Running express server in hooks.beforeAll never enters callback function (hangs)

[justin-calleja]

I'm trying to start an express server before running dredd in hooks.beforeAll but execution is never entering express server's onListening callback. It just hangs indefinitely.

npm run dredd

dredd npm script is: dredd ./api.apib http://localhost:9311 --hookfiles=./*-hooks.js

What is in your dredd.yml?

Not using a dredd.yml in this bare bones test.

What's your dredd --version output?

$ ./node_modules/.bin/dredd --version
dredd v2.2.5 (Darwin 15.4.0; x64)

Does dredd --level=debug uncover something?

No:

> dredd ./api.apib http://localhost:9311 --hookfiles=./*-hooks.js --level=debug

verbose: Loading configuration file: ./dredd.yml
debug: Dredd version: 2.2.5
debug: Node.js version: v6.3.1
debug: Node.js environment: http_parser=2.7.0, node=6.3.1, v8=5.0.71.57, uv=1.9.1, zlib=1.2.8, ares=1.10.1-DEV, icu=57.1, modules=48, openssl=1.0.2h
debug: System version: Darwin 15.4.0 x64
debug: npm version: 3.10.3
debug: Configuration: {"server":"http://localhost:9311","options":{"_":["./api.apib"],"hookfiles":"./*-hooks.js","f":"./*-hooks.js","level":"debug","l":"debug","dry-run":null,"y":null,"language":"nodejs","a":"nodejs","sandbox":false,"b":false,"server":null,"g":null,"server-wait":3,"init":false,"i":false,"custom":{},"j":[],"names":false,"n":false,"only":[],"x":[],"reporter":[],"r":[],"output":[],"o":[],"header":[],"h":[],"sorted":false,"s":false,"user":null,"u":null,"inline-errors":false,"e":false,"details":false,"d":false,"method":[],"m":[],"color":true,"c":true,"timestamp":false,"t":false,"silent":false,"q":false,"path":["./api.apib","./api.apib"],"p":["./api.apib","./api.apib"],"hooks-worker-timeout":5000,"hooks-worker-connect-timeout":1500,"hooks-worker-connect-retry":500,"hooks-worker-after-connect-wait":100,"hooks-worker-term-timeout":5000,"hooks-worker-term-retry":500,"hooks-worker-handler-host":"localhost","hooks-worker-handler-port":61321,"config":"./dredd.yml","$0":"/Users/justin/tmp/tmp-dredd2/dredd-and-express/node_modules/.bin/dredd"},"custom":{"cwd":"/Users/justin/tmp/tmp-dredd2/dredd-and-express","argv":["./api.apib","http://localhost:9311","--hookfiles=./*-hooks.js","--level=debug"]}}
verbose: Using 'base' reporter.
verbose: Configuring reporters: []
verbose: Using 'cli' reporter.
verbose: No backend server process specified, starting testing at once.
verbose: Running Dredd instance.
verbose: Expanding glob patterns.
verbose: Reading API description files.
verbose: Parsing API description files and compiling a list of HTTP transactions to test.
verbose: Compiling HTTP transactions from API description file: ./api.apib
verbose: Starting reporters and waiting until all of them are ready.
info: Beginning Dredd testing...
verbose: Starting transaction runner.
verbose: Sorting HTTP transactions
verbose: Configuring HTTP transactions
verbose: Reading hook files and registering hooks
info: Found Hookfiles: 0=./tmp-hooks.js
verbose: Executing HTTP transactions
verbose: Running 'beforeAll' hooks
debug: Running hooks...

Can you send us failing test in a Pull Request?

Yes. You can also replicate with this:

tmp-hooks.js:

let hooks = require('hooks');
let express = require('express');

let server = express();
const PORT = 9311;

server.get('/', function(req, res) {
  res.json({message: 'Hello World!'});
});

hooks.beforeAll(function(transactions, done) {
  return server.listen(PORT, function() {
    // Never executes the following - just hangs
    console.log(`--- Server up and listening on port: ${PORT}`);
    return done();
  });
});

api.apib:

FORMAT: 1A

# GET /
+ Response 200 (application/json; charset=utf-8)

        {"message": "Hello World!"}

[justin-calleja]

Just found out about dredd init and its support for "command to start API backend server"... which basically solves this problem.

It's weird how the express server is hanging but this is no longer an issue for me if there's built-in support to do what I originally wanted.

[justin-calleja]

Update: it would be better if I could kick off Dredd testing after the test server is up. If I try to build my code and then run the test server (using the latest code), this takes longer than the default server-wait of 3 seconds in dredd-config.yml and the tests fail.

In order to avoid this, is there a way to start a server in beforeAll and then proceed with Dredd testing?

[honzajavorek]

@justin-calleja You can override that particular dredd.yml option by command line option in case you test locally during development. Would that work for you?

[justin-calleja]

@honzajavorek thanks for the quick reply :)

Unfortunately, no it doesn't work as there's the same problem (I have actually tried it). I want to avoid relying on a timeout and run tests when I'm sure that the server is up and running (that's why I want to do it programmatically via beforeAll).

[honzajavorek]

I didn't really try it out, but I see no reason why the beforeAll hook should hang if its callback gets ran. Only thing which comes to me from the top of my head is that Dredd doesn't really act on errors passed to the hook callback (which I consider a wrong behavior to be fixed), so if for some reason Express calls the callback with error, maybe the error gets silently passed or something. I can try to build a working example, but it might take some time.

[honzajavorek]

Just noticed you use ES2016 in the example you shared. Would you mind to try a minimal example with plain old ES5, just for the sake of eliminating options where the problem might be?

[justin-calleja]

@honzajavorek I am calling the hook callback myself in the Express server's listen callback i.e. once the server is up, I am calling done() to prceed with the tests. The problem is that execution is never entering the Express server's listen callback for some reason I can't figure out...

I have written an example repo to reproduce this:

https://github.com/justin-calleja/dredd-express-issue