sign-in-test.js

  describe('Validations', function() {
    before(function() {
      this.alert = stub(window, 'alert');
    });

    after(function() {
      this.alert.restore();
    });

    it('validates password', function() {
      var test = this;
      expect(2);

      visit('/tab/planning/sign-in');
      fillIn('input.email', 'example@example.com');
      click('button.signin');

      andThen(function() {
        expect(test.alert.called).to.eql(1);
        expect(test.alert.calledWith[0][0]).to.match(/.*must.*password.*/i);
      });
    });

    it('validates email', function() {
      var test = this;
      expect(2);

      visit('/tab/planning/sign-in');
      fillIn('input.password', 'password');
      click('button.signin');

      andThen(function() {
        expect(test.alert.called).to.eql(1);
        expect(test.alert.calledWith[0][0]).to.match(/.*must.*email.*/i);
      });
    });
  });

stub.js

export default function (obj, name, value) {
  var original = obj[name];

  obj[name] = function() {
    obj[name].called++;
    obj[name].calledWith.push(arguments);
    return value;
  };

  obj[name].restore = function() {
    obj[name] = original;
  };

  obj[name].called = 0;
  obj[name].calledWith = [];

  return obj[name];
}