feat: replace integer check with Number.isInteger (#405)

BREAKING CHANGE: use Number.isInteger. This works correctly for large numbers.

Related to #147

src/number.js

@@ -5,17 +5,15 @@ import isAbsent from './util/isAbsent';
 
 let isNaN = value => value != +value;
 
-let isInteger = val => isAbsent(val) || val === (val | 0);
-
 export default function NumberSchema() {
   if (!(this instanceof NumberSchema)) return new NumberSchema();
 
   MixedSchema.call(this, { type: 'number' });
 
   this.withMutation(() => {
     this.transform(function(value) {
-      let parsed = value
-      
+      let parsed = value;
+
       if (typeof parsed === 'string') {
         parsed = parsed.replace(/\s/g, '');
         if (parsed === '') return NaN;
@@ -94,7 +92,11 @@ inherits(NumberSchema, MixedSchema, {
   },
 
   integer(message = locale.integer) {
-    return this.test({ name: 'integer', message, test: isInteger });
+    return this.test({
+      name: 'integer',
+      message,
+      test: val => isAbsent(val) || Number.isInteger(val),
+    });
   },
 
   truncate() {

test/number.js

@@ -203,8 +203,8 @@ describe('Number types', function() {
     var schema = number().integer();
 
     TestHelpers.validateAll(schema, {
-      valid: [4, -5222],
-      invalid: [10.53, 0.1 * 0.2, -34512535.626, 3.12312e51, new Date()],
+      valid: [4, -5222, 3.12312e51],
+      invalid: [10.53, 0.1 * 0.2, -34512535.626, new Date()],
     });
 
     it('should return default message', () => {