diff --git a/tests/TestCase.php b/tests/TestCase.php
index 397c713b..689922b4 100755
--- a/tests/TestCase.php
+++ b/tests/TestCase.php
@@ -126,6 +126,12 @@ class TestCase extends Illuminate\Foundation\Testing\TestCase
             if (is_subclass_of($value, App\Interfaces\Unit::class)) {
                 $data[$key] = $value->__toString();
             }
+
+            if($value instanceof DateTime) {
+                $data[$key] = $value->format(DATE_ATOM);
+            } elseif ($value instanceof Carbon) {
+                $data[$key] = $value->toIso8601ZuluString();
+            }
         }
 
         return $data;