Angular protractor how to check click with redirect condition

Be patient, I am new to the protractor.

I have this code:

angular.module('my.users')
    .controller('SessionSigninController', ['$scope', '$rootScope', 'Users', '$state',
        function($scope, $rootScope, Users, $state) {
            $scope.user = {};
            $scope.errors = [];
            $scope.save = function() {
                Users.signin($scope.user).then(
                    function(data) { 
                        if(data.success){
                            $rootScope.$emit('loggedin',data.user);
                            return $state.go('home');
                        }
                        $scope.errors = data.errors;
                    }
                );
            };
        }
    ])

      

        
        
        
      

    

I am testing it like (green bar):

describe('users :', function() {
    describe('register', function() {
        beforeEach(function() {
            browser.get('/#!/user/register');
        });
        it('btn should be disabled', function() {
            var btn = element(by.css('button.btn-primary'));
            expect(browser.isElementPresent(btn)).toBe(true);
            expect(btn.isEnabled()).toBe(false);
        });
        it('btn should be enabled', function() {
            var btn = element(by.css('button.btn-primary'));
            element(by.model('user.fullname')).sendKeys('test user');
            element(by.model('user.email')).sendKeys('test@etest.io');
            element(by.model('user.username')).sendKeys('testusere');
            element(by.model('user.password')).sendKeys('testsecret');
            element(by.model('user.password_confirmation')).sendKeys('testsecret');
            expect(browser.isElementPresent(btn)).toBe(true);
            expect(btn.isEnabled()).toBe(true);
            btn.click();
            expect(browser.getCurrentUrl()).toMatch(/\/#!/);

        });
    });

});

      

        
        
        
      

    

• Is this the correct way to test a "redirect" to a home?
• Why is the test green even if the form is invalid (unique email address)?
• Is there a way to mock the test?

END UP (see answer)

describe('users :', function() {
    describe('register', function() {
        beforeEach(function() {
            browser.get('/#!/user/register');
        });
        it('btn should be disabled', function() {
            var btn = element(by.css('button.btn-primary'));
            expect(browser.isElementPresent(btn)).toBe(true);
            expect(btn.isEnabled()).toBe(false);
        });
        it('btn should be enabled', function() {
            var random = ~~(Math.random() * 1000);
            var btn = element(by.css('button.btn-primary'));
            element(by.model('user.fullname')).sendKeys('test user');
            element(by.model('user.email')).sendKeys('test'+random+'@test.io');
            element(by.model('user.username')).sendKeys('testuser'+random);
            element(by.model('user.password')).sendKeys('testsecret');
            element(by.model('user.password_confirmation')).sendKeys('testsecret');
            expect(browser.isElementPresent(btn)).toBe(true);
            expect(btn.isEnabled()).toBe(true);
            btn.click();
            expect(browser.getCurrentUrl()).toMatch(/\/#!\/$/);
            var userMenu = element.all(by.css('ul.dropdown-menu li'));
            expect(userMenu.count()).toBe(3);
         });
    });

});