fix(ngModel): revalidate the model when min/max expression values change for number inputs

As of this fix if the max or min value is changed via scope or by another ngModel
then it will trigger the model containing the min/max attributes to revalidate itself.

Closes angular#2404

Author: matsko

src/ng/directive/input.js

@@ -1129,15 +1129,35 @@ function numberInputType(scope, element, attr, ctrl, $sniffer, $browser) {
   });
 
   if (attr.min) {
+    var minVal;
     ctrl.$validators.min = function(value) {
-      return ctrl.$isEmpty(value) || isUndefined(attr.min) || value >= parseFloat(attr.min);
+      return ctrl.$isEmpty(value) || isUndefined(minVal) || value >= minVal;
     };
+
+    attr.$observe('min', function(val) {
+      if (isDefined(val) && !isNumber(val)) {
+        val = parseFloat(val, 10);
+      }
+      minVal = isNumber(val) && !isNaN(val) ? val : undefined;
+      // TODO(matsko): implement validateLater to reduce number of validations
+      ctrl.$validate();
+    });
   }
 
   if (attr.max) {
+    var maxVal;
     ctrl.$validators.max = function(value) {
-      return ctrl.$isEmpty(value) || isUndefined(attr.max) || value <= parseFloat(attr.max);
+      return ctrl.$isEmpty(value) || isUndefined(maxVal) || value <= maxVal;
     };
+
+    attr.$observe('max', function(val) {
+      if (isDefined(val) && !isNumber(val)) {
+        val = parseFloat(val, 10);
+      }
+      maxVal = isNumber(val) && !isNaN(val) ? val : undefined;
+      // TODO(matsko): implement validateLater to reduce number of validations
+      ctrl.$validate();
+    });
   }
 }
 

test/ng/directive/inputSpec.js

@@ -2894,18 +2894,28 @@ describe('input', function() {
         expect(scope.form.alias.$error.min).toBeFalsy();
       });
 
-      it('should validate even if min value changes on-the-fly', function(done) {
+      it('should validate even if min value changes on-the-fly', function() {
         scope.min = 10;
         compileInput('<input type="number" ng-model="value" name="alias" min="{{min}}" />');
 
-        changeInputValueTo('5');
+        changeInputValueTo('15');
+        expect(inputElm).toBeValid();
+
+        scope.min = 20;
+        scope.$digest();
         expect(inputElm).toBeInvalid();
 
-        scope.min = 0;
-        scope.$digest(function () {
-          expect(inputElm).toBeValid();
-          done();
-        });
+        scope.min = null;
+        scope.$digest();
+        expect(inputElm).toBeValid();
+
+        scope.min = '20';
+        scope.$digest();
+        expect(inputElm).toBeInvalid();
+
+        scope.min = 'abc';
+        scope.$digest();
+        expect(inputElm).toBeValid();
       });
     });
 
@@ -2926,18 +2936,28 @@ describe('input', function() {
         expect(scope.form.alias.$error.max).toBeFalsy();
       });
 
-      it('should validate even if max value changes on-the-fly', function(done) {
+      it('should validate even if max value changes on-the-fly', function() {
         scope.max = 10;
         compileInput('<input type="number" ng-model="value" name="alias" max="{{max}}" />');
 
         changeInputValueTo('5');
         expect(inputElm).toBeValid();
 
         scope.max = 0;
-        scope.$digest(function () {
-          expect(inputElm).toBeInvalid();
-          done();
-        });
+        scope.$digest();
+        expect(inputElm).toBeInvalid();
+
+        scope.max = null;
+        scope.$digest();
+        expect(inputElm).toBeValid();
+
+        scope.max = '4';
+        scope.$digest();
+        expect(inputElm).toBeInvalid();
+
+        scope.max = 'abc';
+        scope.$digest();
+        expect(inputElm).toBeValid();
       });
     });