Fix validateNumericality, nullCheck & add tests

validateNumericality didn't test if attributes value is a number
only if it's type is number.
Further nullCheck had a wrong testing order. It first checked if
value is null, later if blank. Also null check only used two equals,
not three. We don't use blank() anymore, testing if variable is
undefined should be fine too.
Added tests covering validateNumericality.

lib/validations.js

@@ -287,7 +287,7 @@ function validateLength(attr, conf, err, options) {
 function validateNumericality(attr, conf, err, options) {
   if (nullCheck.call(this, attr, conf, err)) return;
 
-  if (typeof this[attr] !== 'number') {
+  if (typeof this[attr] !== 'number' || isNaN(this[attr])) {
     return err('number');
   }
   if (conf.int && this[attr] !== Math.round(this[attr])) {
@@ -633,16 +633,26 @@ var defaultMessages = {
   uniqueness: 'is not unique',
 };
 
+/**
+ * Checks if attribute is undefined or null. Calls err function with 'blank' or 'null'.
+ * See defaultMessages. You can affect this behaviour with conf.allowBlank and conf.allowNull.
+ * @param {String} attr Property name of attribute
+ * @param {Object} conf conf object for validator
+ * @param {Function} err
+ * @return {Boolean} returns true if attribute is null or blank
+ */
 function nullCheck(attr, conf, err) {
-  if (this[attr] == null) {
-    if (!conf.allowNull) {
-      err('null');
+  // First determine if attribute is defined
+  if (typeof this[attr] === 'undefined') {
+    if (!conf.allowBlank) {
+      err('blank');
     }
     return true;
   } else {
-    if (blank(this[attr])) {
-      if (!conf.allowBlank) {
-        err('blank');
+    // Now check if attribute is null
+    if (this[attr] === null) {
+      if (!conf.allowNull) {
+        err('null');
       }
       return true;
     }

test/validations.test.js

@@ -558,7 +558,65 @@ describe('validations', function() {
   });
 
   describe('numericality', function() {
-    it('should validate numericality');
+    it('passes when given numeric values', function() {
+      User.validatesNumericalityOf('age');
+      var user = new User({age: 10});
+      user.isValid().should.be.true();
+    });
+
+    it('fails when given non-numeric values', function() {
+      User.validatesNumericalityOf('age');
+      var user = new User({age: 'notanumber'});
+      user.isValid().should.be.false();
+      user.errors.should.eql({age: ['is not a number']});
+    });
+
+    it('fails when given undefined values', function() {
+      User.validatesNumericalityOf('age');
+      var u = new User({});
+      u.isValid().should.be.false();
+      u.errors.should.eql({age: ['is blank']});
+    });
+
+    it('skips undefined values when allowBlank option is true', function() {
+      User.validatesNumericalityOf('age', {allowBlank: true});
+      var user = new User({});
+      user.isValid().should.be.true();
+    });
+
+    it('fails when given non-numeric values when allowBlank option is true', function() {
+      User.validatesNumericalityOf('age', {allowBlank: true});
+      var user = new User({age: 'test'});
+      user.isValid().should.be.false();
+      user.errors.should.eql({age: ['is not a number']});
+
+    });
+
+    it('fails when given null values', function() {
+      User.validatesNumericalityOf('age');
+      var user = new User({age: null});
+      user.isValid().should.be.false();
+      user.errors.should.eql({age: ['is null']});
+    });
+
+    it('passes when given null values when allowNull option is true', function() {
+      User.validatesNumericalityOf('age', {allowNull: true});
+      var user = new User({age: null});
+      user.isValid().should.be.true();
+    });
+
+    it('passes when given float values', function() {
+      User.validatesNumericalityOf('age');
+      var user = new User({age: 13.37});
+      user.isValid().should.be.true();
+    });
+
+    it('fails when given non-integer values when int option is true', function() {
+      User.validatesNumericalityOf('age', {int: true});
+      var user = new User({age: 13.37});
+      user.isValid().should.be.false();
+      user.errors.should.eql({age: ['is not an integer']});
+    });
   });
 
   describe('inclusion', function() {