Ddry NPM | npm.io

ddry

Data-driven DRY wrapper for Node JS testing. Supports Mocha, Tape and Selenium Webdriver

Brief introduction

ddry (Data-Driven Don't Repeat Yourself) JS testing wrapper is made to remove all the error-prone code clutter from testing.

Developers should not be distracted by requireing target code modules for testing or assertion libraries or even — please just read it carefully — debugging test suites. Testing appears to be more about validating data processing performed by tested modules methods, not about code you need to write to test some other code.

Well, we already have our code modules structure. Why invent their specs structure with messy requireing?

With ddry you simply (convention-over-configuration) organize your spec folder similar to your code folder, where module spec folder structure resembles module properties and methods structure, and in spec/someFolder/someModule/someMethod.js file you have the context of someMethod of someModule without any requiring — ddry does it for you seamlessly and transparently. Then in this way placed file

(here and further we use coffee for its awesome object syntax)

'use strict'

module.exports = (dd) ->
  dd.drive [
    it: 'does everything correctly'
    i: [ 'arguments', 'a', 'method', 'receives' ]
    e: 'value it returns'
  ]

And that's it. i is for input, e is for expected. Let's keep focused on data flow. Pray excuse me who think that require, assert, expect etc. are the essence of testing.

This data-driven code will be adapted and passed by ddry to any of three JS test harnesses: Mocha JS, TAP or Tape JS to perform actual testing. ddry itself is fully covered on all of them with unified harness-agnostic codebase.

And yet every ddry spec remains conventional JS module where you can write your JS the way you like.

# spec/someFolder/someModule/someMethod.coffee

###
# Module title recognizable by `ddry titles` command
###

'use strict'

module.exports = (dd, that) -> # `dd` is ddry instance, `that` is someModule
  method = that.someMethod

  # testing context creation omitted

  actual = method 'arguments', 'a', 'method', 'receives'
  dd.drive
    matcher: 'plain'
    it: 'does everything correctly'
    i: actual
    e: 'value it returns'
    
  # cleanup omitted

is, of course, possible. And, of course, you can require whatever assertion instruments you need and use them. And, of course, whatever you can do with JS.

Also ddry has:

cross-harness features: context, before/after hooks and x-style skipping and mass-skipping;
powerful default matchers set including plain, contains and error and easy custom matchers adding;
spec sequence syntax allowing to use one setting through multiple specs;
convention-over-configuration folder-style module instances support;
easily configurable instantiable attachable spec helper;
Selenium Webdriver support (with Mocha only);
ddry shell command to maintain the project spec config file ddry.json;
test harness specific shell commands ddry-mocha, ddry-tap and ddry-tape to comfortly run the specs of your choice against test harness of your choice;
some cute minor features.

Plainly, a decent set of capabilities to make JS testing easy and even fun.

ddry command line interface

ddry CLI gives you convenient access to your data-driven specs by

keeping their config in ddry.json file;
implementing powerful features for maintaining this config file;
applying only-except style suite running scope with one shell command.

Only-except scoping logic is applicable to modules folders, modules and module methods levels.

In your development environment you may want to get easy access to ddry shell command by installing ddry globally:

$ sudo npm i -g ddry

ddry shell command is just a spec configuring tool, it does not perform any actual testing which is task of harness-specific commands as well as spec suite execution scoping.

Optional dependencies and spec suite execution scoping

ddry core just implements javascript.dot.notated.object.syntax to spec/modules/and/folders/and/methods/filenames permutation magic, some cross-harness features and matchers setup. To run actual tests it needs at least one real JS test harness that ddry knows about: Mocha JS, TAP, or Tape JS. Here we come to the strange concept of optional dependency.

There are four packages to solve this problem by adding viable devDependencies set — ddry core and test harness(es) — to package.json and implementing harness-specific shell command(s) — ddry-mocha, ddry-tap and ddry-tape:

ddry-mocha for Mocha JS;
ddry-tap for TAP;
ddry-tape for Tape JS;
ddry-mocha-tape mounting all the supported harnesses.

To run the spec configured by ddry.json from within the test harness of your choice just pass to it the ./node_modules/ddry/ddry.js file. Please check Makefile of any of these packages for examples.

Any of test harness specific shell commands — ddry-mocha, ddry-tap and ddry-tape — without parameters will launch the entire suite configured in ddry.json against its test harness.

Use -e and -o keys for except and only scoping strategies applied to tab-completed code or spec files or folders. Inside code folder you have access to module folders and module level, inside spec folder you may scope method-wise. Keys you use with ddry-<mocha|tap|tape> command will have effect only once, while this shell command runs.

To manage permanent scopes in ddry.json you may use $ ddry as and $ ddry rs commands — they will translate to config object style (dot-notated, by the way) your tab-completed findings.

Further ddry CLI shell commands usage details are subject of these four packages documentation.

Getting started with ddry

Please check ddry-guide project containing checkoutable step-by-step way from blank Node JS project to all the features demo, including support of major Javascript module concepts, CI setup and testing with Selenium Webdriver. With setup process described there, here we'll focus on data-driven testing core features details.

Data-driven DRY testing wrapper features documentation

Here's the brief list of data-driven testing core features in order of their appearance in ddry-guide:

Prerequisites
Getting started
Convention over configuration spec folder structure
Injected ddry instance — dd
plain matcher
default matcher
Sequences
Sequence specs
Spec sequences. Cross-harness x-style skipping and mass skipping
CoffeeScript Sublime Text snippets
Injected target module context — that
property matcher;
cross-harness context;
cross-harness before and after hooks;
spec helper;
dd.ry deep parameterizer method;
function export module support;
module instances support;
Selenium Webdriver specs;
only-except scopes of all levels;
test harness scope;
outside modules.

We'll develop all these subjects documentation gradually.

ddry development (CONTRIBUTING.md draft)

While the work on main documentation is in progress, the only source of data-driven testing features and techniques is project code itself.

Installation

After cloning this repo please check global installations of coffee-script and phantomjs-prebuilt.

Before running the test suite start project watcher responsible for CoffeeScript compiling and running brunch web server being used for Selenium Webdriver related ddry features testing:

$ make c-w

First run can take some time to assemble brunch project, then later it'll simply start brunch server.

Running test suite

You'll need ddry, ddry-mocha, ddry-tap and ddry-tape shell commands, please install ddry and ddry-mocha-tape globally.

Then you'll be able to init cli.json ddry system file storing module paths for scoping and spec suite CLI constraints:

$ ddry t

Then make tasks named mocha, tap and tape will give you (probably passing) tests against these harnesses, and test task runs the entire test suite against all of them. mocha task also generates coverage object.

Internal mechanics of ddry fully covered by ddry

All the tests that fully cover this project are written with this project. That is a little bit complicated, but let's make it clear.

First of all, ddry has itself as devDependency through ddry-mocha-tape, and in main test suite configuration project code is tested by project version published to NPM and installed to node_modules — in terms of ddry core responsible for data-driven specs code parsing and ddry CLI responsible for unobtrusive testing configuring with ddry.json and comfortable filtering of specs you wish to run right this time.

This way we have two very important switchable parameters:

location of ddry core;
location of ddry CLI.

For ddry core we have three options:

project root code (named ddry);
project NPM-published version of code (named npmv);
switchable project edge code (named edge).

Edge code is just a copy of project code compiled to edge_package/ddry/ folder (to mimic node_modules/ddry/ depth level). Using edge version for testing is rather discouraged, it is only for implementing major core features that make usual ddry by npmv testing utterly impossible. This copy is invoked by make ce-w command and removed by make c-w command.

Specs suite configuration (unobtrusively stored in ddry.json) for these three cases should obviously be different. This circumstance inspired ddry config command feature enabling creation of configuration object by JS module. Configurer module for ddry is spec/config and it creates configurations for testing any project code instance against any other instance.

Another cool feature of ddry config (or ddry c) command is that once you set the configurer module path, you may omit it since that. It's pretty obvious that we can generate any number of different configs inside one configurer and we definitely do not need more than one configurer.

spec/config knows ddry, edge and npmv as d, e and n respectively and sets nd by default that means testing of project root code ddry by published and installed version npmv. Combine these three letters in all possible harness-subject combinations (ddry c ne, ddry c dn etc.) and get some accompanying issues. With solid relative prefix fallback strategy all combinations run smoothly, i.e. yield reasonable failures (most common: specs of new features normally fail on published version).

For ddry CLI we have two options:

published and installed to node_modules (default);
from project root.

Usually we pass to test harness ./node_modules/ddry/ddry.js to run specs configured by ddry.json. But if we need to edit ddry.coffee source and run it, we need to pass to harnesses ddry.js from project root. Simply

$ export DDRY_DEV=whatever

to switch to development CLI. Set really whatever, ddry CLI checks only whether DDRY_DEV is defined. So, to switch back to normal

$ unset DDRY_DEV

Makefile uses tiny scripts setting JS filename appropriate to chosen environment.

After switching CLI you have to specify configurer path again for modules requiring it are placed differently:

$ ddry c spec/config

And then initialize cli.json for newly chosen CLI instance:

$ ddry t

Practice makes intermediate, so after some time these switches can become funny toys for you. But the first time their description surely looks like incomprehesible TL;DR babbling.

ddry core internal mechanics

There are four JS files in project root, let's briefly describe them all:

index.js — the deepest core of the project, it requires all the lib/ folder except lib/cli to do all the convention over configuration magic to create required target code module method context in certain file in specs folder and parse the data-driven syntax of dd.drive command to pass actual test data to real test harnesses. It is aware of module, method and data-driven spec syntax, but doesn't care about the whole test suite.

modular.js — first index.js wrapper made to organize testing at the entire suite level. It is aware of spec suite config and all the tested modules, inside code folder and even outside (it's the name of advanced but intuitively graspable config option). It is also aware of all the rest advanced config options, including custom matchers, Selenium drivers to use, suite execution only/except scopes of all levels (module folder, module and module method), test harnesses scopes etc.

ddry.js — modular.js wrapper allowing suite execution only-except style scoping without editing spec config in and out. It is also a service point file for all the test harnesses to make testing configured in ddry.json file. It determines whether it is launched from ddry shell command of from within a test harness and delivers the suite entirely or within scope defined by CLI.

cli.js — CLI commands and scopes parser. Updates ddry.json when executing commands, updates cli.json for only-this-run scope constraints. Outputs usage info. Throws error when needs to prevent test harness launch. Exits normally to allow it.