AngularJS Custom Float Validation

ValidateFloat.js

'use strict';

/**
 * This directive parses both 1.2 and 1,2 into a valid float number 1.2.
 * Note that you can't use input type number here as HTML5 browsers would
 * not allow the user to type what it would consider an invalid number such as 1,2.
 *
 * <input ng-model="{yourModel}" validate-float />
 */
angular.module('Library').directive('validateFloat', function () {
    
    var FLOAT_REGEXP = /^\-?\d+((\.|\,)\d+)?$/;
    
    return {
        require: "ngModel",
        link: function(scope, elm, attrs, ngModelController){

            ngModelController.$parsers.unshift(function(viewValue) {
                if (viewValue == '') {
                    ngModelController.$setValidity('float', true);
                    return viewValue;
                }
                
                if (FLOAT_REGEXP.test(viewValue)) {
                    ngModelController.$setValidity('float', true);
                    return parseFloat(viewValue.replace(',', '.'));
                } 
                
                ngModelController.$setValidity('float', false);
                return undefined;
            });
        }
    };
});

ValidateFloat.spec..js

'use strict';

describe('Validate Float Directive Test', function () {
    var rootScope,
        scope,
        inputElement,
        $body = angular.element('body'),
        simpleHtml = '<input ng-model="modelValue" validate-float>';

    beforeEach(function () {
        module('Library');

        inject(function($injector, $compile) {
            rootScope = $injector.get('$rootScope');
            inputElement = $compile(angular.element(simpleHtml))(rootScope);
        });
    });

    afterEach(function () {
        $body.empty();
    });

    it('Should add a invalid class for a non-float value', function () {
        inputElement.val('XYZ');
        inputElement.trigger('input');
        rootScope.$digest();
        
        // check assigned state classes
        expect(inputElement.hasClass('ng-valid')).toBeFalsy();
        expect(inputElement.hasClass('ng-invalid-float')).toBeTruthy();
        
        // check scopes model value
        expect(rootScope.modelValue).toBeUndefined();
    });
});