First unit tests, misc fixes

src/Configuration.php

@@ -108,5 +108,19 @@ class Configuration
         return $this;
     }
 
+    public function getOverwriteMessageIds(): bool
+    {
+        return $this->config['publish.overwrite_ids']??true;
+    }
+
+    public function getRejectDuplicateMessages(): bool
+    {
+        return $this->config['publish.reject_duplicates']??true;
+    }
+
+    public function getDuplicateIdHistorySize(): int
+    {
+        return 50;
+    }
 }