fix(input): create max and/or min validator regardless of initial value

Also adds corresponding tests for ngMin / ngMax.

Fixes #10307
Closes #10327

Author: tobyee

src/ng/directive/input.js

@@ -1250,7 +1250,7 @@ function numberInputType(scope, element, attr, ctrl, $sniffer, $browser) {
     return value;
   });
 
-  if (attr.min || attr.ngMin) {
+  if (isDefined(attr.min) || attr.ngMin) {
     var minVal;
     ctrl.$validators.min = function(value) {
       return ctrl.$isEmpty(value) || isUndefined(minVal) || value >= minVal;
@@ -1266,7 +1266,7 @@ function numberInputType(scope, element, attr, ctrl, $sniffer, $browser) {
     });
   }
 
-  if (attr.max || attr.ngMax) {
+  if (isDefined(attr.max) || attr.ngMax) {
     var maxVal;
     ctrl.$validators.max = function(value) {
       return ctrl.$isEmpty(value) || isUndefined(maxVal) || value <= maxVal;

test/ng/directive/inputSpec.js

@@ -1869,12 +1869,17 @@ describe('input', function() {
       });
 
       it('should validate even if min value changes on-the-fly', function() {
-        $rootScope.min = 10;
+        $rootScope.min = undefined;
         var inputElm = helper.compileInput('<input type="number" ng-model="value" name="alias" min="{{min}}" />');
+        expect(inputElm).toBeValid();
 
         helper.changeInputValueTo('15');
         expect(inputElm).toBeValid();
 
+        $rootScope.min = 10;
+        $rootScope.$digest();
+        expect(inputElm).toBeValid();
+
         $rootScope.min = 20;
         $rootScope.$digest();
         expect(inputElm).toBeInvalid();
@@ -1910,12 +1915,17 @@ describe('input', function() {
       });
 
       it('should validate even if the ngMin value changes on-the-fly', function() {
-        $rootScope.min = 10;
+        $rootScope.min = undefined;
         var inputElm = helper.compileInput('<input type="number" ng-model="value" name="alias" ng-min="min" />');
+        expect(inputElm).toBeValid();
 
         helper.changeInputValueTo('15');
         expect(inputElm).toBeValid();
 
+        $rootScope.min = 10;
+        $rootScope.$digest();
+        expect(inputElm).toBeValid();
+
         $rootScope.min = 20;
         $rootScope.$digest();
         expect(inputElm).toBeInvalid();
@@ -1952,12 +1962,17 @@ describe('input', function() {
       });
 
       it('should validate even if max value changes on-the-fly', function() {
-        $rootScope.max = 10;
+        $rootScope.max = undefined;
         var inputElm = helper.compileInput('<input type="number" ng-model="value" name="alias" max="{{max}}" />');
+        expect(inputElm).toBeValid();
 
         helper.changeInputValueTo('5');
         expect(inputElm).toBeValid();
 
+        $rootScope.max = 10;
+        $rootScope.$digest();
+        expect(inputElm).toBeValid();
+
         $rootScope.max = 0;
         $rootScope.$digest();
         expect(inputElm).toBeInvalid();
@@ -1993,12 +2008,17 @@ describe('input', function() {
       });
 
       it('should validate even if the ngMax value changes on-the-fly', function() {
-        $rootScope.max = 10;
+        $rootScope.max = undefined;
         var inputElm = helper.compileInput('<input type="number" ng-model="value" name="alias" ng-max="max" />');
+        expect(inputElm).toBeValid();
 
         helper.changeInputValueTo('5');
         expect(inputElm).toBeValid();
 
+        $rootScope.max = 10;
+        $rootScope.$digest();
+        expect(inputElm).toBeValid();
+
         $rootScope.max = 0;
         $rootScope.$digest();
         expect(inputElm).toBeInvalid();