socket.io with mocha test, The Should assert not throw error

Question

my test

For easy read, I delete some code.

I send a message hello to client1:

client1.emit('chat_to_user', {user: 'user2', message: 'hello'})

And client2 listen chat_to_user event.

it('chat', function(done) {
     client2.socket.on('chat_to_user', function(data) {
         data.message.should.equal('hello')
         done()
     });
});

this above test is fine, test passed.

change my test, it should throw error (but not)

But when I change client2 code:

it('chat', function(done) {
     client2.socket.on('chat_to_user', function(data) {
         //notice here!  the `data.message` should equal `hello`
         data.message.should.equal('i am fine')
         done()
     });
});

When I run test, It should throw an error, and tell me the error reason, like follow:

AssertionError: expected 'i am fine' to be 'hello'
      + expected - actual

      +"i am fine"
      -"hello"

But It didn't throw error reason, It just throw an timeout error:

Error: timeout of 5000ms exceeded

So, How to throw error reason with Socket.io test?

I am using socket.io 1.0

ryyppy · Answer 1 · 2014-12-05T13:03:46.287

Socket.io 1.0 handles errors by itself, so as soon as an error is raised, it will catch it and emit the error as an "error" event.

So as a complete test example, you can check the error object like this:

it('chat', function(done) {
    //Just to make clear what I understand as client2
    var client2 = io.connect(socketUrl, options);

    client2.socket.on('chat_to_user', function(data) {
        //notice here!  the `data.message` should equal `hello`
        data.message.should.equal('i am fine')
        done();
    });

    client2.on("error", function(err){
        done(new Error(err.description.message));
    });

    client1.emit('chat_to_user', {user: 'user2', message: 'hello'})
});

The throw statement throws the error back to mocha...

Sadly this is a lot of boiler-code, but it's a good place to start for a more clean solution!

Edit: To get a nice error message (expect messages etc.) you can involve the done callback like done(err) (updated example).

socket.io with mocha test, The Should assert not throw error

my test

change my test, it should throw error (but not)

1 Answers1