Add JsonDriver validation

Author: sebastiandedeyne

src/Drivers/JsonDriver.php

@@ -4,6 +4,7 @@
 
 use PHPUnit\Framework\Assert;
 use Spatie\Snapshots\Driver;
+use Spatie\Snapshots\Exceptions\CantBeSerialized;
 
 class JsonDriver implements Driver
 {
@@ -13,6 +14,10 @@ public function serialize($data): string
             $data = json_decode($data, true);
         }
 
+        if (! is_array($data)) {
+            throw new CantBeSerialized('Only strings can be serialized to json');
+        }
+
         return json_encode($data, JSON_PRETTY_PRINT).PHP_EOL;
     }
 

tests/Unit/Drivers/JsonDriverTest.php

@@ -4,6 +4,8 @@
 
 use PHPUnit\Framework\TestCase;
 use Spatie\Snapshots\Drivers\JsonDriver;
+use Spatie\Snapshots\Exceptions\CantBeSerialized;
+use stdClass;
 
 class JsonDriverTest extends TestCase
 {
@@ -84,4 +86,14 @@ public function it_can_serialize_a_json_array_to_pretty_json()
 
         $this->assertEquals($expected, $driver->serialize(['foo', 'bar', 'baz']));
     }
+
+    /** @test */
+    public function it_can_only_serialize_strings_and_arrays()
+    {
+        $this->expectException(CantBeSerialized::class);
+
+        $driver = new JsonDriver();
+
+        $driver->serialize(new stdClass);
+    }
 }