backoff-web/tests/fibonacci_backoff_strategy.js

Fibonacci and exponential backoffs.

var FibonacciBackoffStrategy = require('../src/strategy/fibonacci');

exports['FibonacciBackoffStrategy'] = {
  setUp: function (callback) {
    this.strategy = new FibonacciBackoffStrategy({
      initialDelay: 10,
      maxDelay: 1000
    });
    callback();
  },

  'backoff delays should follow a Fibonacci sequence': function (test) {
    // Fibonacci sequence: x[i] = x[i-1] + x[i-2].
    var expectedDelays = [10, 10, 20, 30, 50, 80, 130, 210, 340, 550, 890, 1000];
    var actualDelays = [];

    for (var i = 0; i < expectedDelays.length; i++) {
      actualDelays.push(this.strategy.next());
    }

    test.deepEqual(expectedDelays, actualDelays,
      'Generated delays should follow a Fibonacci sequence.');
    test.done();
  },

  'backoff delays should restart from the initial delay after reset': function (test) {
    var strategy = new FibonacciBackoffStrategy({
      initialDelay: 10,
      maxDelay: 1000
    });

    strategy.next();
    strategy.reset();

    var backoffDelay = strategy.next();
    test.equals(backoffDelay, 10,
      'Strategy should return the initial delay after reset.');
    test.done();
  }
};