Package Exports

bdd-lazy-var

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Readme

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());
    });
  });
});

bdd-lazy-var