christian-schulze/bdd-lazy-var

Provides "ui" for mocha.js which allows to define lazy variables and subjects

Mocha BDD + lazy variable definition (aka rspec)

Provides "ui" for mocha.js which allows to define lazy variables and subjects.

Purpose

Stop writing

describe('Suite', function() {
  var name;

  beforeEach(function() {
    name = getName();
  });

  afterEach(function() {
    name = null;
  });

  it('uses name variable', function() {
    expect(name).to.exist;
  });

  it('does not use name but anyway it is created in beforeEach', function() {
    expect(1).to.equal(1);
  });
});

And just use lazy vars which are created only when accessed and cleared automatically after each test

describe('Suite', function() {
  def('name', function() {
    return getName();
  });

  it('uses name variable', function() {
    expect($name).to.exist
  });

  it('does not use name, so it is not created', function() {
    expect(1).to.equal(1);
  });
});

Installation

npm install bdd-lazy-var --save-dev

Browser versions: bdd_lazy_var.js, bdd_lazy_var_global.js, bdd_lazy_var_getter.js. Node versions: index.js, global.js, getter.js.

How to use

Command line: mocha -u bdd-lazy-var or in JavaScript:

var mocha = new Mocha({
  ui: 'bdd-lazy-var' // bdd-lazy-var/global or bdd-lazy-var/getter
});

If you run tests in browser, you need to require/load bdd_lazy_var*.js (i.e., bdd_lazy_var.js, bdd_lazy_var_getter.js or bdd_lazy_var_global.js) and then ui option for mocha should be bdd-lazy-var/global (or bdd-lazy-var/getter or bdd-lazy-var, depends on which you prefer).

So, in karma.config.js it looks like this:

// karma.config.js
module.exports = function(config) {
  config.set({
    // ....
    files: [
      // ....
      require.resolve('bdd-lazy-var/bdd_lazy_var_global');
    ],
    client: {
      mocha: {
        ui: 'bdd-lazy-var/global'
      }
    }
  });
}

Or regular mocha configuration:

let Mocha = require('mocha');
require('bdd-lazy-var/bdd_lazy_var_global');

let runner = new Mocha({
  ui: 'bdd-lazy-var/global'
});

runner.addFile('path/to/spec/file');
runner.run();

If you want to access vars using more readable form use bdd-lazy-var/global or bdd-lazy-var/getter ui.

Features

• all variables are defined lazily, so order doesn't matter.
• accessible also inside before, after callbacks
• subject accessor as an alias for def('subject', ...) and get('subject')
• named subjects to be more explicit
• ability to redefine parent's variable
• fallback to parent's variables
• fallback to parent's variable inside the same definition (i.e. subject inside subject definition will refer to parent's subject)
• all variables are cleaned after each test
• get.variable or get.definitionOf for creating getters for variables
• access variables using:
  • this.variableName (i.e. this.fullName)
  • get(variableName) (i.e. get('fullName'))
  • $variableName (i.e. $fullName, only with bdd-lazy-var/global)
  • get.variableName (i.e. get.fullName, only with bdd-lazy-var/getter)

For more information, follow this link.

Examples for bdd-lazy-var/global

describe('Array', function() {
  subject(function() {
    return [ 1, 2, 3 ];
  });

  it('has 3 elements by default', function() {
    expect($subject).to.have.length(3);
  });
});

Examples for bdd-lazy-var/getter

describe('Suite', function() {
  subject(function() {
    return new Suite();
  });

  it('has parent', function() {
    expect(get.subject).to.have.keys('parent');
  });
});

Examples for bdd-lazy-var

describe('Suite', function() {
  def('fullName', function() {
    return this.firstName + '+' + this.lastName;
  });

  def('firstName', 'BDD');
  def('lastName', 'Lazy variable');

  it('computes variables', function() {
    expect(get('fullName')).to.equal('BDD+Lazy variable');
  });

  describe('Nested suite', function() {
    def('fullName', function() {
      return get('fullName') + '!'; // get parent's "fullName" variable
    });

    it('gets parent variable', function() {
      expect(get('fullName')).to.equal('BDD+Lazy variable!');
    });
  });

  describe('Another nested suite', function() {
    def('lastName', 'Rocks!');

    it('redefines parent variable', function() {
      expect(get('fullName')).to.equal('BDD+Rocks!');
    });
  });

  describe('with subject', function() {
    subject(function() {
      return {};
    });

    it('defines subject', function() {
      expect(subject()).to.be.an('object');
    });

    it('can be retrieved via `this`', function() {
      expect(this.subject).to.equal(subject());
    });
  });
});