(function() {

  QUnit.module("Backbone.Events");

  QUnit.test("on and trigger", function(assert) {
    assert.expect(2);
    var obj = { counter: 0 };
    _.extend(obj,Backbone.Events);
    obj.on('event', function() { obj.counter += 1; });
    obj.trigger('event');
    assert.equal(obj.counter, 1, 'counter should be incremented.');
    obj.trigger('event');
    obj.trigger('event');
    obj.trigger('event');
    obj.trigger('event');
    assert.equal(obj.counter, 5, 'counter should be incremented five times.');
  });

  QUnit.test("binding and triggering multiple events", function(assert) {
    assert.expect(4);
    var obj = { counter: 0 };
    _.extend(obj, Backbone.Events);

    obj.on('a b c', function() { obj.counter += 1; });

    obj.trigger('a');
    assert.equal(obj.counter, 1);

    obj.trigger('a b');
    assert.equal(obj.counter, 3);

    obj.trigger('c');
    assert.equal(obj.counter, 4);

    obj.off('a c');
    obj.trigger('a b c');
    assert.equal(obj.counter, 5);
  });

  QUnit.test("binding and triggering with event maps", function(assert) {
    var obj = { counter: 0 };
    _.extend(obj, Backbone.Events);

    var increment = function() {
      this.counter += 1;
    };

    obj.on({
      a: increment,
      b: increment,
      c: increment
    }, obj);

    obj.trigger('a');
    assert.equal(obj.counter, 1);

    obj.trigger('a b');
    assert.equal(obj.counter, 3);

    obj.trigger('c');
    assert.equal(obj.counter, 4);

    obj.off({
      a: increment,
      c: increment
    }, obj);
    obj.trigger('a b c');
    assert.equal(obj.counter, 5);
  });

  QUnit.test("binding and triggering multiple event names with event maps", function(assert) {
    var obj = { counter: 0 };
    _.extend(obj, Backbone.Events);

    var increment = function() {
      this.counter += 1;
    };

    obj.on({
      'a b c': increment
    });

    obj.trigger('a');
    assert.equal(obj.counter, 1);

    obj.trigger('a b');
    assert.equal(obj.counter, 3);

    obj.trigger('c');
    assert.equal(obj.counter, 4);

    obj.off({
      'a c': increment
    });
    obj.trigger('a b c');
    assert.equal(obj.counter, 5);
  });

  QUnit.test("binding and trigger with event maps context", function(assert) {
    assert.expect(2);
    var obj = { counter: 0 };
    var context = {};
    _.extend(obj, Backbone.Events);

    obj.on({
        a: function() {
            assert.strictEqual(this, context, 'defaults `context` to `callback` param');
        }
    }, context).trigger('a');

    obj.off().on({
        a: function() {
            strictEqual(this, context, 'will not override explicit `context` param');
        }
    }, this, context).trigger('a');
  });

  QUnit.test("listenTo and stopListening", function(assert) {
    assert.expect(1);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    a.listenTo(b, 'all', function(){ assert.ok(true); });
    b.trigger('anything');
    a.listenTo(b, 'all', function(){ assert.ok(false); });
    a.stopListening();
    b.trigger('anything');
  });

  QUnit.test("listenTo and stopListening with event maps", function(assert) {
    assert.expect(4);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    var cb = function(){ assert.ok(true); };
    a.listenTo(b, {event: cb});
    b.trigger('event');
    a.listenTo(b, {event2: cb});
    b.on('event2', cb);
    a.stopListening(b, {event2: cb});
    b.trigger('event event2');
    a.stopListening();
    b.trigger('event event2');
  });

  QUnit.test("stopListening with omitted args", function(assert) {
    assert.expect(2);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    var cb = function () { assert.ok(true); };
    a.listenTo(b, 'event', cb);
    b.on('event', cb);
    a.listenTo(b, 'event2', cb);
    a.stopListening(null, {event: cb});
    b.trigger('event event2');
    b.off();
    a.listenTo(b, 'event event2', cb);
    a.stopListening(null, 'event');
    a.stopListening();
    b.trigger('event2');
  });

  QUnit.test("listenToOnce", function(assert) {
    assert.expect(2);
    // Same as the previous test, but we use once rather than having to explicitly unbind
    var obj = { counterA: 0, counterB: 0 };
    _.extend(obj, Backbone.Events);
    var incrA = function(){ obj.counterA += 1; obj.trigger('event'); };
    var incrB = function(){ obj.counterB += 1; };
    obj.listenToOnce(obj, 'event', incrA);
    obj.listenToOnce(obj, 'event', incrB);
    obj.trigger('event');
    assert.equal(obj.counterA, 1, 'counterA should have only been incremented once.');
    assert.equal(obj.counterB, 1, 'counterB should have only been incremented once.');
  });

  QUnit.test("listenToOnce and stopListening", function(assert) {
    assert.expect(1);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    a.listenToOnce(b, 'all', function() { assert.ok(true); });
    b.trigger('anything');
    b.trigger('anything');
    a.listenToOnce(b, 'all', function() { assert.ok(false); });
    a.stopListening();
    b.trigger('anything');
  });

  QUnit.test("listenTo, listenToOnce and stopListening", function(assert) {
    assert.expect(1);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    a.listenToOnce(b, 'all', function() { assert.ok(true); });
    b.trigger('anything');
    b.trigger('anything');
    a.listenTo(b, 'all', function() { assert.ok(false); });
    a.stopListening();
    b.trigger('anything');
  });

  QUnit.test("listenTo and stopListening with event maps", function(assert) {
    assert.expect(1);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    a.listenTo(b, {change: function(){ assert.ok(true); }});
    b.trigger('change');
    a.listenTo(b, {change: function(){ assert.ok(false); }});
    a.stopListening();
    b.trigger('change');
  });

  QUnit.test("listenTo yourself", function(assert) {
    assert.expect(1);
    var e = _.extend({}, Backbone.Events);
    e.listenTo(e, "foo", function(){ assert.ok(true); });
    e.trigger("foo");
  });

  QUnit.test("listenTo yourself cleans yourself up with stopListening", function(assert) {
    assert.expect(1);
    var e = _.extend({}, Backbone.Events);
    e.listenTo(e, "foo", function(){ assert.ok(true); });
    e.trigger("foo");
    e.stopListening();
    e.trigger("foo");
  });

  QUnit.test("stopListening cleans up references", function(assert) {
    assert.expect(12);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    var fn = function() {};
    b.on('event', fn);
    a.listenTo(b, 'event', fn).stopListening();
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._events.event), 1);
    assert.equal(_.size(b._listeners), 0);
    a.listenTo(b, 'event', fn).stopListening(b);
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._events.event), 1);
    assert.equal(_.size(b._listeners), 0);
    a.listenTo(b, 'event', fn).stopListening(b, 'event');
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._events.event), 1);
    assert.equal(_.size(b._listeners), 0);
    a.listenTo(b, 'event', fn).stopListening(b, 'event', fn);
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._events.event), 1);
    assert.equal(_.size(b._listeners), 0);
  });

  QUnit.test("stopListening cleans up references from listenToOnce", function(assert) {
    assert.expect(12);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    var fn = function() {};
    b.on('event', fn);
    a.listenToOnce(b, 'event', fn).stopListening();
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._events.event), 1);
    assert.equal(_.size(b._listeners), 0);
    a.listenToOnce(b, 'event', fn).stopListening(b);
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._events.event), 1);
    assert.equal(_.size(b._listeners), 0);
    a.listenToOnce(b, 'event', fn).stopListening(b, 'event');
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._events.event), 1);
    assert.equal(_.size(b._listeners), 0);
    a.listenToOnce(b, 'event', fn).stopListening(b, 'event', fn);
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._events.event), 1);
    assert.equal(_.size(b._listeners), 0);
  });

  QUnit.test("listenTo and off cleaning up references", function(assert) {
    assert.expect(8);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    var fn = function() {};
    a.listenTo(b, 'event', fn);
    b.off();
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._listeners), 0);
    a.listenTo(b, 'event', fn);
    b.off('event');
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._listeners), 0);
    a.listenTo(b, 'event', fn);
    b.off(null, fn);
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._listeners), 0);
    a.listenTo(b, 'event', fn);
    b.off(null, null, a);
    assert.equal(_.size(a._listeningTo), 0);
    assert.equal(_.size(b._listeners), 0);
  });

  QUnit.test("listenTo and stopListening cleaning up references", function(assert) {
    assert.expect(2);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    a.listenTo(b, 'all', function(){ assert.ok(true); });
    b.trigger('anything');
    a.listenTo(b, 'other', function(){ assert.ok(false); });
    a.stopListening(b, 'other');
    a.stopListening(b, 'all');
    assert.equal(_.size(a._listeningTo), 0);
  });

  QUnit.test("listenToOnce without context cleans up references after the event has fired", function(assert) {
    assert.expect(2);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    a.listenToOnce(b, 'all', function(){ assert.ok(true); });
    b.trigger('anything');
    assert.equal(_.size(a._listeningTo), 0);
  });

  QUnit.test("listenToOnce with event maps cleans up references", function(assert) {
    assert.expect(2);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    a.listenToOnce(b, {
      one: function() { assert.ok(true); },
      two: function() { assert.ok(false); }
    });
    b.trigger('one');
    assert.equal(_.size(a._listeningTo), 1);
  });

  QUnit.test("listenToOnce with event maps binds the correct `this`", function(assert) {
    assert.expect(1);
    var a = _.extend({}, Backbone.Events);
    var b = _.extend({}, Backbone.Events);
    a.listenToOnce(b, {
      one: function() { assert.ok(this === a); },
      two: function() { assert.ok(false); }
    });
    b.trigger('one');
  });

  QUnit.test("listenTo with empty callback doesn't throw an error", function(assert) {
    assert.expect(1);
    var e = _.extend({}, Backbone.Events);
    e.listenTo(e, "foo", null);
    e.trigger("foo");
    assert.ok(true);
  });

  QUnit.test("trigger all for each event", function(assert) {
    assert.expect(3);
    var a, b, obj = { counter: 0 };
    _.extend(obj, Backbone.Events);
    obj.on('all', function(event) {
      obj.counter++;
      if (event == 'a') a = true;
      if (event == 'b') b = true;
    })
    .trigger('a b');
    assert.ok(a);
    assert.ok(b);
    assert.equal(obj.counter, 2);
  });

  QUnit.test("on, then unbind all functions", function(assert) {
    assert.expect(1);
    var obj = { counter: 0 };
    _.extend(obj,Backbone.Events);
    var callback = function() { obj.counter += 1; };
    obj.on('event', callback);
    obj.trigger('event');
    obj.off('event');
    obj.trigger('event');
    assert.equal(obj.counter, 1, 'counter should have only been incremented once.');
  });

  QUnit.test("bind two callbacks, unbind only one", function(assert) {
    assert.expect(2);
    var obj = { counterA: 0, counterB: 0 };
    _.extend(obj,Backbone.Events);
    var callback = function() { obj.counterA += 1; };
    obj.on('event', callback);
    obj.on('event', function() { obj.counterB += 1; });
    obj.trigger('event');
    obj.off('event', callback);
    obj.trigger('event');
    assert.equal(obj.counterA, 1, 'counterA should have only been incremented once.');
    assert.equal(obj.counterB, 2, 'counterB should have been incremented twice.');
  });

  QUnit.test("unbind a callback in the midst of it firing", function(assert) {
    assert.expect(1);
    var obj = {counter: 0};
    _.extend(obj, Backbone.Events);
    var callback = function() {
      obj.counter += 1;
      obj.off('event', callback);
    };
    obj.on('event', callback);
    obj.trigger('event');
    obj.trigger('event');
    obj.trigger('event');
    assert.equal(obj.counter, 1, 'the callback should have been unbound.');
  });

  QUnit.test("two binds that unbind themeselves", function(assert) {
    assert.expect(2);
    var obj = { counterA: 0, counterB: 0 };
    _.extend(obj,Backbone.Events);
    var incrA = function(){ obj.counterA += 1; obj.off('event', incrA); };
    var incrB = function(){ obj.counterB += 1; obj.off('event', incrB); };
    obj.on('event', incrA);
    obj.on('event', incrB);
    obj.trigger('event');
    obj.trigger('event');
    obj.trigger('event');
    assert.equal(obj.counterA, 1, 'counterA should have only been incremented once.');
    assert.equal(obj.counterB, 1, 'counterB should have only been incremented once.');
  });

  QUnit.test("bind a callback with a supplied context", function(assert) {
    assert.expect(1);
    var TestClass = function () {
      return this;
    };
    TestClass.prototype.assertTrue = function () {
      assert.ok(true, '`this` was bound to the callback');
    };

    var obj = _.extend({},Backbone.Events);
    obj.on('event', function () { this.assertTrue(); }, (new TestClass));
    obj.trigger('event');
  });

  QUnit.test("nested trigger with unbind", function(assert) {
    assert.expect(1);
    var obj = { counter: 0 };
    _.extend(obj, Backbone.Events);
    var incr1 = function(){ obj.counter += 1; obj.off('event', incr1); obj.trigger('event'); };
    var incr2 = function(){ obj.counter += 1; };
    obj.on('event', incr1);
    obj.on('event', incr2);
    obj.trigger('event');
    assert.equal(obj.counter, 3, 'counter should have been incremented three times');
  });

  QUnit.test("callback list is not altered during trigger", function(assert) {
    assert.expect(2);
    var counter = 0, obj = _.extend({}, Backbone.Events);
    var incr = function(){ counter++; };
    var incrOn = function(){ obj.on('event all', incr); };
    var incrOff = function(){ obj.off('event all', incr); };

    obj.on('event all', incrOn).trigger('event');
    assert.equal(counter, 0, 'on does not alter callback list');

    obj.off().on('event', incrOff).on('event all', incr).trigger('event');
    assert.equal(counter, 2, 'off does not alter callback list');
  });

  QUnit.test("#1282 - 'all' callback list is retrieved after each event.", function(assert) {
    assert.expect(1);
    var counter = 0;
    var obj = _.extend({}, Backbone.Events);
    var incr = function(){ counter++; };
    obj.on('x', function() {
      obj.on('y', incr).on('all', incr);
    })
    .trigger('x y');
    assert.strictEqual(counter, 2);
  });

  QUnit.test("if no callback is provided, `on` is a noop", function(assert) {
    assert.expect(0);
    _.extend({}, Backbone.Events).on('test').trigger('test');
  });

  QUnit.test("if callback is truthy but not a function, `on` should throw an error just like jQuery", function(assert) {
    assert.expect(1);
    var view = _.extend({}, Backbone.Events).on('test', 'noop');
    assert.throws(function() {
      view.trigger('test');
    });
  });

  QUnit.test("remove all events for a specific context", function(assert) {
    assert.expect(4);
    var obj = _.extend({}, Backbone.Events);
    obj.on('x y all', function() { assert.ok(true); });
    obj.on('x y all', function() { assert.ok(false); }, obj);
    obj.off(null, null, obj);
    obj.trigger('x y');
  });

  QUnit.test("remove all events for a specific callback", function(assert) {
    assert.expect(4);
    var obj = _.extend({}, Backbone.Events);
    var success = function() { assert.ok(true); };
    var fail = function() { assert.ok(false); };
    obj.on('x y all', success);
    obj.on('x y all', fail);
    obj.off(null, fail);
    obj.trigger('x y');
  });

  QUnit.test("#1310 - off does not skip consecutive events", function(assert) {
    assert.expect(0);
    var obj = _.extend({}, Backbone.Events);
    obj.on('event', function() { assert.ok(false); }, obj);
    obj.on('event', function() { assert.ok(false); }, obj);
    obj.off(null, null, obj);
    obj.trigger('event');
  });

  QUnit.test("once", function(assert) {
    assert.expect(2);
    // Same as the previous test, but we use once rather than having to explicitly unbind
    var obj = { counterA: 0, counterB: 0 };
    _.extend(obj, Backbone.Events);
    var incrA = function(){ obj.counterA += 1; obj.trigger('event'); };
    var incrB = function(){ obj.counterB += 1; };
    obj.once('event', incrA);
    obj.once('event', incrB);
    obj.trigger('event');
    assert.equal(obj.counterA, 1, 'counterA should have only been incremented once.');
    assert.equal(obj.counterB, 1, 'counterB should have only been incremented once.');
  });

  QUnit.test("once variant one", function(assert) {
    assert.expect(3);
    var f = function(){ assert.ok(true); };

    var a = _.extend({}, Backbone.Events).once('event', f);
    var b = _.extend({}, Backbone.Events).on('event', f);

    a.trigger('event');

    b.trigger('event');
    b.trigger('event');
  });

  QUnit.test("once variant two", function(assert) {
    assert.expect(3);
    var f = function(){ assert.ok(true); };
    var obj = _.extend({}, Backbone.Events);

    obj
      .once('event', f)
      .on('event', f)
      .trigger('event')
      .trigger('event');
  });

  QUnit.test("once with off", function(assert) {
    assert.expect(0);
    var f = function(){ assert.ok(true); };
    var obj = _.extend({}, Backbone.Events);

    obj.once('event', f);
    obj.off('event', f);
    obj.trigger('event');
  });

  QUnit.test("once with event maps", function(assert) {
    var obj = { counter: 0 };
    _.extend(obj, Backbone.Events);

    var increment = function() {
      this.counter += 1;
    };

    obj.once({
      a: increment,
      b: increment,
      c: increment
    }, obj);

    obj.trigger('a');
    assert.equal(obj.counter, 1);

    obj.trigger('a b');
    assert.equal(obj.counter, 2);

    obj.trigger('c');
    assert.equal(obj.counter, 3);

    obj.trigger('a b c');
    assert.equal(obj.counter, 3);
  });

  QUnit.test("once with off only by context", function(assert) {
    assert.expect(0);
    var context = {};
    var obj = _.extend({}, Backbone.Events);
    obj.once('event', function(){ assert.ok(false); }, context);
    obj.off(null, null, context);
    obj.trigger('event');
  });

  QUnit.test("Backbone object inherits Events", function(assert) {
    assert.ok(Backbone.on === Backbone.Events.on);
  });

  QUnit.test("once with asynchronous events", function(assert) {
    var done = assert.async();
    assert.expect(1);
    var func = _.debounce(function() { assert.ok(true); done(); }, 50);
    var obj = _.extend({}, Backbone.Events).once('async', func);

    obj.trigger('async');
    obj.trigger('async');
  });

  QUnit.test("once with multiple events.", function(assert) {
    assert.expect(2);
    var obj = _.extend({}, Backbone.Events);
    obj.once('x y', function() { assert.ok(true); });
    obj.trigger('x y');
  });

  QUnit.test("Off during iteration with once.", function(assert) {
    assert.expect(2);
    var obj = _.extend({}, Backbone.Events);
    var f = function(){ this.off('event', f); };
    obj.on('event', f);
    obj.once('event', function(){});
    obj.on('event', function(){ assert.ok(true); });

    obj.trigger('event');
    obj.trigger('event');
  });

  QUnit.test("`once` on `all` should work as expected", function(assert) {
    assert.expect(1);
    Backbone.once('all', function() {
      assert.ok(true);
      Backbone.trigger('all');
    });
    Backbone.trigger('all');
  });

  QUnit.test("once without a callback is a noop", function(assert) {
    assert.expect(0);
    _.extend({}, Backbone.Events).once('event').trigger('event');
  });

  QUnit.test("listenToOnce without a callback is a noop", function(assert) {
    assert.expect(0);
    var obj = _.extend({}, Backbone.Events);
    obj.listenToOnce(obj, 'event').trigger('event');
  });

  QUnit.test("event functions are chainable", function(assert) {
    var obj = _.extend({}, Backbone.Events);
    var obj2 = _.extend({}, Backbone.Events);
    var fn = function() {};
    assert.equal(obj, obj.trigger('noeventssetyet'));
    assert.equal(obj, obj.off('noeventssetyet'));
    assert.equal(obj, obj.stopListening('noeventssetyet'));
    assert.equal(obj, obj.on('a', fn));
    assert.equal(obj, obj.once('c', fn));
    assert.equal(obj, obj.trigger('a'));
    assert.equal(obj, obj.listenTo(obj2, 'a', fn));
    assert.equal(obj, obj.listenToOnce(obj2, 'b', fn));
    assert.equal(obj, obj.off('a c'));
    assert.equal(obj, obj.stopListening(obj2, 'a'));
    assert.equal(obj, obj.stopListening());
  });

  QUnit.test("#3448 - listenToOnce with space-separated events", function(assert) {
    assert.expect(2);
    var one = _.extend({}, Backbone.Events);
    var two = _.extend({}, Backbone.Events);
    var count = 1;
    one.listenToOnce(two, 'x y', function(n) { assert.ok(n === count++); });
    two.trigger('x', 1);
    two.trigger('x', 1);
    two.trigger('y', 2);
    two.trigger('y', 2);
  });

})();