Fix: isJSON now returns false for empty strings

README.md

@@ -527,7 +527,9 @@ s('A102F')->isHexadecimal(); // true
 
 ##### isJson()
 
-Returns true if the string is JSON, false otherwise.
+Returns true if the string is JSON, false otherwise. Unlike json_decode
+in PHP 5.x, this method is consistent with PHP 7 and other JSON parsers,
+in that an empty string is not considered valid JSON.
 
 ```php
 s('{"foo":"bar"}')->isJson(); // true

src/Stringy.php

@@ -589,12 +589,18 @@ class Stringy implements \Countable, \IteratorAggregate, \ArrayAccess
     }
 
     /**
-     * Returns true if the string is JSON, false otherwise.
+     * Returns true if the string is JSON, false otherwise. Unlike json_decode
+     * in PHP 5.x, this method is consistent with PHP 7 and other JSON parsers,
+     * in that an empty string is not considered valid JSON.
      *
      * @return bool Whether or not $str is JSON
      */
     public function isJson()
     {
+        if (!$this->length()) {
+            return false;
+        }
+
         json_decode($this->str);
 
         return (json_last_error() === JSON_ERROR_NONE);

tests/StringyTest.php

@@ -2066,7 +2066,13 @@ class StringyTestCase extends PHPUnit_Framework_TestCase
     public function isJsonProvider()
     {
         return array(
-            array(true, ''),
+            array(false, ''),
+            array(false, '  '),
+            array(true, 'null'),
+            array(true, 'true'),
+            array(true, 'false'),
+            array(true, '[]'),
+            array(true, '{}'),
             array(true, '123'),
             array(true, '{"foo": "bar"}'),
             array(false, '{"foo":"bar",}'),