refactor(ngModel): make sure the ngMinlength and ngMaxlength validators use the $validators pipeline

Fixes angular#6304

Author: matsko

src/ng/directive/input.js

@@ -1015,23 +1015,17 @@ function textInputType(scope, element, attr, ctrl, $sniffer, $browser) {
   // min length validator
   if (attr.ngMinlength) {
     var minlength = int(attr.ngMinlength);
-    var minLengthValidator = function(value) {
-      return validate(ctrl, 'minlength', ctrl.$isEmpty(value) || value.length >= minlength, value);
+    ctrl.$validators.minlength = function(value) {
+      return ctrl.$isEmpty(value) || value.length >= minlength;
     };
-
-    ctrl.$parsers.push(minLengthValidator);
-    ctrl.$formatters.push(minLengthValidator);
   }
 
   // max length validator
   if (attr.ngMaxlength) {
     var maxlength = int(attr.ngMaxlength);
-    var maxLengthValidator = function(value) {
-      return validate(ctrl, 'maxlength', ctrl.$isEmpty(value) || value.length <= maxlength, value);
+    ctrl.$validators.maxlength = function(value) {
+      return ctrl.$isEmpty(value) || value.length <= maxlength;
     };
-
-    ctrl.$parsers.push(maxLengthValidator);
-    ctrl.$formatters.push(maxLengthValidator);
   }
 }
 

test/ng/directive/inputSpec.js

@@ -1212,28 +1212,28 @@ describe('input', function() {
 
   describe('minlength', function() {
 
-    it('should invalid shorter than given minlength', function() {
+    it('should invalidate values that are shorter than the given minlength', function() {
       compileInput('<input type="text" ng-model="value" ng-minlength="3" />');
 
       changeInputValueTo('aa');
-      expect(scope.value).toBeUndefined();
+      expect(inputElm).toBeInvalid();
 
       changeInputValueTo('aaa');
-      expect(scope.value).toBe('aaa');
+      expect(inputElm).toBeValid();
     });
   });
 
 
   describe('maxlength', function() {
 
-    it('should invalid shorter than given maxlength', function() {
+    it('should invalidate values that are longer than the given maxlength', function() {
       compileInput('<input type="text" ng-model="value" ng-maxlength="5" />');
 
       changeInputValueTo('aaaaaaaa');
-      expect(scope.value).toBeUndefined();
+      expect(inputElm).toBeInvalid();
 
       changeInputValueTo('aaa');
-      expect(scope.value).toBe('aaa');
+      expect(inputElm).toBeValid();
     });
   });