General code refactoring/improvements in server, treegen and connection

src/server/mods.h

@@ -22,12 +22,10 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "content/mod_configuration.h"
 #include <memory>
 
-class MetricsBackend;
-class MetricCounter;
 class ServerScripting;
 
 /**
- * Manage server mods
+ * Manages server mods
  *
  * All new calls to this class must be tested in test_servermodmanager.cpp
  */
@@ -36,12 +34,20 @@ class ServerModManager
 	ModConfiguration configuration;
 
 public:
+
 	/**
 	 * Creates a ServerModManager which targets worldpath
 	 * @param worldpath
 	 */
 	ServerModManager(const std::string &worldpath);
-	void loadMods(ServerScripting *script);
+
+	/**
+	 * Creates an empty ServerModManager. For testing purposes.
+	 * Note: definition looks like this so it isn't accidentally used.
+	*/
+	explicit ServerModManager(std::nullptr_t) {};
+
+	void loadMods(ServerScripting &script);
 	const ModSpec *getModSpec(const std::string &modname) const;
 	void getModNames(std::vector<std::string> &modlist) const;