Convert empty string access token to null

Author: loevgaard

src/Pixel/Pixel.php

@@ -21,7 +21,7 @@ final class Pixel
     public function __construct(string $id, string $accessToken = null)
     {
         $this->id = $id;
-        $this->accessToken = $accessToken;
+        $this->accessToken = '' === $accessToken ? null : $accessToken;
     }
 
     public function __toString(): string

tests/Pixel/PixelTest.php

@@ -28,4 +28,13 @@ public function it_is_stringable(): void
         $pixel = new Pixel('id');
         self::assertSame('id', (string) $pixel);
     }
+
+    /**
+     * @test
+     */
+    public function it_converts_empty_string_access_token_to_null(): void
+    {
+        $pixel = new Pixel('id', '');
+        self::assertNull($pixel->accessToken);
+    }
 }