How to write you own testing library

[Lukasz Bandzarewicz]

[Lukasz Bandzarewicz]

Initial work

function Suite(message, parent) {
  this.message = message;
  this.parent = parent;

  this.tests = [];
}

Suite.prototype.fullMessage = function() {
  var messages = [this.message];
  if (this.parent) {
    messages.unshift(this.parent.fullMessage());
  }

  return messages.join(' ');
};

function Test(message, parent, fn) {
  this.message = message;
  this.parent = parent;
  this.fn = fn;
}

Test.prototype.fullMessage = function() {
  var messages = [this.parent.fullMessage(), this.message];
  return messages.join(' ');
};

var suites = [];

function describe(message, fn) {
  var parent = suites[suites.length - 1];
  var suite = new Suite(message, parent);

  suites.push(suite);
  fn.call(suite);
}

function it(message, fn) {
  var parent = suites[suites.length - 1];
  var scenario = new Test(message, parent, fn);
  parent.tests.push(scenario);
}

function run() {
  suites.forEach(function(suite) {
    suite.tests.forEach(function(test) {
      try {
        test.fn.call(test);
        console.log('OK:   ', test.fullMessage());
      } catch(error) {
        console.log('ERROR:', test.fullMessage());
        console.log(error.message);
        console.log(error.stack);
      }
    });
  });
}

function assert(condition, message) {
  if (!condition) {
    throw new Error(message);
  }
}

describe('Suite', function() {

  describe('.message', function() {

    var suite = this;

    it('returns a message', function() {
      assert(suite.message === '.message');
    });

  });

  describe('.fullMessage()', function() {

    var suite = this;

    it('returns the full message', function() {
      assert(suite.fullMessage() === 'Suite .fullMessage()');
    });

  });

});

describe('Test', function() {

  describe('.message', function() {

    it('returns a test message', function() {
      var test = this;
      assert(test.message === 'returns a test message');
    });

  });

  describe('.fullMessage()', function() {

    it('returns the full test message', function() {
      var test = this;
      assert(test.fullMessage() === 'Test .fullMessage() returns a test message');
    });

  });

});

run();