Method json() to parse JSON strings

- Parse a JSON string into array
- Test

src/Expectation.php

@@ -60,6 +60,17 @@ final class Expectation
         return new self($value);
     }
 
+    /**
+     * Parses Json String to Array.
+     */
+    public function json(): Expectation
+    {
+        Assert::assertIsString($this->value);
+        Assert::assertJson($this->value);
+
+        return new self(json_decode($this->value, true));
+    }
+
     /**
      * Dump the expectation value and end the script.
      *