Add test

Author: sebastiaanluca

tests/BooleanAttributeTest.php

@@ -234,6 +234,18 @@ public function it can disable a boolean attribute from an integer(): vo
         $this->assertNull($model->accepted_terms_at);
     }
 
+    /**
+     * @test
+     */
+    public function it can disable a boolean attribute from an empty string(): void
+    {
+        $model = new TestModel;
+
+        $model->has_accepted_terms = '';
+
+        $this->assertNull($model->accepted_terms_at);
+    }
+
     /**
      * @test
      */