depends-on

depends-on

Spins up external processes your tests need. Think of it as async.auto with process control for integration tests.

example:

{
  "redis": {
    "cmd": ["/usr/sbin/redis-server"],
    "wait_for": {
      "port": 6379
    }
  }
}

var ready = require('depends-on')('redis');
var test = require('tape');

test('init', ready);

< … tests that use redis here … >

ready() is a function that takes a callback (or a tape test object). It will call that callback when your dependencies are ready. They'll be stopped when your node process exits.

Dependencies can have dependencies. Say you want to clear all values from Redis after it starts, but before your tests run:

{
  "redis-server": {
    "cmd": ["/usr/sbin/redis-server"],
    "wait_for": {
      "port": 6379
    }
  },
  "fresh & clean redis": {
    "cmd": ["./bin/flushall.sh"],
    "depends": ["redis-server"],
    "wait_for": {
      "exit_code": 0
    }
  }
}

var ready = require('depends-on')('fresh & clean redis');
var test = require('tape');

test('start fresh redis', ready);

test('test that uses redis', function(t) {
  …
});
…

If multiple tests are require()d and share dependencies, depends-on will share them across the test files, each dependency only being started once. When node exits, all dependencies will exit.

dependencies.json

dependencies.json is a file containing a json object mapping dependency names to objects that describe each dependency.

dependency fields

cmd

array of command and args for child_process.spawn (required)

depends

array of names of dependencies which this dependency depends on

cwd

The cwd to pass to child_process.spawn

stdout

path to log dependency's stdout to (default: your stdout)

stderr

path to log dependency's stderr to (default: your stderr)

signal

signal to use to tell the dependency to shut down (default: `SIGTERM`)

wait_for

lets you specify an ip:port and timeout to wait for socket availability before considering a dependency started

wait_for fields

One of port or exit_code is required to use wait_for.

host

default: localhost

port

if port is set, will wait for a TCP connection to be accepted on this port

exit_code

if exit_code is set, will wait for the process to exit with this code before proceeding

timeout

seconds to wait before considering a dependency to have failed starting up (default: 30)

graph dependencies

Just for fun, bin/graph-dependencies.js can graph the dependencies in your project with graphviz.

dot -Tpng -odeps.png <(./bin/graph-dependencies.js) && open deps.png ->

notes

using with tape

Be sure to require('depends-on') before you require('tape'). Like this:

var ready = require('depends-on')('something');
var test = require('tape');

Both depends-on and tape have process.on('exit', …) handlers, but tape calls process.exit in its process.on('exit', …) handler, so if tape's handler runs first, depends-on's handler will never run (and child processes won't be cleaned up). Handlers run in the order they are added, so depends-on must be required first.

why not use a bash script or Makefile?

I like to be able to run integration tests individually like $ node tests.js without running anything else or relying on some external service coincidentally being on.