ectypes

ectypes

A way to produce test objects quickly with any persistence layer.

The Name

ectype (plural ectypes) (philosophy) A copy; usually contrasted with the original, or archetype.  

As opposed to prototype, ectype originally meant “wrought in relief” in Greek. Its roots are ec, a variant of “ex,” and týpos, a “figure on a wall.”

Installation

npm install ectypes

Explanation: Contexts, Strategies and Blueprints.

Ectypes is a DSL for building persistable data types and describing how they should be filled with data. If you've ever used factory_girl or machinist (Ruby testing libraries) the concept will be familiar to you.

Ectypes uses a strategy to identify how to talk to whichever persistence layer you've chosen to use (mongodb, relational db, redis, whatever);

var ectypes = require('ectypes')
  , ctx = require('./../lib/ectypes').createContext()
  , SimpleStrategy = require('./simple-strategy');

ctx.load(new SimpleStrategy());

Ectype contexts take blueprints of data types, and sets them up in the context.

var projectBlueprint = {
	Project: {
		title: function(){ return Faker.Name.findName() }
	}
};

ctx.add(projectBlueprint);

This blueprint could have held any amount of object descriptions.

Every function on the strategy (except for what is listed in an ignores array) is then mapped to the type, for example

ctx.Project.build(function(err, project){ 
  console.log(project.title); //gives 'Elaina Orn', a value produced by the Faker library.
});

In the above example, the simpleStrategy has defined a build(modelName, values) function, which ectypes will invoke, returning what it returns.

Alternately, if you wanted to override the value of the title in some circumstances:

ctx.Project.build({title: 'Someone else'}, function(err, project){ 
  console.log(project.title); //gives 'Someone else'
});

In the above, if the first argument to a strategy call is an object, any values it contains will be used to override the generated ones. If it's a function then it's assumed to be the conventional Node.js callback function(err, result).

It is up to you, when writing the strategy, what behaviours you want to support.

Writing Strategies

Ectypes uses a strategy pattern to specify proxied calls to whichever underlying persistence layer(s) you might like to use - they're very simple to write.

Current strategies:

ectypes-sequelize - http://github.com/nicholasf/ectypes-sequelize.js (for Sequelize - http://www.sequelizejs.com/). - This is only compatible with 0.0.5 and earlier versions of ectypes.

If you write one, please let me know.

Running Tests

mocha tests/ectypes-test.js 

More Info

Ectypes originally worked for Backbone.js. So it is possible to enable this testing for browser based development. If anyone wants to discuss it, let me know.