || 3000);
port = (typeof port === "number") ? port : 3000;

app.listen(port);
console.log("Application started. Listening on port:" + port);

that I test with mocha and supertest like this;

var app = require("../");
var request = require("supertest").agent(app.listen());

describe("Our amazing site", function () {

    it("has a nice welcoming message", function (done) {
        request
            .get("/")
            .expect("Koa says Hi!")
            .end(done);
    });
});

I want to watch my files for changes and use the -w flag like this

mocha -u bdd -R min -w

That works fine. I change a file, the test is reexcuted and all is well.

Now I move that command into my package.json file as a script, like this:

"scripts": {
    "watch:test": "mocha -u bdd -R min -w"
  },

The first time I run the command it works, when I make a change that is picked up but now the test fails with:

1)  Uncaught error outside test suite:
     Uncaught Error: listen EADDRINUSE :::3000
      at Object.exports._errnoException (util.js:837:11)
      at exports._exceptionWithHostPort (util.js:860:20)
      at Server._listen2 (net.js:1231:14)
      at listen (net.js:1267:10)
      at Server.listen (net.js:1363:5)
      at Application.app.listen (node_modules/koa/lib/application.js:70:24)
      at Object.<anonymous> (index.js:10:5)
      at Object.<anonymous> (test/site.spec.js:1:73)
      at Array.forEach (native)
      at StatWatcher._handle.onchange (fs.js:1285:10)

That error will not go away until I stop mocha and then restart it.

Why does it behave differently when run via npm?
What can I do to fix this?

[dasilvacontin]

EADDRINUSE means that port is already in use. In you case, your server was not shutdown after the first test run. You should have a teardown hook (after) to shut down the server, stop listening to the port.

[marcusoftnet]

Aaah - that would do it. Night is falling here now. I'll check in on how to stop listening to a koa server tomorrow. Keep you posted

[marcusoftnet]

Ha - could of course not sleep after that. yes, your are correct. But I had to jump through some Koa-hoops to get there.

I now expose the server returned by app.listen() from the application and use that to close the server in my test.

Server:

var app = require("koa")();

app.use(function *(){
    this.body = "Koa says Hi!";
});

var port = process.env.PORT || (process.argv[2] || 3000);
port = (typeof port === "number") ? port : 3000;

var server = app.listen(port);
console.log("Application started. Listening on port:" + port);

module.exports = {
    server : server,
    app : app
};

Test:

var app = require("../").app;
var server = require("../").server;
var request = require("supertest").agent(server);

describe("Our amazing site", function () {

    after(function (done) {
        server.close();
        done();
    });

    it("has a nice welcoming message", function (done) {
        request
            .get("/")
            .expect("Koa says Hi!")
            .end(done);
    });
});

Thanks a bunch! Recording a screen cast for PluralSight and this stopped me in my tracks

[dasilvacontin]

No problemo!

And thanks much for posting back the solution! I tried finding the way to close the server to paste it back here and couldn't find it in less than 5min. I was left curious. :smile:

[marcusoftnet]

I wrote the whole thing down in a blog post, should anyone want to know more.

What I still fail to grasp is why this only failed when run as a script in npm. Running the same mocha command from the prompt worked fine

[allthesignals]

Why are error messages being suppressed? I can't figure out why I'm seeing this error. Is there any way to debug this? I tried the blog post, but maybe that API is out of date?

[igbominadeveloper]

This has saved me, I will spread the news!!!